Remote electronic effect on the N-heterocyclic carbene-catalyzed asymmetric intramolecular Stetter reaction and structural revision of products.

The remote electronic effects of chiral N-heterocyclic carbene catalysts on the asymmetric intramolecular Stetter reaction are investigated. The reaction rate and enantioselectivity were markedly influenced by a substituent at a remote position of the catalyst. The absolute configurations of the products are revised on the basis of X-ray diffraction. Density-functional theory calculations rationalize the improvement of the enantioselectivity using an electron-deficient catalyst.