Annular ketone, those manufacturing and those uses in synthesizing the amino acid

摘要

A method is provided for making an enantiomerically pure compound of the formula: in which R and R' represent CSUB1/SUB-CSUB10 /SUBalkyl, CSUB2/SUB-CSUB10 /SUBalkenyl or CSUB3/SUB-CSUB10 /SUBcycloalkyl 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;