N‐Heterocyclic Carbene Catalyzed CC Bond Cleavage in Redox Esterifications of Chiral Formylcyclopropanes

Abstract

A clean break: An N-heterocyclic carbene catalyzes the ring-opening of chiral non-racemic formylcyclopropanes, with simultaneous oxidation of the aldehyde function and without the need for stoichiometric reagents. The activated carboxylate intermediate is trapped by a variety of nucleophiles, thus leading to chiral esters, thioesters, or carboxylic acids (see scheme; DBU=1,8-diazabicyclo[5.4.0]undec-7-ene, EWG=electron- withdrawing group, Nu=nucleophile.)