Solid Phase Tin Reagents

Polymer supported tin hydrides ensure complete removal of tin by-products, but their synthesis is not trivial. They have been used for reductions of halides and for ring closures, and the resulting polymer-bound tin halide can be easily filtered from the reaction mixture, regenerated, and reused. 

The trimethyltin fluoride is generated in situ or can be added initially. The advantage of this reagent is that it is less volatile than trimethyltin chloride, not easily absorbed through the skin and can be filtered off at the end of the reaction, rather than distributed in both the organic and aqueous waste streams. 

Drying and reusing the same resin gives a modest 25% conversion, but after regeneration (LiAlH4 and oxidation with Pd(PPhj)4), the recycled resin gives an improved 79% yield. 

ICP-MS analysis of the homoallyl alcohols formed in these reactions indicates negligible tin and cerium contamination. The resin can be recovered and regenerated with allyl bromide and zinc or allylmagnesium bromide and reused several times without notable loss of activity. 

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