Polymethylhydrosiloxane, when combined with titanium(IV) isopropoxide, provides a convenient system for the conversion of esters to the corresponding primary alcohols in the presence of a wide range of functional groups. Reactions are carried out as mixtures of the neat reaction components; workup with aqueous alkaline THF affords primary alcohols in good to excellent yields. The system tolerates primary alkyl bromides and iodides, olefins, epoxides, and alkynes. Steric differentiation of methyl and tert-butyl esters is also possible. The results observed in the parent and related reactions argue against pathways involving Lewis-acid catalysis and anionic hydridosilicate-mediated reductions, and instead support a neutral titanium hydride complex or strongly associated titanium/silane complex as the active reducing agent.
“An Inexpensive Air-Stable Titanium-Based System for the Conversion of Esters to Primary Alcohols”, J. Org. Chem., 1995, 60(24), 7884-7890.