Hydrosilylation of Esters via a Titanocene(III) Borohydride–PMHS System: Scope, Limitations, and Mechanistic Insights

The hydrosilylation of aromatic and aliphatic esters using catalytic amounts of titanocene-(III) borohydride and poly-(methylhydrosiloxane) (PMHS) as the terminal reductant is described. Alcohol yields range from 43% to 99%, with select esters requiring the addition of isopropanol to promote reactivity. This modification is proposed to facilitate in situ formation of a more reactive titanocene-(III) hydride species, which appears necessary for efficient ester reduction. This ester reduction protocol is mild, cost-effective, operationally simple and has potential utility in broader reductive transformations.