Boron Lewis Acid Catalyzed Hydrophosphorylation of N-Hetero- aryl-Substituted Alkenes

The hydrophosphorylation of N-heteroaryl-substituted alkenes catalyzed by a boron Lewis acid catalyst is reported. This reaction occurs with a range of alkenes bearing N-heterocycles, including pyridines, a quinoline, a pyrrole, and a benzothiazole, resulting in the production of 13-N-heteroaryl alkylphosphonates in good yields under additive-free, operationally simple conditions. The mechanistic insights suggest that this hydrophosphorylation involves the deprotonation of the P-H bond of dialkyl phosphites, enabled by the cooperative effects of a boron acid and the basic N-heterocyclic moiety of the alkenes. The resulting phosphonate anion serves as an effective phosphorus nucleophile for the conjugate addition to the concurrently formed N-protonat-ed alkenes. These 13-N-heteroaryl alkylphosphonates can be further converted into other valuable organophosphorus compounds through the introduction of an alcohol group or the reduction of the phosphine oxide moiety.