The Formation of Silylated β‐Lactams from Silylketenes through Lewis Acid Promoted [2+2] Cycloaddition: A Combined Theoretical and Experimental Study

Abstract

Abstract The stereoselective formation of silylated cis ‐β‐lactams from (trimethylsilyl)ketene and an α‐imino ester by Lewis acid catalysis is described. Theoretical results suggest that the reaction between (trimethylsilyl)ketene and trans ‐(methoxycarbonyl)‐ N ‐methylformaldimine would proceed most favourably with the BF 3 catalyst coordinated to the ketene. Moreover, the calculated energy barriers account for the cis : trans ratio found experimentally. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)