Researches on antiviral agents.5. Lithiation of 6-methyluracil as a new and efficient entry to C(6)-substituted uracils

Synthesis of numerous C(6)-substituted uracils I (R1, R2 = Me, benzyl; R3 = alkyl, phenylthio, pyridinyl, etc.) was achieved by lithiation of N(1),N(3)-substituted 6-methyluracils with LiHMDS, followed by the reaction of the resulting lithio derivs. with carbon, sulfur, and selenium electrophiles. The unexpected migration of the N(1)-benzoyl group in the metalation-alkylation and the high stereoselectivity obtained in the reaction with substituted cyclohexanones are also reported. The pharmacol. activity of I was not reported.