Synthesis of B-trisubstituted borazines via the rhodium-catalyzed hydroboration of alkenes with N, N′, N″-trimethyl or N, N′, N″-triethylborazine

Abstract

Hydroboration of terminal and internal alkenes with N, N′, N″-trimethyl- and N, N′, N″-triethylborazine was carried out at 50 °C in the presence of a rhodium(I) catalyst. Addition of dppb or DPEphos (1 equiv.) to RhH(CO)(PPh 3) 3 gave the best catalyst for hydroboration of ethylene at 50 °C, resulting in a quantitative yield of B, B′, B″-triethyl- N, N′, N″-trimethylborazine. On the other hand, a complex prepared from ( t-Bu) 3P (4 equiv.) and [Rh(coe) 2Cl] 2 gave the best yield for hydroboration of terminal or internal alkenes.