DIASTEREOSELECTIVE SYNTHESIS OF ALPHA-BROMO AMIDES LEADING TO DIASTEREOMERICALLY ENRICHED ALPHA-AMINO, ALPHA-HYDROXY AND ALPHA-THIOCARBOXYLIC ACID-DERIVATIVES

alpha-Bromo amides derived from Oppolzer's camphorsultam can be prepared diastereoselectively starting from racemic alpha-bromo acids, and undergo epimerisation under appropriate conditions leading to an enhanced d.e.. By reacting the individual isomers or the mixture of diastereoisomers with a suitable nucleophile it is possible to obtain alpha-substituted carboxylic acids, including alpha-amino- alpha-hydroxy- and alpha-thiocarboxylic acid derivatives, in diastereomerically enriched form.