Borane-induced radical reduction of 1-alkenyl- and 1-alkynyl-λ-iodanes with tetrahydrofuran

Exposure of 1-alkenyl(phenyl)- and 1-alkynyl(phenyl)-λ³-iodanes to THF at room temperature in the presence of a catalytic amount of trialkylborane results in smooth reduction to give 1-iodo-1-alkenes and 1-iodo-1-alkynes as major products, respectively. The key step in the reductions probably involves a single-electron transfer from α-tetrahydrofuryl radical to the λ³-iodanes, which generates the labile 9-I-2] iodanyl radicals.