Ti/Ni-Mediated Inter- and Intramolecular Conjugate Addition of Aryl and Alkenyl Halides and Triflates

In this work, we show that the unique combination of a nickel catalyst and Cp2TiCl allows the direct conjugate addition of aryl and alkenyl iodides, bromides, and to a lesser extent, chlorides and triflates to α,β-unsaturated carbonyls at room temperature, without requiring the previous formation of an organometallic nucleophile. The reaction proceeds inter- and intramolecularly with good functional group compatibility, which is key for the development of free protecting group methodologies. Carbo- and heterocycles of five- and six-membered rings are obtained in good yields. Moreover, some insights about the mechanism involved have been obtained from cyclic voltammetry, UV–vis, and HRTEM measurements.