Synthesis of Highly Substituted Cyclopropanes via the Quasi-Favorskii Rearrangement of α,α-Dichlorocyclobutanols

Org Lett. 2020 Aug 7;22(15):5715-5720. doi: 10.1021/acs.orglett.0c01229. Epub 2020 Apr 24.

Abstract

A method for the synthesis of highly substituted cyclopropanes via a quasi-Favorskii rearrangement is described. The method includes the combination two chemical transformations starting from α,α-dichlorocyclobutanones prepared via the [2 + 2] Staudinger ketene cycloaddition between either terminal- or cis-olefins and dichloroketene. First, α,α-dichlorocyclobutanones are reacted with organocerium reagents to afford the corresponding tertiary alcohols in good to excellent yields through a nucleophilic addition reaction that provided exclusively anti-products. Second, upon irreversible deprotonation, the tertiary α,α-dichlorocyclobutanols underwent a ring-contraction reaction (i.e., quasi-Favorskii rearrangement) to form structurally diverse cyclopropanes in moderate to good yields. The syn-stereoselectivity during the quasi-Favorskii rearrangement was evaluated using DFT analysis.

Publication types

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

MeSH terms

  • Biochemical Phenomena
  • Cycloaddition Reaction
  • Cyclopropanes / chemical synthesis*
  • Cyclopropanes / chemistry
  • Ethylenes / chemistry*
  • Ketones / chemistry*
  • Molecular Structure
  • Stereoisomerism

Substances

  • Cyclopropanes
  • Ethylenes
  • Ketones
  • ketene