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.