Visible-Light-Promoted Reduction of Epoxides, Hydroxysulfonates, and Halohydrines with Alkyltitanium Alkoxides.

Alkyltitanium alkoxides generally serve as nucleophiles in reactions with carbonyl compounds and cross-coupling. Their application as reductants is known but remains underdeveloped. Here, we report that irradiation with visible light makes these organometallic compounds efficient reducing agents for the dehalogenation of 1,2- and 1,3-haloalcohols. This reaction was utilized for the reduction of epoxides and sulfonates, which proceeded through a sequence of the in situ halohydrin formation and photochemical dehalogenation. Ester, amide, nitrile, alkyne, and remote bromide groups were stable under the reaction conditions.