Carboboration of isocyanates with tris(pentafluorophenyl)borane and evidence for dissociative FLP chemistry of an acid–base pair

Abstract

We report on the reactivity of isocyanates towards tris(pentafluorophenyl)borane which was found to result in the 1,2-carboboration of the isocyanate CO bond. The resulting six-membered heterocyclic compounds can be rationalized as adducts of imino-boranes with isocyanates and react accordingly, allowing for the dissociative displacement of the trapped isocyanate moiety in a series of exchange reactions. Related carboelementation reactions with the heavier group 13 analogues, Al(C₆F₅)₃ and Ga(C₆F₅)₃, result in a dimerization of the carboboration products to afford eight-membered heterocycles.