| 摘要 |
<p>1,232,758. 5 - Amino - 6 - chloro - 1H - imidazo[4,5-b]pyrazin-2-ones. MERCK & CO. Inc. 25 Aug., 1969 [31 Aug., 1968], No. 42184/69. Heading C2C. 5 - Amino - 6 - chloro - 1H- imidazo[4,5 - b]- pyrazin-2-ones of the general formula wherein R and X 1 are each a hydrogen atom or a C 1-5 alkyl group, X 2 is a hydrogen atom or a C 1-5 alkyl, C 1-5 alkoxy-C 1-5 alkyl, monocyclic aryl (optionally halo-substituted), pyridyl or R 4 R 5 N-C 1-5 alkyl group, in which R 4 and R 5 are each a C 1-5 alkyl group or R 4 R 5 N is a saturated 5- or 6-membered heterocyclic ring optionally containing an NH or N-C 1-5 alkyl group or an oxygen atom, are prepared by refluxing a solution of a 2,5-diamino-3- (alkoxycarbonylamino or ureido)-6-chloropyrazine of the general formula wherein Y is an amino, C 1-5 alkylamino, di- (C 1-5 alkyl)-amino or C 1-5 alkoxy group. 2,5 - Diamino - 3 - [alkoxycarbonylamino or ureido)-6-chloropyrazines of the second general formula above are prepared by reaction of methyl 3 - amino - 5,6 - dichloropyrazinoate with an amine of the general formula X 1 X 2 CHNHR, alkaline hydrolysis of the resulting methyl 3,5-diamino- 6-chloropyrazinoate of the general formula concomitant decarboxylation and nitration of the 3,5-diamino-6-chloropyrazinoic acid of the general formula so formed, reaction of the resulting 2-nitro-3,5- diamino-6-chloropyrazine of the general formula with (a) a urea of the general formula H 2 NCON(R1) 2 , wherein R<SP>1</SP> is a hydrogen atom or a C 1-5 alkyl group, (b) a chlorocarbonyl compound of the general formula ClCOY, (c) a di- (C 1-5 alkyl)carbonate or (d) an alkali metal cyanate and hydrogenation of the 2-nitro-3- (alkoxycarbonylamino or ureido) - 5 - amino - 6- chloropyrazine of the general formula thus produced in the presence of a catalyst.</p> |
