DIASTEREOSELECTIVE CONJUGATE ADDITION TO (-CAMPHORSULFONIC ACID-DERIVED NITROALKENES - SYNTHESIS OF ALPHA-HYDROXY AND ALPHA-AMINO-ACIDS())

Diastereoselective tandem conjugate addition of both oxygen- and nitro gen-centered nucleophiles to the novel (1S)-10-camphorsulfonic acid de rived nitroalkenes 9, 10, and 11 and ozonolysis gave the alpha-hydroxy and alpha-amino thiol acid derivatives 12, 13, and 14. In all cases, the (R)-diastereomer was formed as the major component albeit with onl y modest levels of selectivity (33-71% de). The structures of the prod ucts and the stereochemistry of the Michael addition step were unequiv ocally established by X-ray crystallographic studies of nitroalkenes 9 and 10 and (2S)-12c and (2R)-13a and by alternative syntheses from (S )-alanine, (S)-valine, and ethyl (S)-lactate.