A Novel Asymmetric Synthesis of Carboxyric Acids Based on the Reaction of Sulfoxides with Ester Enolates

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 with 99% chiral induction from the sulfur chiral center. The adducts were converted to optically active β-substituted carboxylic acid derivatives. In the same way, treatment of optically active 1-chlorovinyl p-tolyl sulfoxides, which were synthesized from symmetrical ketones and (R)-(-)-chloromethyl p-tolyl sulfoxide in three steps, with lithium enolate of carboxylic acid tert-butyl esters gave optically active adducts having a substituent at the α-position with high 1,4-chiral induction from the sulfur chiral center in high yield.

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