Potential Purine Antagonists. VI. Synthesis of 1-Alkyl- and 1-Aryl-4-substituted Pyrazolo[3,4-d]Pyrimidines

[COXTRIBVTIOX FROM THE DEPARTMENT CHEMISTRY, NEW iMEXIC0 HIGHLANDS OF UNIVERSITY] Potential Purine Antagonists. VI. Synthesis of I-Alkyl- and I-Aryl-4-substituted PyrazoI0[3,4-d]pyrimidines~~~ C. C. CIIENG ROLAND K. ROBINS AND Received M a y 21, 1956 Various monosubstituted hydrazines have been reacted with ethoxymethylenemalononitrile to yield the corresponding l-substituted-5-amino-4-cyanopyrazolcs (IV). Treatment of IV with concentrated sulfuric acid gave the corresponding l-substituted-5-aminopyr~zole-4carbosmides (XVI). The structure of 5-amino-1-phenylpyrazole-4-carbosamide was established by an unambiguous synthesis. The preparation of 1-alkyl- and l-argl-l-aminoayrazolo[3,4-d]pyriniidines been accomplished by treating the correhas sponding 1-alkyl(or aryl)-5-amino-4-cyanopyrazole (IV) with boiling formamide. Heating 1-alkyl( or aryl)-5-amino-4pyrazolecarboxamide (XVI) with formamide in a similar manner gave the corresponding 1-alkyl( or aryl)-4-hydrosypyrazolo[3,4d]pyrimidine (XVII). Phosphorus osychloride and XVII yielded the 1-alkyl- or l-aryl-4-chloropyrazolo[3,4-d] pyrimidine (XVIII) which then was utilized for the synthesis of various additional 4-substituted pyrazolo[3,4d] pyrimidines by nucleophilic displacement of the chlorine atom. I n accord with a program for the synthesis of various puriiie antagonists, a number of compounds containing the pyrazolo [3,4-d]pyrimidine nucleus hare recently been prepared in this laboratory.3 The inhibition of the growth of Adenocarcinoma 755 and Leukemia 51'78 in mice by 4-aminopyrazolo [3,4-d]pyrimidine and 1-methyl-4-aminopyrazolo [3,4-d]pyrimidine4as well as the inhibition of cellular growth by 4-aminopyrazolo [3,4-d]pyrimidine in rertnin tissue culture studies5has prompted XI'., R, "C. Yield (%) of U. V. Absorption Purified xmsx. (mp) Product pH = 1 pH = 11 222-223 158-160 140 187-167.5 168-170 124 224-225 86.4 83.5 80 0 77.5 40.0 61.0 81.0 238 225 224 230 233 158- 159 84.0 Since in the early synthetic studies of this series 1-met hyl-4-aminopyrazolo [3,4-d]pyrimidiiie was prepared and found to possess anti-tumor activity,4 a complete investigation of the preparation of 1alkyl- and 1-aryl-4-subst itut ed pyrazolo [3,4-d ]pyrimidines was undertaken. It was discovered that when a mono-substituted hydrazine (I), either aliphatic or aromatic, was reacted with ethoxyniethylenemalononitrile (11) in boiling alcoholic solution, the corresponding l-al- Recrystallization Solvents Water Ethanol Water Ethanol Ethanol Ethanol Ethanol 226 285 ' 235 235 235 234 238 285 Analyses Found N C H Calc'd C H 49.2 4 92 45.9 49.2 4.62 26.8 65.1 4.40 30.4 65 2 4 35 25.7 21 3 25 7 30 c, 46.0 20.8 30.8 25 7 21.4 25.7 30 1 28.3 28 2 Ethanol and water further investigation of derivatives containing this ring system. In particular, it seemed desirable to synthesize various substituted 4-aminopyrazolo [3,4dlpyrimidines. N kyl- or l-aryl-5-amino-4-cyanopyrazole (IV) was formed in good yield. The various l-substituted-5amino-4-cyanopyrazoles synthesized in this manner are listed in Table I. ( 1 ) This investigation was supported by research grant C-2105(C) from the National Cancer Institute of the National Institutes of Health, Public Health Service. (2) Presented in part before the Division of Organic Chemistry, 129th Meeting of the American Chemical Society, Dallas, Texas, ,4pril, 1956. ( 3 ) Robins, J. Am. Chem. SOC., 784 (1956). 78, (4) Skipper, Robins, and Thompson, Proc. Sac. Ezptl. Biol. Med., 89, 594 (1955). (5) HSU,Flobins, and Cheng, Science, 123, 848 (1956). 1240 RiNHNHz + ,G N C CzH@CH=C, I I1 r \ 111 C-N CENJ -- - Ri l H2N --?/N-N I I1 NI C IV The question of the condensation of a mono-substituted hydrazine (I) and ethoxymethylenemalononitrile (11) to form the alternative structure, 1alkyl(aryl)-3-amino-4-cyanopyrazole(VI), although rather unlikely, cannot entirely be eliminated sincc the reaction could conceivably proceed as follows : 2 " I + RINH / X I CH&O CEN A CiH5OCH=C, I 4-ethylcarboxylate (XII), was prepared by Michaelis and Remy' by the reaction of ethoxymethylenemalonic ester (VIII) n-ith P-acetglphenylhydrazine (XI) in phosphorus oxychloride. The syntheses of X and XI1 were repeated in this laboratory. The ultraviolet absorption spectra CEN HO HsCzOOC - XI1 VI V Several investigations were carried out in order to support the assigned structure of I-alkyl(ary1)5-amino-4-cyanopyrazole (IV) . Claisen and Haase6 prepared 5-hydroxy-1-phenylpyrazole-4-ethylcarboxylate (X) by the reaction of phenylhydrazine (VII) and ethoxymethylenemalonic ester (T'III) in diethyl ether: of X and XI1 were found to differ considerably. At pH 1, X had Amax, 219 mp and XI1 had A,,. 275 nip. At p H 11,X had A,, 237 nip and XI1 had A,,. 306 mp. 5-Amino-4-cyano-1-phenylpyrazole (IV, R1 = C6H5) was converted by concentrated sulfuric acid to 5-amino-1-phenylpyrazole-4-carboxamide (XVI, R1 = CtH5). This latter compound was found to @, / COOCrHj of 22.5 mp a t pH 1and A,., of 240 mp a t possess A,,. C~H~OCH=C; pH 11. This information suggests that the structure COOCzHs assigned to 5-amino-1-phenylpyrazole-4-carboxVI1 VI11 amide is correct since the ultraviolet absorption spectra resemble that of X rather closely. / COOCiHs I The structure of 5-aniino-l-phenylpyrazole-4~NHNHCH=C< + HO --f"'f;' carboxamide (XV) was definitely established in the COOCzHs HsCzOOC following manner. 5-Hydroxy-l-phenylpyrazole-4v IX ethylcarboxylate (X) was treated lyith phosphorus The intermediate I X was isolated, m.p. 112", oxychloride and phosphorus pentachloride to give and cyclization of the pyrazole ring required heat- 5 - chloro - 1 - phenylpyrazole - 4 - ethylcarboxylate, ing IX to 170-175". The structure of 5-hydroxy-l- which was treated with alcoholic ammonia in a phenylpyrazole-4-ethylcarboxylate was definitely bomb a t 170" to give 5-amino-I-phenylpyrazoleestablished by Claisen and Haase by hydrolysis of 4-carboxamide (XV). This compound v a s shown to = X followed by decarboxylation to give the known be identical to XVI (R, CsHs),synthesized from 5-amino-4-cyano-1-phenylpyrazole (ITr, R, = Ca5-h ydroxy-1-phenylp yrazole. The other isomer, 3-hydroxy-1-phenylpyrazole- Hb). LJNHNH, + fi Y ~ L ' TABLE I1 M.P., "C. Ri Yield (yo) U. V. Absorption of Purified ~ r n a x (m/4) . Product pH = I pH = 11 CHP 237-239 95 CHZCHZOH CBH~ p-cl-C~H4 p-CH3-Ce,H' 273-275 172-1 73 204-208 173-175 98 84 86 80 223 280 262 225 230 223 259 Recrystallization Solvents C:tlc'd C I - Analyses Found I N C H 281 Water 42 9 5 7 2 40 0 43 3 5 GO 40.0 259 240 239 23G Ethanol Ethanol and water Ethanol and water Water 20.9 21 0 59.4 4.95 27.7 50 5 4.87 28.1 23.6 23 3 25 9 25 8 ~~~~ (6) Clnisen and Haase, Ber., 28, 36 (1895). N (7) Michaelis and Remy, Ber., 40, 1020 (1907). 1212 CHENG AXD KOBINS m MQ w-l m H * 0 I. - - - M m k CI m 3 NOVEMBER 1956 POTENTI.4L PURINE SNT.4GONISTS. n 3 w Am 4 w 2 8 0 0 8 cc n A A 5 7 H R 2 C q 0" 7. Y x" s d VI 1243 124 1 I CIIENG ANI) TlOllINS VOI,. I k t ; : - x x 21 NOVEMBER 1956 POTENTIAL PURINE ANTAGONISTS. 1245 VI 00 9 t , 9 r" r3 1 0 l i 0 3 x s " 3 c ( ? E s ; ' w, u u" u iz E u u" Y L? I R 5 % E G d c Y b 2 1246 VOL. CHENG AND ROBINS Y ? e N 8 d: d . n? m L ? CJ m 0 F? p1 F7 * -44 4 F3 -4 4 4 - 4 4 b M 3 x x x z x x x x" x w u w M w x @ u c @ 21 NOVEMBER 1966 Y m cy POTENTIAL PURINE ANTAGONISTS. 09 cy cy Y" 09 3 c y 0 i 3 c y m 3 c m y 1247 VI Q l POC1, PCL Alc. F i NH, u u H.N+? H2N-C 0 i f - ll xv This established the structure of 5-amino-4-cyano-1-phenylpyrazole. Since the ultraviolet absorption spectra for 5-amino-1-methylpyrazole-4-carboxamide and 5-amino-1-phenylpyrazole-&carboxamide are quite similar, it would follow that the structure assigned to 5-amino-4-cyano-1-methylpyrazole (IV, R, = CH3) was also correct. It was found that treatment of the 1-alkyl(ary1)5-amino-4-pyrazoles (IV) with cold concentrated sulfuric acid gave the corresponding 1-alkyl(ary1)5-amino-4-pyrazole carboxaniide (XVI) ; (See Table 11.) This reaction proceeds in a manner similar to the preparation of 3-aminopyrazole-4-carboxamide f roni 3-amino-4-cyanopyrazole. 1-illkyl (Aryl)-5amino-4-pyrazole carboxamide then was converted to the corresponding l-alkyl(aryl)-4-hydroxypyrazolo [3,4-d]pyrimidine (XVII), (Table 111), with boiling formamide. The 1-alkyl- or 1-aryl-4-chloropyrazolo [3,4-d]pyriniidiiies (XVIII) listed in Table I11 were obtained by refluxing the corresponding 4-hydroxy derivatives (XVII) with phosphorus oxychloride. Chlorination proceeded smoothly, and it was found that the addition of dimethylaniline to the reaction misRi I ljl I 7' Ri 1248 C H E S G A N D ROBINS VOL. 21 ture was unnecessary. This observation is interR 1 esting since the chlorination of 4-hydroxypyrazolo[3,4-d]pyriniidine requires both dimethylaiiiline and phosphorus oxy~hloride.~ The preparation of the various l-alkyl(aryl)-4OH 0 aininopyrazolo [3,4-d]pyrimidines (XIX) listed in XVII XXIII Table I T - vias acconiplished by two routes. The treatment of l-alkyl(aryl)-5-aniino-4-cyaiiopyrazole (IY)with boiling formaniide offered the most direct niethod oi synthesis. It is to be noted that thc treatment of nii o-substituted aminonitrile with forniamide to rlose the pyrimidine ring was first] applied successfully to the synthesis of 4-amiiiopyrazolo [3,4-d]pyrimidi1ie.~ This method has since been utilized effectively in the synthesis of 4-aminopyriniido i~,j-l,]cluiiioliiie.s To check 011 the structures formed b y this ring closure, several 4aminoderivatives were also prepared from the corresponding 4 - chloropyrazolo [3,4 - dlpyrimidines (XT-111). n'umerous K-substituted amino derivatives (XXJ?) were prepared by the reaction of XVIII RI R i with various primary and secondary amines in al1 t p T i p coholic or benzene solution refluxed on the steam bath. N , N , The 1-alkyl (aryl)-4-mere apt opyrazolo [3,4-d]pyrimidines (XX) were synthesized from either the Ra-N-Ra 0-R, correspondiiig 4-hydroxy derivative (XT'II) with xxv XXVI XXVII phosphorus pentasulfide in tetralin or pyridine, or REACTION SCHEhIE by treatment of the corresponding 4-chloro compounds (ST7111) with thiourea in boiling ethanol. Alkylation of XX with alkyl iodides resulted in 1,5-dimethylpyrazolo[3,4-d]pyriniidone-i (XXIII, R1, Rz = CH,). Treatment of this compound with the 4-alkylmercapto derivatives (XXI). Several of the 4-alkylmercapto derivatives were phosphorus pentasulfide in tetralin gave a cornalso obtained from the l-alkyl(aryl)-4-chloropy- pound which is apparently 1,5-dimethylpyrazolorazolo r3,4-d]pyrimidine (XVIII) and the appropri- /3,4-d]pyrimidine-4-thione (XXIV, R,, R2 = CH,). A similar thiation has previously been reate alkyl mercaptan in basic media. 4-(p-Chlorophenylmercapto)-l -niethylpyrazolo- ported by Elion and Hitchings.lo l-Methylpyrazolo[3,4-d]pyrimidine(XXV, R, = [3,&d]pyrimidine (XXI, R2 = p-ClC,&) was madc by the reaction of p-chlorothiophenol and 4-chloro- CH,) was prepared by catalytic dehalogenation of 1-met hylpyrazolo [3 , ~ ] pyrimidine. However, it 1 - methyl - 4 - chloropyrazolo[3,4 - dlpyrimidine was fourid that this reaction proceeded only in an- (XVIII, R, = CH,) using a palladium on charcoal hydrous benzene. The ultraviolet absorption spec- catalyst, This procedure has been used successfully tra of this conipound in ethanol is similar t o that of for the preparation of purine.g Inspection of the ultraviolet absorption spectra the corresponding 4-niethylmercapto derivative ; however, in aqueous solution (pH 1 and pH 11) the of XT'II, (R, = CH3), XXIII, (RI, R, = CHZ), spectra is identical to that of 4-hydroxy-1-methyl- and XXVII, (Rl, R, = CH?) in methanol (see Figpyrazolo [3,4-d]pyrimidine, indicating the rapid Iiy- ure 1) reveals that in neutral solution the structure drolysis of the p-chlorophenylniercapto group in of XVII, (R,= CH,), is probably best represented as 1-methyl - 5 - €1 - pyrazolo [3,4- dlpyrimidone - 4 aqueous solution. Various 4-alkoxy derivatives (&XXVII)were ob- (XXII). Similarly, the ultraviolet absorption tained from the appropriate l-alkyl(aryl)-4-chloro'743 pyrazolo [3,4-d]pyrimidine (XVIII) and the correI sponding sodium aikoside. AIethylation of 1N N,N methyl - - - hydrosypyrazolo[3,4 - dlpyrimidine 1 ) 1 (XT'II, l L == CH?) resulted in the preparation of I c p H-$p ( 8 ) Taylor :tnd Knlenda, J . A m . Chem. Soc., 78, 5108 (19.56). (9) Berrdich, Russell, and Fox, J. Am. Chenz. Soc., 76, GO73 (1954). 0 XXII (10) Elion and Hitchings, J . A m . Chem. SOC., 69, 2138 (1947). NOVEMBER 1956 POTENTIALPURINE ANTAGONISTS. 1249 VI 1.0 A ” , u1 S Q) a 0 I ) .4 a 0 0.I 0. I ai o a40 260 280 300 320 A (my) FIG. 1. ULTRAVIOLET ABSORPTIOK SPECTRA CERTAIN~-METHYLPYRAZOLO] P Y R I ~ I I D I S E S , OF [~,~-~ concentration 10 mg./liter, run in methanol. -0-0-0- 1-Methyl-4-methoxypyrazolo [3,4-d] pyrimidine (XXVII, R1, R, = CHI); -A-A-A1-Methy1-41,s-Dimethylpyrazolo [3,4-d]pyrimidone-4 (XXIII hydroxypyrazolo [3,4-d] pyrimidine (XVII, R1 = CH,); -X-X-XRi, R, C&). curves of XX, (R,= CH,), XXIV, (R1, R = z CHs), and XXI, (R1, z = CHI) (see Figure 2) R indicate that XX, (R1= CH,) in neutral solution is predominantly 1-methyl-5-H-pyrazolo[3,4-d]pyrimidine-4-thione (XXJ’III). accomplished by still another route. 4-Mercaptopyrazolo [3,4-d]pyrimidine3 treated with an excess of methyl iodide in the presence of base gave a good yield of XXI, (Rl, R2 = CHI). Similarly, methylation of 4-hydroxypyrazolo [3,4-d]pyrimidine3 with methyl iodide yielded 1,5-dimethylpyrazolo[3,4CHs dlpyrimidone-4 (XXIII, R1, Ra = CH,). 4-DiI methylaminopyrazolo [3,1-dlpyrimidine3 methyl and N N.N iodide gave 1-methyl-4dimethylaminopyrazolo [3,4dlpyrimidine (XXVI, R1, R = CH,). In these R3, q methylation studies in each instance none of the S theoretically possible “2-methyl” isomers were obFXVIII tained. The structure of the 1-methyl derivative in The synthesis of 1-methyl-4-methylmercaptopyr-each case had been previously determined by inazolo[3,4-d]pyrimidine (XXT, R1, = CH,) was dependent synthesis. .-;p 1250 CHENG AXD ROBINS 220 240 260 VOI,. 300 x 340 21 360 (my) FIG. 2. ULTRAVIOLET ABSORPTIOX SPECTRA CERTAIN1-METHYLPYRAZOLO OF [3,4-d]PYRIJIIDINES, concentration 10 mg./liter, run in methanol. -0-0-0- 1-Methyl-4-methylmercaptopyrazolo[3,4-d]pyrimidine (XXI, R1, Ra = CHI); -A-A-A1-Methyl4-mercaptopyrazolo [3,4-d]pyrimidine (XX, R1 = CHa); -X- X- X- 1,5-Dimethylpyrazolo [3,4-d]pyrimidine-4-thione (XXIV, Ri, R, = CH,). The general method of synthesis of pyrazolo [3,4dlpyrimidines from a pyrazole intermediate3 has nom been further extended to include the synthesis of various 3-methylpyrazolor3,4-d]pyrimidines. The synthesis of methylethoxymethylenemalononitrile (XXIX) was accomplished from triethyl orthoacetate, malononitrile, and acetic anhydride. XXIX and hydrazine gave 3-amino-4-cyano-5methylpyrazole (XXX) in a manner similar to the H f p H N I NHa 4-Aminopyrazolo [3,4-d]pyrimidine I NHz XXXI Methylethoxymethylenemalononitrile (XXIX) mas also reacted with several substituted hydrazines to give the corresponding l-alkyl(aryl)-3methyl-5-amino-4-cyanopyrazoles (XXXII). HyCHa NEC, 1 drolysis of XXXII with concentrated sulfuric acid H gave l-alkyl(aryl)-3-methyl-5-aminopyrazole-4-car'C=C-OC2H6 + H2NNHz-+ H2N*N-N / boxamide (XXXIII). Compounds XXXIV and NEC N rc CH, X X X V were synthesized in the usual manner by XXIX xxx heating XXXII and XXXIII respectively with synthesis of 3-amino-4-cyanopyrazole. Treatment formamide. With regard to the biological interest in this of XXX with boiling formamide yielded 3-methyl4-aminopyrazolo [3,4-d]pyrimidine (XXXI). This group of compounds, the anti-tumor activity of 1compound is of interest due to its structural rela- methyl-4-aminopyrazolo[3,4-d]pyrimidine (XIX, tionship to 4-aminopyrazolo[3,4-d]pyrimidine3 R1 = CH,) has already appeared in a preliminary which has been shown to possess antitumor activ- report.4 it,y.4,5 1-Methyl-4 - methylaminopyrazolo [3,4- dlpyrimi- I NOVEMBER 1956 POTEKTIAL I'UlZINE ANTBGONISTS. VI 1251 addition caused a smooth boiling of the solution, and a yellow, needle-like substance gradually precipitated from the hot solution. The reaction mixture was boiled gently for H2N 15 minutes after the final addition of ethoxymethyleneHZN-C CHa malononitrile. The solution then was cooled and the product II was filtered and washed with a small amount of ether. The O XXXIII yield was 125 g. (77.5y0), m.p. 159-163'. Light-yellow crvstals. m.D. 167-167.5', were obtained after recrystallizaH - L I , tion froin et6anol. Anal. Calc'd for ClOH7ClN4: N, 25.7. Found: N, 25.7. Preparation of 6-amino-~-cyano-l-~-hydroxyethylpyrazole RI R L (IV, R1 = CH2CH20H).T o 42 g. of 70% B-hydroxyethylI hydrazine in 100 ml. of ethanol was added carefully 50 g. of ethoxymethylenemalononitrile. The mixture was then boiled gently on a steam-bath for 30 minutes. A white precipitate gradually appeared from the hot solution. The reaction mixture was cooled and filtered and the solid washed OH 2 " with ether. White crystals, m.p. 158-160", were obtained XXXIV after recrystallization of the crude product from ethanol. Thc yield of purified material was 54 g. (83.570). dine (XXVI, R,, = CHa,R3 = H) has recently" Rq Anal. Calc'd for CeHsN10: N, 26.8. Found: N, 26.8. been found to exhibit a similar activity against The other l-aryl-5-amino-4-cyanopyrazoles listed in Table Adenocarcinoma 755 and Leukemia 5178. Further I were prepared by essentially the same procedure. Preparation of 6-amino-l-methylpyrazoEe-4-carboxamide biological testing is now in progress. A complete re(XVI, R1 = CHI). To 100 ml. of concentrated sulfuric acid port will appear elsewhere. cooled in an ice-bath was gradually added, with stirring, Acknowledgment. The authors wish to express 40 g. of powdered 5-amino-4cyano-I-methylpyrazole (IV, t'heir thanks to Merien Lamon Robins and Kwei- R1 = CH8). The inside temperature was kept between 1520". The addition n-as accomplished over a period of 2 Chao Chao for their valuable technical assistance. hours, and the solution then was stirred a t room temperature for an additional 30 minutes and then was poured, with stirring, onto 500 g. of crushed ice. The solution was EXPERIMEXTAL'~ adjusted to pH 8 with concentrated ammonium hydroxidc. Preparation oj"5-amino-4-cyano-l-methylpyrazole (IV, It1 = Enough ice was added during the neutralization in order to CHI). To 700 mi. of absolute ethanol and 70 g. of 98% maintain a temperature below 50'. The final volume was methylhydrazine was carefully added, a little a t a time, approximately 1200 ml. The solution was cooled overnight The 121 g. of eth~xymethylenemalononitrile.~~ addition was and finally filtered to yield 30 g. of colorless crystals, m.p. carried out a t such a rate that the solution was kept boiling 232-235". An additional portion of the product, 13 g., was 4 smoothly. ' white precipitate gradually appeared. The obtained by evaporating the volume of the filtrate to 400 reaction mivture was heated on the stcam-bath for 30 min- ml. Recrystallization of the crude product from water raised utes to insure the completion of thc reaction and then was the melting point to 237-239'. placed in a refrigerator overnight. The product was filtered Anal. Calc'd for C6H8N40: C, 42.9; H, 5.72; N, 40.0. and washed with a small amount of cold absolute ethanol. Found: C, 43.3; H, 5.60; N, 40.0. The yield %-as 109 g. (86.4%), m.p. 221-222'. RecrystallizaPreparation of &amino-l-phenylpyrazolc-4-carboxamide tion from water raised the m.p. t o 222-223'. (SVI, R1 = e&). To 400 ml. of concentrated sulfuric acid Anal. Calc'd for C&N4: C, 49.2; H, 4.9; N, 45.9. Found: cooled in an ice-bath was added, with stirring, 88 g. of 5C, 49.2; H , 4.6; N,46.0. amino-4cyano-1-phenylpyrazole. During the addition, which Preparation of 6-amino-~-cyano-l-phenylpyraaole (IV, required three hours, the inside temperature was maintained R1 = C6H6).T o 88 g. of phenylhydrazine (I, R1 = CoH6) between 10-15'. The mixture was stirred a t room temperin 360 ml. of absolute ethanol was added slowly, with ature until solution was complete. The dark sulfuric acid shaking, 100 g. of cthoxymethylenemalononitrile. After solution then was poured onto crushed ice, and the solution about half of the addition was completed, the solution was was neutralized with concentrated ammonium hydroxide. The carefully heated t o boiling. The remaining ethoxymethyl- reaction mixture, which was allowed t o reach 65-70' during enemalononitrile was added at such a rate as to maintain neutralization, was cooled to room temperature and filtered gentle boiling of the solution. After all the ethoxymethylene to yield 90 g. of yellow crystalline product, m.p. 169-170'. malononitrile had been addea, the solution was gently boiled Recrystallization of thc crude compound from water raised for an additional 30 minutes and finally was set aside over- the m.p. to 172-173'. night in the refrigerator. The product was filtered and washed Anal. Calc'd for CloHloNaO: C, 59.4; €I, 4.95; N, 27.7. with a littlt. ethcr to give 120 g. of crude material, m.p. Found: C, 59.5; H, 4.87; N, 28.1. 138-139'. The compound was further purified by recrystalThe other 1-substituted 5-aminopyrazole-~-carrboxamides lization from water to give white crystals, m.p. 140". were prcpared by essentially the same procedure. Anal. Calc'd for CloIIsN4:C, 65.1; H, 4.4; N,30.4. Found: Preparation of I-alk?jl(aryl)-4-hydroxypyrazolo[S,(i-d]pyrimC, 65.2; €I, 4.4; N,30.8. idines (XVII). See Table 111. 4-Hydroxy-1-niethylpyrazoloPreparation of 5-amino-l-(p-chlorophenyl)-~-cyanopyrazole [S,4-d]pyrimidine (XVII, R, = CH,). A solution of 40 g. o f (IV, R1 = pCl-C6H4).Ethoxymethylenemalononitrile (90 g.) 5-amino-I-methylpyrazole-4earboxamide (XVI, RI = CHI) was added slowly to 500 ml. of hot ethanol containing 105 g. and 100 ml. of C.P. formaniide was boiled gently on a hot of p-chlorophenylhydrnzine (I, R1 = p-Cl-C&). The slow plate for 2 hours. An equal volume of water was added to the cooled mixture which then was set aside in a refrigerator (11) Skipper, Robins, Thomson, Brockman, Schabel, overnight and finallv was filtered. The crude product was and Cheng, Proceedings of the American Association for purified by solution in hot, dilute potassium hydroxide followed by reprecipitation from the hot solution with glacial Cancer Research, 2, 147 (1956). (12) All melting points are uncorrected and were taken acetic acid. Final purification was accomplished by recrystallization from water to give 36 g. of white crvstals, in p. > on a Fisher-Johns melting point apparatus. 300". (13) Huhw, J . Am. Chena. SOC., 2224 (1913). 65, R1 RI I 3 " I I xxxv 1252 CHEKG AND ROBIKS VOL. 21 Anal. Calc'd for Cd3JVrO: C, 48.0; H, 4.30; K, 37.3. tallization from water gave 21.0 g. (49%) of an analytically pure product, m.p. 266-268'. Found: C, 48.1; H, 4.39; N, 37.5. ~-Hydroxy-l-phenylpyrazoEo[S,~-d]pyrimidine (XVII, R1 Anal. Calc'd for C6HiN6:C, 48.3; H, 4.6; K,47.0. Found: = C a s ) . 5-Amino-1-phenylpyrazole-4-carboxamide (15 g.) C, 48.7; H, 4.6; N, 47.3. Method ( 9 ) . To 5 g. of 4-ehloro-l-methylpyrazolo[3,4-d]was heated with 50 ml. of C.P. formamide a t 190-200' for 30 minutes. The cooled solution was diluted with 50 ml. of pyrimidine (XVIII, R1= CHI) was added 70 ml. of absolute water and allowed to stand in a refrigerator overnight. The ethanol previously saturated with dry ammonia gas a t 0'. product then was filtered and washed with water, and re- The mixture was heated a t 160" in a glass-lined bomb for crystallized from water to yield 11.0 g. of small needles, 6 hours. The solution then was evaporated to dryness on a steam-bath and the solid was crystallized from 95% ethanol m.p. 299". Anal. Calc'd for C11H8N40:C, 62.2; H, 3.78; N,26.4. containing a small amount of potassium hydroxide. The Found: C, 62.3; H, 3.78; N, 26.9. yield was 3 g. (68y0), m.p. 266'. &4 mixture m.p. of this prodPreparation of 1 -alkyl(aryl)-4-~hloropyrazolo[S,4-d]pyrimi- and that obtained by Method ( 1 ) showed no depression. uct dines (XVIII). See Table 111. 4-Chloro-I-methylpyrazolo- Both preparations gave identical ultraviolet spectra a t pH 11and pH 1. [3,4-d]pyrimidine (XVIII, R1 = CH3). 4-Hydroxy-I-methyl4-Amino-l-phenylpyrazolo[S,4-d]py~in~idine I X , R, = (S pyrazolo[3,4-d]pyrimidine (XVII, R1 = CH,) (100 9.) wa,s suspended in 600 ml. of phosphorus oxychloride. The C6H5). Method (I). A mixture of 5 g. of 4-chloro-1-phenyl1 mixture was refluxed for two hours after solution had oc- pyrazol0[3,4-d]pyriniidine (XVIII, R = C&5) arid 150 curred (a total of 4 hours). The excess phosphorus oxy- ml. of absolute ethanol saturated with dry ammonia gas a t chloride was distilled from the clear, yellow solution under 0' was heated a t 160" in a bomb for 10 hours. The solution reduced pressure, and the residual syrup was poured very was evaporated to dryness and the residue was recrystalslowly, with vigorous stirring, onto 1 kg. of finely crushed lized from dilute ethanol to u-hich a small amount of potasice. The mixture was allowed to stand for 30 minutes, and sium hydroxide had been added. The J ield \vas 3.2 g. (70%) the whit,e suspension was extracted with et8her (approxi- of white needles, m.p. 210". Method (2). ~-~4mino-4-cyano-l-phenylp~-razole R1 = (IV, mately 6 X 600 ml.). The ethereal extract was washed well with ice-water. After drying the extract over magnesium C6HS) (20 g.) was added to '75 ml. of C.P. formamide. The sulfate for 12 hours, the ether was distilled t o yield 95 g. of solution was boiled gently for 1 hour. To the marm mixture long, white needles, m.p. 97-98'. Recrystallization from was carefully added 200 ml. of water and the solution was cooled overnight. The yield of crude product was 22.0 g., heptane raised the m.p. to 98-99'. Anal. Calc'd for C&ClN4: c, 42.7; H, 2.97; N,33.3. m.p. 208-210". Recrystallization from an ethanol-water mixture raised the m.p. to 210". Found: C, 42.7; H, 2.91; N, 33.3. Anal. Calc'd for CIIHgPiS: 62.5; H, 4.2; N, 33.2. Found: C, /t-Chloro-l-phenylpyrazolo[S,~-dlpyrimidine (XVIII, RI = 33.4. C&,). A mixture of 300 mi. of phosphorus oxychloride and C, 62.4; H. 3.9; K, 44 g. of 4-hydroxy-l-phenylpyrazolo[3,4-d]pyrimidine This product, was identical to that prepared by Method (XVII, Rl = C6H5) was refluxed for three hours. Excess ( 1 ) as judged on the basis of mixture melting points and phosphorus oxychloride was distilled under reduced pres- identical ultraviolet absorption spectra a t pH 1 and pH 11. sure, and the residual syrup was poured, with stirring, onto Other 4-amino-1-substituted phenylpyrazolo[3,4-d]pyrimicrushed ice. The aqueous suspension was extracted with dines ( X I X ) were prepared in a manner similar to Method chloroform. After drying overnight over sodium sulfate the (2) for the preparation of 4-arnino-l-phenylpyrazolo[3,4-d]chloroform was distilled to yield a slightly yellow-colored pyrimidine. 4-Amino-1 -( P-hydroxyethyl)pyrazolo [S,4-d] p yrimzdina product, n1.p. 121-124". This crude product was recryst.al( X I S , R1 = CH2CH20H).To 150 ml. of G.P. formamide lized from hept.ane to give 45 g. of white needles, m.p. 128'. Anal. Calc'd for C11HiClNd: C, 57.3; H, 3.04; N, 24.3. was added 70 g. of 5-amino-4-cyano-l-(~-hydroxyethyl)pyrazole (IV, R1 = CH2CH20H).The solution was boiled Found: C, 57.1; H, 3.04; N, 24.6. 4-Chloro-l-( p-nitropheny1)pyrazolo [3,4-d]pyrimidine for 1 hour and 30 minutes and the warm solution was di(XVIII, R1 = p-NOz-C6H4).To 260 ml. of phosphorus luted with 100 ml. of water. Upon cooling the solution overoxychloride was added 16 g. of finely powdered 4-hydroxy- night, no crystals appeared; theiefore, the excess formamidc I-(p-nitropheny1)pyrazolo [3,4-dlpyrimidine (XVII, R = and water were removed under reduced pressure using a 1 p-NOn-CsH4).The mixture was refluxed vigorously for six steam-bath as a source of heat. To the residue was added hours until solution was finally effected. The excess phos- 200 ml. of water and 30 ml. of conrentratcd hydrochloric phorus oxychloride was distilled off under reduced pressure, acid. The solution was boiled for 15 minutes, treated with and the syrupy residue was pured very slowly, with stirring, charcoal, and filtered. The filtrate was made basic v-ith onto 500 g. of crushed ice. The crude product was only spar- potassium hydroxide and the warm solution was chilled overingly soluble in ether or chloroform. It was filtered with night. The yield of crude product n-as 54.0 g. RccrystallizaRuction and washed well with ice-water until free from acid. tion from water yielded 34.0 g. (42.57,), m.p. 217-219'. The crude compound was dried in air and recrystallized A second recrystallization from R-ater raised the m.p. to from n-heptane to yield 14.0 g. of yellow needles, m.p. 223-224'. Anal. Calc'd for CiH9Xs0: C, 47.0; H, 5.0; N, 39.1. Found: 204-205'. Anal. Calc'd for Cl1H.&1Ns02: c, 48.0; H, 2.20; N, 25.4. C, 47.3; H, 4.9; N, 39.1. Preparation of 1 -alkyl( aryl)-4-nzercaptopyrazolo[S,d-d] Found: C, 47.6; H, 2.32; N, 25.4. Preparation of I-alkyl(aryl)-4-aminopyrazolo[3,4-d] pyrimi- pyrimidines (XX). See Table 111. 4Prlercapto-1-methylpyrdines (XIX). See Table 111. 4-Amino-I-methylpyrazolo- azolo[3,4-d]pyrimidine (XX, R1 = CH3). Method ( 1 ) . (XVIII, R1 = [3,4-d]pyrimidine (XIX, R1 = CHI). Method ( 1). To 100 ml. 4-Chloro-l-methylpyrazolo[3,4-d]pyrimidine CH,) (5 g . ) and 2.5 g. of C.P. thiourea wwc added to 100 of C.P. formamide was added 35 g. of 5-amino-4-cyano-lmethylpyrazole (IV, R1 = CHI). The solution was boiled ml. of absolute ethanol. The mixture was refluxed for 1 for 1 hour and allowed to cool. To the reaction mixture was hour, during which time a white rrybtallirie pi otlurt deposited added 100 ml. of water and the solution was placed in the in the hot solution. The prodiict was filtered and washed refrigerator overnight. After filtration, the crude product with cold 957, ethanol. The yield xas 4 g. (81%), m.p. > was suspended in 300 ml. of boiling water and 20 ml. of con- 300". Anal. Calc'd for CGHGN~S:43.4; H, 3.6; N, 33.8. Found: C, centrated hydrochloric acid was added. The solut.ion was boiled 3 minutes a-ith charcoal and filtered, The hot filtrate C, 43.4: H, 4.0: N, 34.0. iZTethod ( 2 ) .Tetralin (400 ml.) was heated to 16jo,and an was made basic with a solution of sodium hydroxide and allowed to cool. The product cryst,allixed in colorless crystals intimate mixture of 10 g. of finely powdered 4-hydroxy-lpyrimidine (XT'II, I? = CEI,) and :tnd was filtered and wv:ishcd with ice-water. A final recrys- meth~-lpyrazolo[3,4-d] - NOVEMI3ER 1gstj POTEKTIAI. PUfi.INE ANT:IGOhTSTS. VI 1253 50 g. of phosphorus pentasulfide was slowly added to the nolic solution of 5 g. of 4-chloro-l-methylpyrazolo[3,4-d]mixture, with stirring, over a period of 45 minut,es. During pyrimidine. The mixture n-as cooled in an ice-bath for 10 that time the temperature of the mixture was allowed to minutes, thcn allowed to warm up to room temperature, and finally \vas heated gently on a steam-bath for 30 minutes, climb to 185'. The reaction mixt,ure then was heat,ed a t 190195' for six hours with continuous stirring. The solution The fiolution was filtered, and white, silky needles crystallized then was t:ooled overnight and filtered, and the solid was from the filtrate. The erudr product was recrystallized washed n-it,h petroloiim t.ther and dried. The crude mat,eria,l fiom methanol to yield 2.5 g. (,51.2y0), m.p. 105-106". A n d . Cdc'd for C,HsN40: N, t34.2. Found: N, 34.2. then mis : ~ d d e dsloivly to 1000 ml. of boiling watcr. Just ~-Ethox~~-i-phenyIpyrazolo[S,~-d]pyrinzidine (XXVII, R1 enough potnssiiim hydroxide n'as added to effect complrte solution. The solution v a s treated with charcoal and fil- = C6H6, R2 = C&). 4-Chloro-1-phenylpyrazolo [3,4-d]tered and the filtrate vias acidified while hot with acetic pyrimidine (5 g.) (XVIII) was dissolved in 150 ml. of warm acid. The solid was filtered immediat,ely and washed viith absolute ethanol. To this solution, cooled to I O o , was added water to yield 8.0 g. (i2.2vO)of crude product. Reprecipi- 150 ml. of absolute ethanol in which 2 g. of sodium had been tation of this material yielded a product which showed ult,ra- dissolved. The mixture was allowed to warm to room temviolet absorpticn ciirvcs identical with the product obtained perature and then was heated gently on a steam-bath for two hours. The sodium chloride was filtered from the hot by Method ( 1 ). solution, and the filtrate on cooling yielded the crude prodPreparation OJ l-(p,-chlorophenyl)-~-~nercaptopyrazolo[S,4uct. Recrystallization from ethanol gave 3.2 g. of long, dlpyrirnidiize ( S X , It1 = p-CI-C6H:4). 4-Chloro-l-(p-chlorophenyl)pyrazolo[3,4-d]pyrimidine(XVIII, R = p-CI-CoH4) white needles, m.p. 92-94'. 1 Anal. Calc'd for C13H12N40: C, 65.0; H, 5.03; N, 23.3. (5 g.) and 5.0 g. of thiourea was added to 180 ml. of absolute ethanol. Thc~ solution was refliixed for 6 hours. The solid was Found: C, 65.2; H, 5.28; N, 23.1. 4-( p-Bromophenoxy)-l-methylpyrazolo[ SJ-d] p yrimzdine filt,ered and purified by dissolving in hot, dilute potassium hydroxide followed by precipitation with acetic acid. The (XXVII, Rl = CH3, RI = p-Br-CeH4). To a mixture of 5 g. of p-bromophenol was added 5 g. potassium hydroxide yield of white uccdles was 4.3 g., m.p. >300'. Anal. C:rlc'd for C1111?C1S4Fj:C, 50.2; H , 3.7; X, 21.3. and 150 ml. of water. To this solution was added, a little at a time, 5 g. of finely powdered 4-chloro-1-methylpyraxoloFound: C, 50.2: H, 4.0; N, 21.5. [3,4-d]pyrimidine (XVIII, R1 = CH3). The mixture then Other l-sr~-l-~-merca~topyrazolo[3,4-d]pyrimidines listed in Table 111 were prepared in a similar manner from XVIII. was heated on a stem-bath for 30 minutes. A white solid Preparation o j 1-/neth yl-4-methylmercaptopyrazolo[5,4-d]- precipitated from the hot solution. The product was filpyriviidine ( S S I , XI, Rz = CH,). dlethod (1). To 8 g. of tered and recrystallized from methanol to yield 5.5 g. of 4-mercapto-l-methylpyr:izolo[3,4-d]pyrimidine (XX, R1 = white needles, m.p. 167". Anal. Calc'd for CI2H9BrN10:X, 18.4. Found: N, 18.6. CH8), dissolvcd in a solution of 5 g. of potassium hydroxide a n d 100 nil. of water, wa.s slovily added, with Preparation of i-aEkyl(aryl)-4-substitzctedamino-pyrazolostirring, 12 g. of methyl iodide. The mixture was trans- [S,(t-d].pyrimidines(XXVI). See Table IV. The compounds ferred to a separatory-furiIirl and 15 ml. of methanol was listed in Table IV were prepared by either Gentral dfethod added. The solution was shaken vigorously for 30 minutes. ( A ) or General Method ( B ) . At the end of this period a vhite crystalline substance apGeneral Method ( A ) is illustrated by the following specific peared, which was filtered and recrystallized from water. examples: of The yield vias 7 g. (80.7y0) a white crystalline product i-Methyl-~melhylaminopyrazolo[S,4-d]pyrinzidine (XXT'I, whichmelted a t 133". Rl = CH,, RS = H, R = CH,). To a mixture of 70 ml. of d Anal. Caic'd for C7HglS:4S: N, 31.1. Found: N, 31.0. 4OYc methylamine in 50 ml. of 95Yc ethanol was added I 1 Method (2). A mixture of 2.5 g. of 4-mercapt~opyrazolo- g. of 4-chloro-l-methylpyrazolo[3,4-d]pyrin~idine (XVIII, [3,4-d]pyrirnidine,, 2.5 g. of potassium hydroxide, 30 ml. Rl = CH,). The solution was refluxed on a steam-bath for of wat,er, 15 g. of methyl iodide, and 50 ml. of methanol was 8 hours. The rn hite solid which formed in the hot solution refluxed on a stcnm-hsth for 6 hours. Thc product crystal- was filtered after the solution had cooled. Recrystallization lized from the hot solution as yelloar needles. I t was recrys- from methanol yielded 8.5 g., m.p. 200-201". tallized from n-at,er to yield 1.5 g., m.p. 135". The comAnal. Calc'd for C ~ H Q N ~51.5; H, 5.6; 1, C, : 42.9. Found: pound, vhcn mixed with that made from illethod ( I ) , C, 51~2; 5.8; N, 42.5. H, showed no depression iri melting point. 4-(0-3lethylanilino)-1-methylpyrazolo [S,/i-d]pyrimidine illethod ( 3 ) .To a mixture of 10 g. of methyl mercaptan, 5 g. of potassinm hydroxide: and 20 g. of methanol was added, (XXVI, R1 = CH,, R8 = H , R4 = o-CHa-CSH4). A mixture and a little a t a time, 5 g. of finely pondered 4-chloro-1-methyl- of 5 g. of 4-chloro-l-methylpyrazolo[3,4-d]p~~rimidine pyrazolo[3,-L-d]pyrilnidine (XVIII, Ri = CH3). The reac- 4.5 g. of o-toluidine in 200 ml. of absolute ethanol was ret,ion proceeded instantly, and a white preeipita t'e appeared in fluxed on a steam-bath for 5 hours. A m-hite solid crystallized the alkaline sohition. The mixture x i s heated gently on a after the solution was cooled overnight. After recrystallizasteam-cone for 30 minut,es and the solution was cooled and tion from ethanol the product melted a t 104-166', jield filtered. Tht: product recrystdlized from water to give white 4.3 g. -4nal. Calc'd for CI3Hl3N~: , 65.2; H, 5.5; T, 29 3. C needles, m.p. 135". This product, was ident,ical to that prepared by Jlethoda ( 1 ) and ( 2 ) as judged by mixture melting Fonnd: C, 65.2: H, 5 . 5 ; N, 29.2. ~-Hydrazzno-l-niethylpyraeolo[S./i-d] pyrimidine (XXVI, R, point d a h :md identical ultraviolet absorption spectra. Preparation of ~-(p-chlorophen?~lmercapto)-l-wiethylpyra- = CH3, R3 = H, R4 = P I " 2 ) . To a mixture of 300 ml of zolo[S,/i-d]p~irimidine (XXI, R1 = CHI, R, = p-Cl-CaH4). 95ycethanol and 90 g. of 85y0hydrazine hydrate was added 30 g. of finely powdered 4-ehloro-l-methylpyrazolo[3,4-d~ p-Chlorothiophenol (6.5 g.) and 7.5 g. of 4-chlororl-methylpyrazolo [3,4-d]pyrimidine (XJTII, RI = CH3) were added pyrimidine. 4 xhite precipitate formed instantly. The mixto 200 ml. of anhydrous benzene and the solution was ture was warmed on a steam-bath for ten minutes and filrefluxed for 4 hours. The mixture solidified on cooling to tered. The product was recrystallized from 507, ethanol to give a product, m.p. 153-156'. Recrystallization from ben- yield 29 g. of white needles, m.p. 246.5-247'. Anal. Calc'd for C6H,Ns: N, 51.1. Found: N, 50.8. zene raised the m.p. t,o 156-157", yield 7.2 g. Anal. Calc'd for C12H,C1N4S: , 20.2. Found: N, 20.0. S 4 9 l e t h y l h ydrazino-1-phtnylpyrazolo[S,4-d]pyrznudine 4 Preparation of 4-alkoxy-l-alkyl(aryl)pyruzololS,4-d]pyrimi- (XXVI, Rl = CSH5, R3 = H , R = NHCH?). A solution of 6 g. dine (XXVII). See Table 111. ~-Methoxy-i-methylpyruz- 5 g. of 4-chlo~o-l-phenylpyrazolo[3,4-d]p~rimidine, of olo[J,4-dlpy-imidine (XXVII, R1 = CHI, R, = CH3). One methylhydrazine, and 200 ml. of methanol was heated on gram of sodium was dissolved in 50 ml. of methanol. To the steam-bath until the volume of the solution had heen this solutior was nddpd, very carefully, 50 ml. of a metha- reduced to 50 ml. The solution, upon cooling, yielded white I254 CHENG AND ROBINS VOL. 21 Anal. Calc'd for C I ~ H Z ~ N64.5; H, 8.9; N, 26.8. Found: C, ~ : C, 64.0; H, 9.1; N, 26.7. 4-Furjurylamino-1-methylpyrazolo [S,4-d] pyrimidine 1 (XXVI, R = CH3, R3 = H. Rg = C&O). 4 mixture of 5 g. of 4-chloro-1-methylpyrazolo [3,4-d]pyrimidine (XVIII, R = CH,) and 4 g. of furfurylamine dissolved in 60 ml. of 1 absolute ethanol was heated on the steam-bath for 8 hours. The solvent then nas alloKed to evaporate to leave a glassy, gummy substance which mould not crystallize after long standing. This substance was treated with dilute potassium hydroxide and the solution was extracted n-ith chloroform. A light-yellow residue, which was obtained after the distillation of the excess chloroform, was rerrystallized from hcnzenc to yicld 6.1 g. of white needles, m.p. 150". Ana/. Calc'd for C1lH1lP\T~O: 30.6. Found: i , N, Y 30.7. &-Cyclohexylamino-1-methylpyrazolo[,?,&-dl p?lrinzidine (XXVI, Rl = CH3, R3 = H, R4 = C&). A misturc of 10 6 g. of 4-chloro-l-methylpyrazolo[3,4-d]pyrimidine, g. of cyclohexylamine, and 120 g. of methanol was refluxed on a steam-bath for 4 hours and finally was evaporated to dryness. The product mas crystallized by treating the residue with a mixture of ether and methanol. Reciystnllization from methanol gave 4.0 g. of white needles, m.p. 05-96O. Ana/. Calc'd for CI2H17N5: 30.3. Found: N, 30.3. K, 4-n-Butylaniino-1-methylpyrazolo[SJ4-d] pyrimidzne (XXVI, R, = CHs, R3 = H, R4 = n-CdH9). To 40 g. of n-butylamine in 120 ml. of methanol was added 13 g. of 4-c~hloro-l-methyl\cH~-cH~/ was added 8 g. of 4-chloro-l-(p-chlorophenyl)pyrazolo[3,4- pyrazolo[3,4-d]pyrimidine.The solution TTXS refluxed on a dlpyrimidine (XVIII, R1 = p-C1-C6H4)and 8 g. of %mor- steam-bath for 8 hours and then was evaporated to dryness. pholino-n-propylamine. Bfter boiling on a steam-bath for The rcsidue was extracted with boiling benzene, and a small 40 minutes, a solid appeared which was filtered and recrys- amount of heptane was added to the hot filtrate xhich tallized from 2-ethoxyethanol to yield 10.0 g., m.p. 182- crystallized on cooling the solution to givc 12 g. of white needles, m.p. 87-88'. 184'. Anal. Calc'd for CIOHIENL: X, 34.2. Found: N, 34.1. Anal. Calc'd for C18H21C1Nt,0: 22.5. Found: N, 22.8. N, 4 4 N-Mdhylanilino)-l-phenylpyrazolo[3,4-d]pyrimidine 1-( p-Chlorophenyl)-4-(2'-N,N-diethylaminoethylanzino)(XXVI, Itl = C&, R3 = CH3, R4 = CaH5).A solution of pyrazolo[S,&-dlpyrimidzne [ XXVI, R1 = p-Cl-C&, R3 = (XVIII, H, R4 = CH2CH2S(C2116)2]. 2.5 g. of 4-chloro-l-phenylpyrazolo[3,4-d]pyrimidine 4-Chloro-l-( p-rhlorophrny1)R1 = C6HS) and 2 g. of N-methylaniline dissolved in 200 pyrazolo[3,4-d]pgrimidine (5 9.) was added to a solution of ml. of absolute ethanol was heated on a steam-bath for 10 300 ml. of absolute ethanol and 5 g. of 2-N,S-dicthylaminohours. On cooling, colorless needlcs crystallized slomly from ethylamine (8-diethylaminoethylamine). T h r solution was the purple solution. The product was recrystallizcd from refluxed on a steam-bath for 12 hours and then was evapoethanol to yield 2.2 g. (64.57,), m.p. 115-116'. rated to dryness. Thc residue was treated n ith cold bcnzene Anal. Calr'd for CisHldNa: 71.7; H, 5.0; N, 23.3. Found: to which had been added a small amount of methanol, and C, C, 71.2; H, 4.7; N, 23.3. thc product slow~ly solidified in a refrigcrator. The solid was l+-(~-Hydroxyethylhydrazino)-1-methylpyrazolo [9,4-d]- recrystallized from m t e r and a small amount of methanol pyrimidine (XXVI, Rl = CH,, R3 = H, Rg = NHCH2CH2- to yield 4.5 p. of white needles, m.p. 105-106". OH). To 100 ml. of methanol was added 9 g. of 707, 0-hyAnal. Calc'd for C17HZ1C1N6: 24.4. Vound: N, 21.4. N, droxyeth3-lhyclrazine and 8.5 g. of 4-chloro-1-methylpyra4-( 2'-N-~-Hydroxyethylaminoethylamino)-l-( p-chlorophenzolo[3,4-d]pyrimidine. The mixture was refluxed on a steam- yl)pyrazo/o[S,4-d]pyrimidzne [XXVI, RI = p-Cl-CeH4, Ra = bath for 6 hours. The solid which formed on cooling was H, R4 = (CH2)2-KH(CH2)20H]. solution of 8 g. of 4A recrystallized from mcthanol to yield 12 g. of white needles, chloro-l-(p-chlorophenyl)pyrazolo[3,4-d]pyrimidincJ g. 8 m.p. 133-134'. of 2-K-8-hydroxyethylaminoethylamine (S-aminoethylethAnal. Calc'd for C8H12N60: N, 40.3. Found: N, 40.1. anolamine), and 150 ml. of mcthanol was refluxed on a T this particular preparation methanol was found to be steam-bath for three hours and finally was evaporated to n much superior to ethanol as a reartion solvent. When the dryness on the steam-bath. The residual product was rereaction v a s carried out in ethanol, no product could bc crystallized three times from a mixture of benzene and isolated. methanol. There finally was obtained 4 p. of pure product General Method (B) for the preparation of 1-alkyl( aryl)-4- n-hich melted at 154-155". is X, substituted aminopyrazolo[3,4-d]pyrimidines illustrated Anal. Calc'd for ClSH1~C1N~O: 25.2. Found: N, 25.2. by the following specific examples: Preparation of 1-methy/pyrazolo[SJ4-d ]pyrimidine (XXV, I-Methyl-&-( ',1',3',S'-tetramethyl-n-hulylamino)pyrazolo- Rl = CHI) 4-Chloro-1-methylpyrazolo [3,4-d]pyrimidine 1 (XVIII, Rl = CH,) (5 g . ) was added to a solution of 150 [S&d]pyrimidine (XXVI, R1 = CH,, R3 = H, R = 4 C8H17). To 7 g. of 4-chloro-1-methylpyrazolo [3,4-d]pyrimi- ml. of methanol and 4 ml. of concentrated ammonium hydine (XVIII, R1 = CH3) dissolved in 100 ml. of methanol droxide. To this solution was added 1.5 g. of 5 7 , palladiumwas added, with stirring, 12 g. of 1,1,3,3-tetramethyl-non-charcoal. The mixture was shaken on a hydrogenator a t butylaminc. The mixture was heated on the steam-bath for 20 lb. per sq. in. pressure until the uptake of hydrogen 8 hours and finally was allowed to evaporate to a syrupy ceased (six hours was required). The solution then was filliquid. To the crude product was added 40 ml. of absolute tered and the black residue was extracted with 100 ml. of ethanol. The mixture was boiled, treated with charcoal, and methanol. The combined methanolic solution was evapoheated with a small amount of diatomaceous earth. To the rated to dryness on a steam-bath. The product was recrystalfiltrate was added 20 ml. of water and the product crystal- lized from benzene and then was sublimed twice a t 130" lized after standing two weeks in the refrigerator. The yield under reduced pressurc to givc 1 g. of white nerdles, m.p. of white needles, m.p. 132-133.5", wns 9 g. 125-126". crystals. Recrystallization of the crude product from ethanol gave 4.1 g., m.p. 153-155'. Anal. Calc'd for C12H12N6: 60.0; H, 5.03; N, 35.0. C, Found: C, 60.2; H, 5.01; N, 34.3. 4-( o-Ch1oroanilino)-I-phenylpyrazolo3,4-d]p yrimidine [ (XXVI, R1 = CH3, R3 = H, R4 = o-Cl-C&). 4-Chloro-lphenylpyrazolo[3,4-d]pyrimidine (5 g.) and 11 g. of ochloroaniline were added to 200 ml. of absolute ethanol. The solution was boiled gently on a steam-bath for 4 hours. A solid prodirt separated from the hot solution. Recrystallization from 2-ethoxyethanol gave 4.5 g. of white needles, m.p. 157-158'. Anal. Calc'd for C17Hl2C1Xa: 63.6; H,3.77; N, 21.8. C, Found: C, 63.0; H, 3.72; N, 21.9. 4-Benzylamino-1-methylpyrazo/o[3,4-d]pyrimidine (XXVI, R1 = CH3, R3 = H, R4 = CH2-C6H5). Benzylamine (10 g.) and 8 g. of 4-chloro-1-methylpyrazolo [3,4-d]pyrimidine were added to 200 ml. of absolute ethanol, and the solution was heatrd for 8 hours on the steam-bath. The solid, which separated on cooling, was recrystallized from ethanol to give 11 g. of white leaflets, m.p. 158-159.5'. Anal. Calc'd for Cl3H13N5:N, 29.3. Found: N, 29.1. 1-( p-Chlorophenyl)-~-(S'-morpholzno-n-prop~lamino)p yrazolo[S,&-d]pyrzmidine(XXVI, R1 = p-C1-C6HgJ R3 = H, /CHz-CH*\ R, = n-C3H6-N 0). To 160 ml. of methanol NOVEMBER 195G POTEKTIAL PURINE rlNTAGONISTS. VI 1255 Preparation of 5-a?nano-i,S-dimethylpyrazole-4-carboxamide Anal. Calc'd for CsHeNr: C, 53.7; H, 4.50; X, 41.8. Found: (XXXIII, RI = CH,). 5-Amino-4-cyano-1,3-dimethylpyraC, 53.9; H, 4.55; N, 41.9. Preparation of 1,6-dimethylpyrazolo[3,4-d]pyrimidine-C- zole (XXXII, RI = CH,) (50 9.) was added portionwise to thione (XXIV, R1, Rz = CH3). A mixture of 8.6 g. of phos- 150 ml. of concentrated sulfuric acid. The isolation and py- purification process was similar to that employed for 5phorus pentasulfide, 4 g. of 1,5-dimethylpyrazolo[3,4d] Thus 42 g. (74y0) rimidone-4 (XXIII, R1, R = CHa), 45 ml. of o-xylene, and amino-1-methylpyrazole-4-carboxamide. g of white needles were obtained, m.p. 203.5-204.5". 45 ml. of toluene m s refluxed for 3.5 hours. The mixture, Anal. Calc'd for CsHloNp0: C, 47.0; H, 6.5; N, 36.3. after cooling overnight, A as filtered. The solid was recrystallized from 120 ml. of hot water to give light-yellow Found: C, 47.3; H, 6.5; N, 36.2. Preparation of 1,3-dimethyl-4-hydroxypyrazolo [5,4-d]pyrimneedles, m.p. 242-243" (sublimed a t 210"), yield 2.0 g. Anal. Colc'd for C?HgN4S: C, 46.4; H, 4.44; N, 31.1. idine (XXXV, R1 = CH,). -4mi re of 35 g. of 5-aminoPound: C, 43.1; H, 4.56; N, 31.0. 1,3-dimethylpyrazole-4-carboxam (XXXIII, Ri = CH3) and Preparotion of 5-am~no-i-phen~ylpyrazole-4-carboxaniide 120 ml. of formamide was boiled on a hot plate for 4 (XV) from ci-hydroxy-l-phenylpyrazole-4-ethylcarboxylate (X). hours. An equal volume of water was addcd to the mixture A mixture of 20 g. of 5-hydroxy-1-phenylpyrazole-4-ethyl- and the R hite solid was filtered after standing overnight. carboxylate, 5 g. of phosphorus pentachloride, and 500 ml. The product was recrystallized from ethanol to give m.p. of phosphorus ovychloride was refluxed vigorously for 10 276.5'. The yield was 27 g. (72.5%). hours. All ihe excess phosphorus oxychloride was distilled Anal. Calc'd for CiH8N40: C, 51.3; 11, 4.0; N, 34.1. off under rcduccd pressure. The residue, without purifica- Found: C, 51.5; H, 4.7; K, 34.0. tion, was transferred to a container with 150 nil. of satuPreparation of 4-amino-3-nicfhylpyrazolo [3,6-d]pyriniidine rated alcoholic ammonia. The mixture was heated a t 180' in a (XXXI). A mixture of 50 g. of 5-amino-4-cyano-3-methylbomb for G hours. The solution was evaporated to dryness, pyrazole (XXX) and 100 ml. of formamide was boiled on a and the residue then was recrystallized from 957, ethanol. hot plate for 45 minutes. The isolation and purification proA small axr-ount of product mas obtained which melted a t cedure was followed as recorded for the preparation of 41G5-168". I t was recrystallized twice more from mater to aminopyrazolo [3,4- d ] pyrimidine3 from 3-amino -4- cyanoraise the melting point to 171-172'. The yield of white pyrazole and 20 g. (437,) of the purified product was obcrystals was 0.5 g. A mixture of this compound and that tained, m.p. > 300". obtained by the hydrolysis of 5-amino-4-cyano-1-phenylAnal. Calc'd for C&7N5: C, 48.4; H, 4.7; N, 4G.9. Found: pyrazole (IV, Rl = C&t6)did not lower the melting point. C, 48.6; H, 4.8; N, 4G.8. Anal. Colc'd for CloHloN40: N, 27.7. Found: N, 27.9. Preparatzon of Q-amino-l,S-dimefhylpyrazolo[S,4-d]pyrinzPreparation of methylethoxymethylenemalononitrile(XXIX ). zdine (XXXIV, R1 = CH3). rl mixture of 50 g. of 5-aminoMalononitrile (81 g.), 200 g. of triethyl orthoacetate, and 4-cyano-1,3-dimethylpyrazole (XXXII, R1 = CHs) and 270 g. of acetic anhydride %-eremixed in a 2 1. three-necked, 100 ml. of formamide was boiled on a hot plate for 45 minround-bottom flask. The mixture was refluxed for 3 hours. utes. The isolation and purification procedure was identical During the prriod the color of the solution changed from to that employed in the preparation of l-(P-hydroxgethyl)light yclloa to dark hrown. The solvents then were removed 4-aminopyrazolo[3,4-d]pyrimidine (XIX, R, = CH2CH2by distillation at reduced pressure. The residue, which solidi- OH). The yield of product was 32.0 g. (53.47,), m.p. 203filtered and washed with a little cold 204". This compound vas recrystallized from m-ater as the fied on cooling, w a ~ ethanol to give nhitc c stals, m.p. 88.5-89.5'. The yield monohydrate n hich lost matcr of hydration when heated was 40 g. (83.77,). Rec stallization from ethanol did not at 140'. change the melting point. Anal. Calc'd for C711sN5.1120:C, 4G.G; H, 6.1. Found: Anal. C ~ l c ' d for C ~ H S K ~ O : G1.7; H, 5.9; N, 20.6. C, C, 46.5; H, 5.0. Found: C, (i2.0; €-I,5.G; N, 20.8. -4fter heating a t 140" it had: Anal. Calc'd for C7H9?iS: Preparation of 5-amino-4-cyano-S-methylpyrazole (XXX). K, 43.0. Found: N, 43.4. To 35 g. of 35% hydrazine hydrate in 20 ml. of ethanol was Preparation of 1,5-dimethylpyrazolo[S,/t-d]pyrimidone-4 added 50 g. of methylethoxymethylenemalonitrile (XXIX), (XXIII, R1, = CH,). Method (1). T o 30 ml. of water Rz a little a t a 1 ime, with outside cooling. The mixture then was was added 3 g. of potassium hydroxide, 5 g. of l-methyl-4heated on the stcam-bath for 2 hours. The solution was hydroxypyrazolo[3,4-d]pyrimidine (XVII, R1 = CH3), diluted n'itli 100 ml. of water and allowed to cool. The 10 g. of methyl iodide, and 100 ml. of methanol. The solucrude product, m.p. 160-163", was filtered and recrystallized tion was shaken for 30 minutes with occasional cooling. from ethanol and water to give white needles, m.p. 163", Then it was allowed to stand a t room temperature for 1 yield 43 g. ( 0 G : ' C ) . hour followed by refluxing on a steam-cone for 4 hours. Anal. Calc'd for C,H,NI: C, 49.1; H, 5.0; N, 45.9. Found: The solid, which separated from the alkaline sohition on C, 49.3; H, 5.8; N, 45.9. cooling, was recrystallized from methanol to yield white Preparation of 5-amino-~-cyano-l,5-dimethylpyrazole needles, 4.1 g. (77yc), m.p. 193-195" (sublimed a t 130"). (XXXII, R , = CHI). To GO g. of 987Gmethylhydrazine in Anal. Calc'd for C;H8N40: N, 34.1. Found: N, 33.9. 300 ml. of ethanol was added 96 g. of methylethoxymethylMethod ( 6 ) . To a solution of 25 g. of 4-hydroxypyrazoloenemalononitrile ( X S I X ) . The isolation and purification [3,4-d]pyrimidine,330 ml. of mater, and 2.5 g. of potassium procedure v a s carried out in the same fashion as for the hydroxide was slowly added 10 g. of methyl iodide in 50 ml. White of methanol. Thc solution was refluxed gently for 5 hours on preparation of 5-amino-4-cyano-I-methylpyrazole. needles werci obtained, m.p. 194", yield 75 g. (87%). a water-bath and then was evaporated to dryness. The criide Anal. Calc'd for CaHsN4: C, 53.0; H, 5.9; K,41.1. Found: compound was recrystallized from water to give m.p. C, 53.5; H, (1.3;T 41.1. I, 190-193". Another recrystallization from water raised the Preparation of 6-amino-4-cyano-3-methyl-1-phenylpyrazoE melting point to 193-195". The final yield was 0.3 g. This (XXXII, Rl = C6Hs).Methylethoxymethylenemalononitrile product was identical to thnt prepared by Method ( 1 ) as (50 g , ) was slowly added to 45 g. of phenylhydrazine dis- judged by mixture melting point data and identical ultrasolved in 150 ml. of ahsolute ethanol. The reaction proceeded violet absorption spectra. in a similar manner as for the preparation of 5-amino-4Preparatzon of 4-dimethylamino-I-niethylpyrazolo[S,4-d] cyano-I-phenylpyrazole (IV, R1 = CsHS). The crude pyrimidine (XXVI, R,, R,= CH3). Method ( 1 )4-ChloroR3, product, yield 58 g. (S070), melted a t 131-132'. Recrystall-niethylpyraaolo[3,4-d]pyrimidine (XVII, R1 = CHI) lization from water gave long needles, m.p. 132-133'. (12 g.) and 150 g. of aqueous dimethylamine were Anal. Cnlc'd for CI1HloN4: C, D G . 3 ; H, 5.1; N, 28.2. mixed in 50 ml. of ethanol. The solution was refluxed on a Found. C, 65 7 ; H, 5 . 2 ; N, 28.3. steam-bath for tn-o hours and then was evaporated to dry- ness. The d i i t e solid was recrystallized from ethanol t o yield 10 g. (95%) of u-hite crystals. Sublimation gave long, I\ hite needles, m.p. 132". Anal. Calc'd for CsHllNs: N, 39.5. Found: N, 39.5. Method ( 2 ) .One gram of 4-dimethylaminopyraxolo[3,4-d]pyrimidine3 was dissolved in a solution of 75 ml. of methanol, 20 g. of methyl iodide, 2 g. of potassium hydroxide, and 10 ml. of water. The solution was gently refluxed on a water-bath for 8 hours and then ivas evaporated to dryness. The white solid was rerrystallized from absolute ethanol to yield white crystals, 0.4 g., m.p. 130-131". This compound was identical to that made by Method ( 1 ) as judged by mixture melting point determination and comparison of ultraviolet absorption spectra. LASVEGAS, NEWMEXICO