CYCLIC KETONES, THEIR PREPARATION AND THEIR USE IN THE SYNTHESIS OF AMINO ACIDS

摘要

A method is provided for making an enantiomerically pure compound of the formula: in which R and R' represent C₁-C₁₀ alkyl, C₂-C₁₀ alkenyl or C₃-C₁₀ cycloalkyl and the wedges signify (S)- or (R)-stereochemistry, the substituents in compound (II) being trans. Conjugate addition is carried out between an organometallic nucleophile that provides a group R as defined above and (R)-4-acetoxycyclopent-2-en-1-one, (S)-4-acetoxycyclopent-2-en-1-one or a similar compound in which acetoxy is replaced by another leaving group to give, e.g. in the case of the acetoxy compound, a trans 3,4-disubstituted addition product of formula III or IV;