Substrate-controlled regioselective hydrophosphorylation of allenes to enable photocatalytic synthesis of alkenylphosphoryl compounds

Abstract

In the realm of allene hydrofunctionalizations, controlling the selectivity of radical additions to allenes has constituted a formidable challenge for many years. Here, we present a sustainable strategy for visible-light-induced hydrophosphorylation of allenes with H-phosphine oxides in green solvents. Under the mild reaction conditions, a diverse range of alkenylphosphoryl compounds are synthesized through a radical pathway in a highly stereoselective and regioselective manner. The regioselectivity can be precisely modulated by altering the substituent patterns on the allene substrates. Mechanistic investigations, including control experiments and fluorescence quenching studies, have elucidated the phosphinoyl radical pathway of the reactions. Computational studies indicate that the catalytic cycle involves sequential reactions, including radical addition, single electron transfer, and proton transfer, with the latter step being identified as the determinant of regioselectivity.