Purine 6-benzylthio

Der Ersatz einer Benzylthio-Gruppe in N-Heterocyclen wie z. B. Purin-Derivaten kann durch Erhitzen in waBrigem Hydrazin (- 6-Hydrazino-Derivat, 88%) und anschlieBendes Kochen in Wasser in Gegenwart von Raney-Nickel erfolgen (70%)1 z. B. ... 

Purine, 2-acetamido-6-benzylthio-dihydrofuranylation, 5, 536 Purine, 8-alkenyl-synthesis, 5, 537 Purine, 6-alkoxy-oxidation, 5, 539 Purine, l-alkoxy-9-alkyl-6-imino-... 

Alkylthiopurines may also undergo Mannich and Michael addition reactions. Thus 6-methylthiopurine with formaldehyde and I se ve 9-hydroxymethyl-6-methylthiopurine (67JMC104), and dihydrofuranylation of 2-acetamido-6-benzylthiopurine occurs in the presence of toluene-4-sulfonic acid and 2,3-dihydrofuran to give 2-acetamido-6-benzylthio-9-(tetrahydrofur-2-yI)purine (63JMC471). 

Substituted purines may arise in mixtures with 9-substituted derivatives from direct alkylation of purine anions. They are best prepared however by Traube syntheses. Thus formylation of 4,5-diamino-6-benzylthiopyrimidine and ethylation of the formyl derivatives gave a formamidopyrimidine which readily cyclized to 6-benzylthio-7-ethylpurine in the presence of potassium carbonate (B-68MI40901, p. 31). The derivative is clearly a ready source of 7-substituted adenines by reaction with ammonia or amines, or of 7-substituted purines by dethiation with Raney nickel. 7-Methylguanine has also been obtained from 7-methyl-guanosine, sodium borohydride and aniline at pH 4.5 (B-78MI40903, p. 615). 

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