A New Three-Component Reaction to Yield 3-Spirocyclopropanated beta-Lactams

A one-pot three-component reaction for the direct conversion of certain alkylhydroxylamine hydrochlorides 8 (alkyl = benzyl, p-methoxybenzyl, benzhydryl, tert-butyl), formaldehyde (9) or an alkyl glyoxylate (10) and bicyclopropylidene (2) to furnish 3-spirocyclopropanated 2-azetidinones 7, 11 has been developed. Microwave heating of mixtures of the three components in the presence of sodium acetate in ethanol for 15–120 min furnished the products 7, 11 in 49–78% yield (7 examples). A new protocol for the oxidative deprotection of the 3-spirocyclopropanated methyl 1-(p-methoxybenzyl)-2- carboxylate 11b-Me provides the β-lactam building block 17- Me in 90% yield, and the latter can be reprotected and activated with an N-tert-butoxycarbonyl (Boc) group in 82% yield.