Chemical- and light-induced isomerization of the P=C bond of a 1-phosphabutadiene

Canadian Journal of Chemistry, e-First Articles. Treatment of Mes*P=C(Si(CH3)3)Br with CH2=CHMgBr in the presence of Pd(0) affords 1-phosphabutadiene Mes*P=C(Si(CH3)3) –CH=CH2 (1) selectively as the Z isomer. Remarkably, treatment of Z-1 with n-BuLi (0.1 equiv.) resulted in quantitative formation of E-1. The exact role of the n-BuLi is unknown; however, it appears to be required to promote the isomerization in the absence of light. The isomerization of Z-1 to E- 1 was also mediated by sunlight with the reaction mixture consisting of a ca. 1:9 ratio of Z-1 to E-1. DFT calculations were consistent with the thermodynamic favorability of the isomerization of Z-1 to E-1.
Source: Canadian Journal of Chemistry - Category: Chemistry Authors: Source Type: research