For the first time, we have synthesized a silsesquioxane substituted Sn compound 1 and studied its catalytic properties. As in Sn-Beta zeolite, which has recently received significant attention due to its ability to catalyze various important organic transformations in aqueous media, in this molecule the rigid nature of the substituents enforces the tetrahedral substitution with two coordination vacancies on the Sn atom. This together with a remarkable e-withdrawing tendency of the silsesquioxane ligand enhances the Lewis acidity of 1. Accessibility of the Sn center was probed by the addition of various Lewis bases, and both single and syn dual bindings relevant to catalysis were found possible. In our preliminary studies, capabilities of 1 as a Lewis acid catalyst were demonstrated in an alcoholysis reaction of styrene oxide, in which only the CH-substitution was observed in an epoxide ring opening reaction. Catalyst 1 also acts as a hydride shift reagent in a Meerwein–Ponndorf–Verley reaction between benzyl alcohol and p-nitrobenzaldehyde.

Tetrahedral oxo-Sn catalyst

249th National Meeting (2015)

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