Asymmetric syn‐Selective Michael Addition of Enolates to Chiral 8‐Phenylmenthyloxy Vinyl Chromium Carbene Complexes

Michael addition reactions of ketone and ester lithium enolates to optically active Fischer vinylcarbene complexes derived from (‐)‐8‐phenylmenthol take place with high syn selectivity and high levels of asymmetric induction. The initial Michael adducts can be further elaborated through diastereoselective addition of organometallic reagents to ketones and aldol reactions. Removal of the metal fragment and chiral auxiliary group leads to cyclic enol ethers with three or five contiguous stereogenic centers and of high enantiomeric purity.