Photoredox α-Alkylation of Phosphonates by Styrenes

A new protocol for photocatalyzed regioselective α-alkylation of alkyl phosphonates with styrenes without the use of transition metals has been developed. The monoalkylation reaction occurs in 10 min using 0.1 mol % of the 4DPAFIPN photocatalyst. Conditions for the double addition of styrenes to phosphonates have also been found, enabling the regioselective addition of two different styrenes to a phosphonate. This method provides high yields and good tolerance of functional groups. This protocol has also been successfully applied on a gram scale.