Reaction of 1,3‐Dialkyl‐4,5‐dimethylimidazol‐2‐ylidenes with 2‐Bromo‐2,3‐dihydro‐1<i>H</i>‐1,3,2‐diazaboroles (Alkyl=<i>i</i>Pr and <i>t</i>Bu)

Abstract

Abstract 2‐Bromo‐2,3‐dihydro‐1 H ‐1,3,2‐diazaboroles ( 3a – c ) were synthesized by cyclocondensation of dilithiated 1,4‐diazabutadienes ( 5a – c ) with boron tribromide in hexane. 3a was also obtained by sodium amalgam reduction was conducted in ether solvents, diboroxane ( 2 ) resulted as the main product. Compound 3a and 1,3‐dialkyl‐4,5‐dimethylimidazol2‐ylidenes ( 6a, b ) underwent halide displacement to afford the borolylimidazolium salts 7a, b . Compounds 2, 3a – c , and 7a, b were characterized by elemental analyses and spectroscopic methods ( 1 H, 11 B, 13 C NMR; Ir; MS). The molecular structures of 2 and 7a were established by single‐crystal X‐ray diffraction analyses.