Synthesis of 3-1-(t-Butyldimethylsilyloxy)ethyl-4-carboxymethyl-2-azetidinone Derivatives

摘要

Isoxazolidine derivatives 7 and 8 were synthesized from N-benzyl-C-(2-benzyloxyethyl)nitrones by 1,3-dipolar cycloaddition with ethyl crotonate. The isoxazolidine derivatives were converted to モ -amino acid esters 9a and 9b by reduction with zinc in acetic acid. The モ-amino acid esters were reacted with methylmagnesium bromide to give the 2-azetidinones (13a, 13b). The benzyl group of 2-azetidinones were removed by Birch reduction. The products were oxidized with PDC to give 3-1-(t-butyldimethylsilyloxy)ethyl-4-carboxymeth yl-2-azetidinone derivatives (2a, 2c).