A novel 4‐methylene‐3‐borahomoadamantane: 1,1‐organoboration of an alkyn‐1‐ylsilane using 1‐boraadamantane

Abstract

1,1-Dibromo-2,2-bis(trimethylsilylethynyl)ethene (2) reacts with two equivalents of 1-boraadamantane (1) by 1,1-organoboration of both trimethylsilylethynyl groups to give a triene 3 bearing two 4-methylene-3-borahomoadamantane moieties in terminal positions. The triene was characterized by one-and two-dimensional 1 H, 11 B, 13 C and 29 Si NMR spectroscopy in solution and X-ray structural analysis in the solid state. The planes of the C C double bond are strongly twisted against each other as a result of the bulky substituents, and the surroundings of the boron atoms deviate from the ideal trigonal planar geometry owing to the tension in the tricyclic frameworks.