Chiral‐at‐Ruthenium Catalyst with Sterically Demanding Furo[3,2‐b]pyridine Ligands

Abstract

A sterically demanding derivative of a previously introduced chiral‐at‐metal ruthenium(II) catalyst scaffold is introduced. It is composed of two bidentate furo[3,2‐b]pyridyl functionalized N‐heterocyclic carbene ligands. Their cis‐coordination generates helical chirality and a stereogenic ruthenium center. Two additional labile acetonitriles compose the catalytic site which is highly shielded by two 2‐(tert‐butyl)furo[3,2‐b]pyridine moieties. The synthesis of the non‐racemic ruthenium catalyst and its catalytic properties for the enantioselective alkynylation of 2,2,2‐trifluoroacetophenone and pentafluorobenzaldehyde are reported and compared with sterically less demanding derivatives.