3742-89-0Relevant articles and documents
(3S, 4R)-3,4-trans-disubstituted azetidin-2-one intermediates
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, (2008/06/13)
The invention relates to an improved process for the preparation of compounds of formula STR1 or salts thereof, starting from compounds of formulae STR2 via compounds of formulae STR3 in which compounds R1 is hydrogen or lower alkyl, R2 is an organic radical which may carry a functional group which may be protected by a customary protective group R2o, R3 is hydrogen or a customary carboxyl protective group R3o, W is a group which can be replaced by a thiocarboxylic acid radical of formula III, and Z is oxygen or sulfur.