Optically active ketones as chiral auxiliaries in the [2,3]-Wittig rearrangement
摘要:
The stereochemical aspects of the [2,3]-Wittig rearrangement of optically active tertiary allyl ethers derived from (+)-camphor and (-)-fenchone were investigated. The rearrangement of the (+)-camphor derivative yielded two olefin products in a 70/30 E/Z ratio. The geometry of the trisubstituted olefin produced during the rearrangement was assigned by NOE experiments. The configuration of the newly formed carbinol center of the products was established by kinetic resolution, Mosher's method, and conversion to derivatives of known absolute configuration. The absolute configuration of the carbinol center for the Z isomer was assigned to be S and that of the E isomer to be R. The (-)-fenchone derivative gave only a single Z olefin product, which was assigned the S configuration at the carbinol center.
Trifunctional Chiral Synthons via Stereocontrolled Yeast Reduction. Preparation of Chiral Pentane-1,3,5-triol Derivatives
作者:Masahiro Hirama、Takeshi Nakamine、Shô Itô
DOI:10.1246/cl.1986.1381
日期:1986.8.5
Easy access to pentane-1,3,5-triol derivatives of highopticalpurity, trifunctional chiral synthons of fundamental importance in the synthesis of various natural products is described, as well as the stereocontrol of baker’s yeastreduction of 5-substituted 3-oxopentanoates.