Closed-loop hydrostannylation of white phosphorus using Bu3SnCl and NaBH4: one-pot access to organophosphorus compounds.

The direct functionalization of white phosphorus (P4) is gaining attention as an alternative to state-of-the-art multi-step processes. The hydrostannylation of P4 affords valuable monophosphorus compounds directly via a hydrostannylphosphine mixture (Bu3Sn)xPH3-x (where x = 0-3) that reacts with suitable electrophiles. However, previous reports required terminal reductants which are infeasible for industrial-scale applications. Here, we report an improvement in this chemistry using NaBH4 as the terminal reducing agent, generating the key hydrostannylation agent Bu3SnH in situ from Bu3SnCl. The resulting (Bu3Sn)xPH3-x mixtures were successfully functionalized towards useful P1 compounds. Furthermore, we present the 'one-pot' preparation of tetrakis(hydroxymethyl)phosphonium chloride (THPC), the subsequent direct recycling of Bu3SnCl, and preliminary attempts towards the catalytic synthesis of THPC.