Asymmetric Retro-Claisen Reaction Catalyzed by Chiral Aza-Bisoxazoline-Zn(II) Complex: Enantioselective Synthesis of α-Arylated Ketones

Org Lett. 2023 Mar 17;25(10):1706-1710. doi: 10.1021/acs.orglett.3c00372. Epub 2023 Mar 7.

Abstract

An asymmetric retro-Claisen reaction of α-monosubstituted β-diketones and quinones (or quinone imine) has been developed under the catalysis of a chiral aza-bisoxazoline-Zn(II) complex. The reaction proceeds via a sequence of conjugate addition, arylation, hemiketal anion-initiated C-C bond cleavage, and enantioselective protonation of enolate to provide various functionalized α-arylated ketones bearing a tertiary stereogenic center with high enantioselectivities. Notably, biologically important benzofuran and γ-butyrolactone derivatives could be synthesized by application of the developed protocol.