Reactivity of a Sterically Unencumbered α‐Borylated Phosphorus Ylide towards Small Molecules

The influence of substituents on α‐borylated phosphorus ylides (α‐BCPs) has been investigated in a combined experimental and quantum chemical approach. The synthesis and characterization of Me(3)PC(H)B(iBu)(2) (1), consisting of small Me substituents on phosphorous and iBu residues on boron, is reported. Compound 1 is accessible through a novel synthetic approach, which has been further elucidated through DFT studies. The reactivity of 1 towards various small molecules was probed and compared with that of a previously published derivative, Ph(3)PC(Me)BEt(2) (2). Both α‐BCPs react with NH(3) to undergo heterolytic N−H bond cleavage. Different di‐ and trimeric ring structures were observed in the reaction products of 1 with CO and CO(2). With PhNCO and PHNCS, the expected insertion products [Me(3)PC(H)(PhNCO)B(iBu)(2)] and [Me(3)PC(H)(PhNCS)B(iBu)(2)], respectively, were isolated.