Diastereoseiective Protonation of Chiral Enolate with Chiral Imides

Article abstract of DOI:10.1055/s-1997-937

Described herein is a diastereoselective protonation of a chiral enolate with chiral imides. When the lithium enolate of (-)-menthone was protonated by (S,S)-imide 1 or (R)-imide 9, cis-ketone 7 was the major product formed (trans-pmduct 6:cis-product 7 = 26:74 ～ 19:81). In contrast, a high trans-selectivity (6:7 = 93:7 ～ 97:3) was obtained for the reaction with (R,R)-imide 8 or (S)-imide 10. The catalytic process of this diastereoselective protonation has been realized using a catalytic amount of these chiral imides and stoichiometric amount of an achiral proton source.