MAY
1956
COMMUNICATIONS
599
We have found that when 4,5-diaminopyrimidines are refluxed with mixtures of alkyl orthoformates and carboxylic acid anhydrides,7@ mixtures of purines and K-acylpurines are formed. Methyl, ethyl, and propyl orthoformates and acetic, propionic, and butyric anhydrides have been INSTITUTE OF APPLIED KYOSUHE TSUDA used successfully; evaporation of the excess MICROBIOLOGY SHIGENOBU OXUDB reagents leaves a residual mixture of purine and NUNIVERSITY OF TOKYO HONGO, TOKYO, JAPAN acylpurine, the acyl group deriving from the PHARMACKUTICAL INSTITUTE SEITARO S14EKI anhydride. The acylpurine is hydrolyzed to the UNIVERSITY OF KYUSHU SHINICHIIKURA corresponding purine by action of dilute aqueous FUKUOK.4, J A P A X base (without heating and for limited timc with T.4gAMIXE RESE-lRCH YOSHINOBU SATO L 4BOR ITORY HIROSHI MISIIIMA chloropurines). SANHYO CO., LTD. In this wty 4,5-~lizlmiiiopyrirnidiriesbearing :kt SHIN kG.IW 2, rrOKk 0,JAPI N the 2- and 6-positions amino, chloro, dimothylReceived March 19, 1956 amiiio, hydrogen, hydroxyl, methyl, and methylthio suhstituents give the corresponding purines in good yield. This appears to be a general synthetic route to purines. It also allon-s for the ready isotopic labeling of purines by using esters of carbon1al)cled orthoformate. 4,5 - Diamirio - G - dimethylamino - 2 - (methyl thio)pyriniidinel* (I),0.500 g., 5 ml. of ethyl orthoformate, and 5 ml. of acetic anhydride, refluxed 21/4 hrs., the solution evaporated in vacuo, the residual G-dimethyIamin0-2-(methylthio)puriiie~~ A New Synthesis of Purines (11)and N-acetyl-6-dimethylamino-2-(methylthio)Sir: purine heated 5 min., steam-bath, with 10 ml. of Classical chemical purine syntheses, which in- 1 S sodium hydroxide, and brought to pH 3.8 with volve the cyclization by pyrolysis of 4-amino-5- acetic acid, yielded 0.428 Q. (82Yo) of 11, m.p. formamidopyrimidinesl or modifications such as 278.5-281 O (dec.), m.p. 283-286.5' (dec.) from cyclization of 4,5-diaminopyrimidine sulfate salts sodium hydroxide followed by acetic acid. Calc'd for by means of boiling formic acid or formamide,2 Cs€I,,N5S:C, 45.9; H, 5.30; N, 35.5; S, 15.3.(Found: have been shown to fail when applied to the coii- C, 46.2; 13, 5.55; S , 33.7: 8, 15.4). version of chloropyrimidines to chloropi~rines.2b,3,". Similarly, I \vas cyclized to I1 by refluxing ethyl Rather, all chloropyrines described in the literature orthoformate-propionic anhydride (76% yield), have been synthesized by chlorination of puri- ethyl orthoformate-hutyric nnhydride (23% yield), 1iones,~s6 a procedure which is often unsatisfactory. methyl orthoformate-acetic anhydride (80% yield), Since chloropurines are important intermediates :tiid propyl orthoformate-acetic aiihydridc ((367, for the synthesis of natural and unnatural puriiic yield) nucleosides6a ne\\ synthesis of purines was sought. 2,4,5-Triamin0-6-pyrimidinol,~~ condensed with ethyl orthoformate and acetic anhydride, gave after hydrolysis 64% of guanine hemisulfate hydrate;I2A",',. 248 mp ( E 12,400);A:&, NaoH (1) cf. (a) Gabriel and Colman, Ber., 34, 1234 (1901). 273 nip ( E (3,760).
( e 16,500). By mixed fusion of VI aiid its picrate with nordehydro-a-matrinidine and its picrate, no melting point depression was observed, and there was good agreement between their infrared spectra.
(b) Traube, Ber., 37, 4544 (1904). (c) Isay, Ber., 39, 250 (1906). (2) (a) Bendich, Tinker, and Brown, J . d m . Chem. SOC., 70, 3109 (1948).(b) Robins, Dille, Willits, and Christensen, J . Am. Chern. Soc., 75,263 (1953). (3) Bendich, Russell, and Fox, J . Am. Chern. SOC.,76, 6073 (1954). (4)Robins, Dillc, and Christensen, J . Org. Chenz., 19,030 (1954). ( 5 ) Cj. (a) Fisher, Ber., 28, 2480 (1895). (b) Fisher and Ach, Ber., 30, 2208 (1897). (c) Adams aiid Whitmorc, J . Am. Chem. SOC.,67, 1271 (1945). (d) Davoll and Lowg, J . Am. Chem. SOL,73,2936(1951).(e) Robins and Christensen, J . Am. Chem. Soc., 74, 3624 (1952). (6) cf. (a) Fisher and Helferich, Ber., 47, 210 (1914). (b) Davoll, Lythgoe, and Todd, J . Chem. Soc., 967, lG85 (1948).(c) Davoll and Lowy, J . Am. Chem. SOC.,74, 1563 (1952). (d) Brown and Wcliky, J . Bzol. Chem., 204, 1019 (1053).
(7) Albeit, Brown, and Checseniari, J . Chem. SOC.,474 (1951), converted 2-aminopyrazine-3-carboxamide to 4hydroxypteridine 11y I rfluxing ethyl orthoformatc and acetic anhydride. (8) After completion of this investigation Richter and Taylor, Angew. Chem , 67,303 (1955),desciibed the cyclization of amiriomalonamidamidine dihydrochloride by ethyl orthoformate and acetic anhydride to produce hypoxanthine. (9) Montgomery, J . A m . Chem. SOC, in press, has independently found that chloro-4,5-diaminopyrimidines are cyclized to chloropurines hy ethyl orthoformateacetie anhydride (private communication). (10)Baker, ,Joseph, and Schauh, J Org ('henz , 19, 631 (1954). (11)Trauhe, Ber , 33, 1371 (1900) 112) Cavalieri, Bendich, T i n l m , .md 13ionn, J . C'hem. SOC.,70, 3875 (1948).
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COMMUNICATIONS
4-Chlor0-5,G-diaminopyrirnidine~~ gave, after hydrolysis, 72% of 6-chlorop~rine,~ m.p. 178-180" (dec.). Calc'd for CsH3ClW4: C, 38.8; E?, 1.96; C1, 22.9. (Found: C, 39.0; H, 2.25; C1, 22.7; N, 36.6.) 4,5-Diami1io-2,6-dichloropyrimidine'~ (111) gave, after hydrolysis, 89% of crude 2,B-dichlorpurine (IV), m.p. 16G-174" ; colorless crystals, m.p. 180181.5", from water. Calc'd for C6H2C12K4:C, 31.8; H, 1.07; C1, 37.5; N, 29.6. (Found: C, 31.8; H, 1.46; C1, 37.4; N, 29.2); A",',. 250 mp (inflection, E 3,7801, 274 mp ( e 8,600) ; A%:. 252 mp (inflection, E 3,400), 274 mp ( E 8,100); NaoH 281 mP ( E 8,290). The condelisation product from 111, extracted with boiling heptane and chloroform, left 20% of IV, m.p. 173-175". The heptane solution yiclded 10% of crude N-acetyl-2,G-dichloropuriiie, m.p. 132-155". Calc'd for C7H4CLN40. C, 36.4; H, 1.74, C1, 30.7; N, 24.2. (Found. C, 36.6; H 2.13; C1, 30.5; N, 25.4; A",',. H C ~257 mp (inflection, e 6,150), 273 mp ( E 8,120); A":, 255-262 mp (plateau, e G,940), 272 mp ( E 7,590); A",',. NaoH 281 mp ( E S,550). 4-Chloro-5,G-diamino-2-methylpyrimidine,0300 g., gave 0.056 g. of a mixture of 6-chloro-2-methylpurine14 (Vj and N-acetyl-6-chloro-2-methylpurine, hydrolyzed to yield 0.470 g. (88%) of V as colorless crystals, m.p. 206-207" (dec.), m.p. unchanged from water. Calc'd for CsH&lN4: c, 42.7; H , 2.99, C1, 21.0; N, 33.2. (Found: C, 43.2; H, 3.13; C1, 21.0; N, 33.4). 3,5-Diamiiio-G-dimethylaminopyrimidine, 0.500 (13) Bitterli and Erlenmeyer, Helv. Chim. Acta, 34, 835 (1951). (14) Hitchings and Elion, U. S. Patent 2,697,700 (Dec. 21, 1954), not characterized. (15) Elion, Burgi, and Hitchings, J. Am. Chem. Soe., 74, 411 (1952).
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21
g., gave 0.729 g. of a mixture of G-dimethylaminopurinelo (VI) and N-acetyl-6-dimethylaminopurine (VII), recrystallized from ethanol to give 0.134 g. (20%) of VII, m.p. 129-130" ; ethanol filtrate gave, after hydrolysis, 0.353 g. (66%) of VI, m.p. 256.5257" from chloroform and ethyl acetate-hexane. Calc'd for C,H9K6: C, 51.5; H, 5.56; N, 42.9. (Found: C, 51.7; H, 5.99; N, 42.8.) 2- Methyl -4,5 -diamine- 6 -dimethylaminopyrimidine gave, after hydrolysis, G-dimethylamino2-methylpyrine, m.p. 285-287" from ethanol. Calc'd for C8H11N5: C, 54.2; H, 6.26; N, 39.5. HC1282.5 (Found: C, 54.5; H, 6.44; N, 39.8); NaoH mp ( E 17,100); : : :A 275 mp (e 19,GOO); A:,&. 282.5 mp (e 17,100). 4,5-Diamiiio-2- (methylthio)-6-pyrimidino116 gave, after hydrolysis, 64% of 2-(rnethSlthio)-C,-r,urinol, l7 m.p. 278", m.p. 289-291" from water (1,'4 I b O ; Calc'd for C ~ H B N ~ O S * ' / ~ H C,~ O 38.6; : H, 3.51; N, 30.0; S, 17.2. Found: C, 38.8; H , 3.82; S , HC1 268 nlp ( e 14,500); 28.4; S, 16.8); A",',. 259 mp (e 11,700); A ,x:& lV 274 m p ( e 11,200). MEDICINAL CHEMICAL I ~ E ~ E ASECTION, RCH RESEARCH DIVISION, AMERICANCYANAMID COMPANY, LEDERLE LABORATORIE~, PEARLRIVER,NEW YOILK. LEONGOLDRIAN JOSEPH W. RIARSICO ALBERT L. G A Z Z O L ~
Received March 30, 1956
(16) Johnson, Johns, and Heyl, A m . C h e m J., 36, 160 (1906). (17) Mentioned by Elion, Hitchings, and VanderWerff, J. Biol. Chem., 192, 505 (1951), but neither synthesis nor characterization given.
