Lewis and Brønsted basicity of phosphine-diazomethane derivatives

Abstract

The compounds EtOC(O)CHNNPR₃ (R = Ph 1, Cy 2, tBu 3) were prepared via the reactions of the diazomethane and a phosphine. In subsequent reactions with B(C₆F₅)₃, the compounds 2 and 3 are shown to exhibit Lewis basicity at the carbonyl oxygen affording EtOC(O(B(C₆F₅)₃))CHNNPR₃ (R = Cy 5, tBu 6). Reactions of 5 and 6 with water or phenol illustrated the Brønsted basicity at the nitrogen atom adjacent phosphorus, affording the compounds, [EtOC(O)CHNNHPR₃][HOB(C₆F₅)₃] (R = Cy 7, tBu 8) and [EtOC(O)CHNNHPR₃][PhOB(C₆F₅)₃] (R = Cy 9, tBu 10), respectively. The formulation of these products is confirmed via spectroscopic and crystallographic studies, and insight is garnered from computations.