Reactivity of 2-Silyl- and 2-Stannyl-Substituted Phosphirenes

Two methodologies have been tested for the functionalization of phosphirenes. In the first one, the C−Si bond of a 2-silylphosphirene is activated by a substoichiometric quantity of fluoride ion (TBAF) in THF at −78 °C. Using this technique, it is possible to perform a protodesilylation or a functionalization by benzaldehyde. However, at room temperature with a stoichiometry of fluoride, a nucleophilic attack takes place at P, leading to a ring-opened fluorophosphine. Stille cross-coupling with a 2-stannylphosphirene in the presence of [PdL2] as a catalyst leads to an alkynylphosphine by [1,3] migration of tin from C to P.