FREMGANGSMAADE TIL FREMSTILLING AF (3S)-3,4-TRANS-DISUBSTITUEREDE AZETIDINONER

摘要

The present invention relates to an improved process for the manufacture of (3S)-3,4-trans-disubstituted azetidinones of the formula (I) in which R1 represents hydrogen or lower alkyl, R2 represents hydrogen or a hydroxy-protecting group, Y represents the group -S(=O)-R3 or -S(=O)2-R3 wherein R3 represents an organic radical bonded to the sulphur atom by a carbon atom that is not bonded to hydrogen, or the group -C(=O)-O-R3' wherein R3' represents an organic radical bonded to the oxygen atom of the carboxy group by a carbon atom that is not bonded to hydrogen, or a carboxy-protecting group, and R4 represents hydrogen or an amino-protecting group R4'. The process according to the invention is carried out under particularly forvorable reacton conditions and yields compounds (I) in particularly high yields.