Titanium(III)-Catalyzed Reductive Decyanation of Geminal Dinitriles by a Non-Free-Radical Mechanism

Abstract

A titanium-catalyzed mono-decyanation of geminal dinitriles is reported. The reaction proceeds under mild conditions, tolerates numerous functional groups, and can be applied to quaternary malononitriles. A corresponding desulfonylation is demonstrated as well. Mechanistic experiments support a catalyst-controlled cleavage without the formation of free radicals, which is in sharp contrast to traditional stoichiometric radical decyanations. The involvement of two Ti^III species in the C-C cleavage is proposed, and the beneficial role of added ZnCl₂ and 2,4,6-collidine hydrochloride is investigated.

Keywords: C−C activation; catalysis; cyanides; electron transfer; titanium.