N-Heterocyclic Carbene-Catalyzed Enantioselective [3 + 2] Annulation of Enals with Vinyl Ketones

J Org Chem. 2023 Jan 20;88(2):1219-1226. doi: 10.1021/acs.joc.2c01894. Epub 2023 Jan 9.

Abstract

An unprecedented N-heterocyclic carbene (NHC)-catalyzed enantioselective [3 + 2] annulation of enals with vinyl ketones has been achieved. Unlike chalcones, the β-unsubstituted enones, namely, vinyl ketones, have remained challenging in terms of reactivity, especially enantioselectivity. The disubstituted cyclopentenes were obtained in good yields and excellent stereoselectivities in the presence of Ti(OiPr)4.