Enantioselective Catalytic Cyclopropanation-Rearrangement Approach to Chiral Spiroketals

Org Lett. 2021 May 21;23(10):3955-3959. doi: 10.1021/acs.orglett.1c01113. Epub 2021 May 6.

Abstract

A highly enantioselective synthesis of chiral heterobicyclic spiroketals is reported via a "one-pot" cyclopropanation-rearrangement (CP-RA) cascade reaction that is sequentially catalyzed by a chiral Rh(II) catalyst and tetrabutylammonium fluoride (TBAF). Exocyclic vinyl substrates form spirocyclopropanes with tert-butyldimethylsilyl-protected enoldiazoacetates in excellent yields and with excellent enantioselectivities when catalyzed by chiral dirhodium(II) carboxylates, and following desilylation with simultaneous rearrangement in the presence of TBAF, they give (S)-spiroketals in high yields with excellent chirality retention (>95% ee).

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.