Enantiocontrolled synthesis of trialkyl-substituted stereogenic carbons. A general route to cis-3,5-dialkyl gamma-lactones
[reaction: see text] Lewis acid treatment of tertiary Co2(CO)6-propargylic alcohols having a stereochemically defined benzyloxy group at the gamma-benzyl position yielded after cobalt demetalation sec-dialkyl bishomopropargylic alcohols in good yields. The reaction is highly stereoselective and predictable, providing pure stereoisomers. The use of benzyl-alpha,alpha'-d2 ethers permitted the stereoselective d-labeling of methines and methylenes. Very simple chemical manipulations provided a general methodology to obtain the enantiomers of 3,5-dialkyl-gamma-lactones.
Diaz
D
Instituto Universitario de Bio-Organica Antonio Gonzalez, Universidad de La Laguna, Tenerife, Spain.
Martin
VS