Boron Lewis acid-catalyzed formal insertion of isocyanides into a C-O bond of benzyl esters

Transition-metal catalyzed isocyanide insertions are one of the key elemental steps for a variety of isocyanide-based transformations. However, the formal insertions catalyzed by main group catalysts are still in their infancy. Herein, the atom-economical synthesis of imides was achieved using a boron Lewis acid catalyzed cascade process consisting of a rare isocyanide insertion with benzyl esters and the Mumm rearrangement. It was found that slow addition of isocyanides is effective for avoiding the deactivation of the boron catalyst.