Asymmetric synthesis of both enantiomers of esters and γ-lactones from optically active 1-chlorovinyl p-tolyl sulfoxides and lithium ester enolates with the formation of a tertiary or a quaternary carbon stereogenic center at the β-position

Abstract

Treatment of optically active 1-chlorovinyl p-tolyl sulfoxides having two different substituents at the 2-position, which were synthesized from aldehydes or unsymmetrical ketones and ( R)-(−)-chloromethyl p-tolyl sulfoxide in two or three steps, with the lithium enolate of tert-butyl acetate gave optically active adducts in 99% chiral induction from the sulfur stereogenic center. The adducts were converted to optically active esters, carboxylic acids, and γ-lactones, which have a tertiary or a quaternary carbon stereogenic center at the β-position. A synthesis of optically active spiro-lactones was realized starting from 2-cyclohexenone by this method.