Enantioselective Michael Addition/Cyclization/Desymmetrization Sequence of Prochiral Cyclic Hemiacetals and Nitroolefins: Synthesis of Chiral Oxygen-Bridged Bicyclic Compounds

Org Lett. 2022 Dec 23;24(50):9254-9258. doi: 10.1021/acs.orglett.2c03815. Epub 2022 Dec 13.

Abstract

The organocatalytic enantioselective Michael addition of functionalized prochiral cyclic hemiacetals and nitroolefins has been developed under cooperative enamine and hydrogen bond catalysis. The obtained chiral hemiacetal intermediates could be used in the subsequent diastereocontrolled cyclization/desymmetrization divergent process to access (1) 9-oxabicyclo[3.3.1]nonane or 8-oxabicyclo[3.2.1]octane frameworks via oxocarbenium ion-mediated Friedel-Crafts cyclization, and (2) 2,9-dioxabicyclo[3.3.1]nonane frameworks via intramolecular nucleophilic cyclization. Experimental results suggest that there is neighboring group participation controlling the diastereoselectivities of the desymmetrization process.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bridged Bicyclo Compounds* / chemistry
  • Catalysis
  • Cyclization
  • Oxygen*
  • Stereoisomerism

Substances

  • nonane
  • Oxygen
  • Bridged Bicyclo Compounds