Photoreduction of aromatic carbonyl compounds by tetra-n-butyltin and tri-n-butyltin hydride

Abstract

By a comparison of the bimolecular rate constants for the abstraction of hydrogen by triplet-state benzophenone from tetra-n-butyltin and tri-n-butyltin hydride, it has been established that the high reactivity of the hydride is due to the weak tin–hydrogen bond. A number of other carbonyl compounds, including αβ-unsaturated ketones are photoreduced to alcohols by the hydride. The tetra-substituted 1,2-glycols formed from certain ketones (e.g. 2-acetylnaphthalene) were found to undergo photoinduced cleavage to give α-hydroxyarylmethyl radicals which abstracted hydrogen from the hydride to give secondary alcohols. The photoreaction of benzaldehyde with the hydride gave polymeric material instead of benzyl alcohol.