ASYMMETRIC CATALYSIS - ASYMMETRIC CATALYTIC INTRAMOLECULAR HYDROSILATION AND HYDROACYLATION

[摘要] Catalysts of the type [Rh(chiral diphosphine)](+) efficiently catalyse the intramolecular hydrosilation of silyl ethers derived from allylic alcohols. The products can be converted to chiral 1,3-diols. High enantiomeric excesses (ee's) are observed for substances bearing an aryl group at the olefin terminus. These same catalysts produce chiral cyclopentanones from 4-substituted 4-pentenals. Tertiary, acyl and ester substituents give nearby quantitative ee's. The mechanism of hydrosilation is inferred to involve silyl olefin insertion, whereas the key step in hydroacylation probably involves reductive elimination of the metallacyclohexanone intermediate.

[发布日期] 1994-04-11