The room temperature radical addition of sodium hypophosphite to terminal alkynes produces the previously unknown 1-alkyl-1,1-bis-H-phosphinates in moderate yield. The reaction is initiated by R 3 B and air and proceeds under mild conditions in an open container. The bis-sodium salts precipitate spontaneously from the reaction mixtures, thus providing a simple purification procedure and the opportunity for multigram synthesis. The 1,1-bis-H-phosphinate products are novel precursors of the biologically important 1,1-bisphosphonates. We recently reported a novel and general approach towards H-phosphinate derivatives, based on the room temperature radical addition of hypophosphorous compounds to alkenes (Equation 1). 1 Since then, we have studied the reactions of alkynes with sodium hypophosphite under similar conditions and discovered the formation of a new class of compounds: 1-alkyl-1,1-bis-H-phosphinates. 2 We now report the results of this study. The thermal, peroxide-initiated radical reaction of hypophosphorous acid with alkynes has been studied by Nifant'ev and coworkers. 3 Several products were identified depending on the conditions employed (Equation 2). A mixture of trans-and cis-alkenyl-H-phosphinic acids were produced as the major components, along with minor amounts of disubstituted 1,2-bis-H-phosphinic acids. Nifant'ev had also investigated alkenes under the same conditions. 4 Previously, we found that our milder reaction conditions considerably expanded the scope of H-phosphinates which could be produced both in terms of functional group tolerance on the alkene, and hypophosphorous reagent employed. 1 These differences prompted the study of alkynes as substrates under our R 3 B/air and room temperature conditions. As a model study, the reaction of sodium hypophosphite with 1-hexyne was investigated using Et 3 B/air to promote radical formation. The results are summarized in Table 1. Methanol was initially selected as solvent, since sodium hypophosphite has no significant solubility in other common organic solvents at room temperature. Interestingly, the novel 1,1-bis-H-phosphinate was always obtained as the major product (the remaining filtrate contains some unreacted