Synthesis of γ-Lactones from intermediate 2-(γ-Hydroxyacyl)imidazoles by N-Methylation and Base-catalyzed C-C Bond Cleavage. Application to the Synthesis of (+/-)-Cavernosin

Article abstract of DOI:10.1016/S0040-4020(01)80461-0

Reaction of the allyl anions of O-trialkylsilyl-N-alkyl-2-(1'-hydroxyprop-2'-enyl)imidazoles with aldehydes and ketones gives products of α- and γ-attack.Greater steric hindrance in the anion (triisopropyl vs t-butyldimethylsilyl) and in the aldehyde or ketone favours the γ-products.Sequential desilylation, N-methylation and treatment with base resulted in cleavage of these products to γ-lactones.The method was applied to the synthesis of (+/-)-cavernosine.