A new halogen-exchange reaction between Sn-F and Li-X: Selective 1,2- and 1,4-reductions of α,β-unsaturated ketones and effects of halogen substituents on the regioselectivity of organotin hydrides

Article abstract of DOI:10.1246/bcsj.72.465

We have found that halogen-exchange occurs effectively between Sn-F and Li-X (X = I, Br, Cl) in tin hydride reagents. This fact induced a complete change in the regiochemistry in the reductions of α,β-unsaturated ketones 1 with Bu₂SnH₂-Bu₂SnF₂ (Reagent A): the use of Reagent A in combination with HMPA performed 1,2-reductions, while the addition of LiI to Reagent A achieved 1,4-reductions. It was demonstrated that the regioselectivity of organotin hydrides greatly depends on the properties of the halogen substituents attached to tin atoms.