2-Azetidinone: Die Reaktion von α-Silylcarbanionen mit Mesoxalsäurediethylester

2-Azetidinones: The Reaction of Diethyl Ketomalonate with α-Silylcarbanions 1,4-Diaryl-2-azetidinones 1 are base-catalysed silylated at ?78°C, forming 2 . The title reaction, starting with the anion of 2 , results in the formation of the dimeric products 4 . The structure of 4 is elucidated by X-ray analysis. In the presence of chlorotrimethylsilane, the α-silylcarbanion of 2 reacts with diethyl ketomalonate 3 to form 3-methylene-2-azetidinones 8 resp. 11 .