Carbohydrate-derived allylic stannanes

The preparation of tri(n-butyl)tin derivatives of various carbohydrates is described. Glycal derivatives were converted into the corresponding stannanes upon treatment with Bu₃SnH under photochemical activation. This reaction was found to be regioselective but not stereoselective. Upon treating the glycals with Bu₃Sn(Bu)Cu(CN)Li₂ as a nucleophile, the corresponding stannanes were obtained in an enantiomerically pure form. Preliminary results indicate that these stannanes may be converted into enantiopure C-glycosides by radical substitution of the tributyltin function.