Asymmetric synthesis of tetrahydrofurans by diastereoselective [3+2] cycloaddition of allylsilanes with α-keto esters bearing an optically active cyclitol as a chiral auxiliary
Tin (IV) chloride mediated [3+2] cycloadditions of allylsilanes with optically active α-keto esters derived from L-quebrachitol afforded tetrahydrofuranderivatives via 1,2-silyl migration with high level of diastereoselectivity. Removal of the chiral auxiliary gave silyl-substituted tetrahydrofurans of excellent opticalpurity.