A carbon–carbon bond formation reaction at the C-4 position of a β-lactam

Abstract

Upon treatment with various organolithiums, 4-acetoxyazetidin-2-one (10) afforded the corresponding carbondisplaced compounds (11), (12), and (13). 4-(3-Diazo-3-ethoxycarbonyl-2-oxopropyl)azetidin-2-one (15) was also synthesised from (10) and ethyl α-diazoacetoacetate in the presence of lithium hexamethyldisilazide in one step. The diazo-compound (15) was thermally cyclised to the bicyclic keto-ester (17) in the presence of rhodium acetate.