Rhodium-Catalyzed Annulation Reactions of 2-Cyanophenylboronic Acid with Alkynes and Strained Alkenes

reaction: see text. A new 3 + 2 annulation reaction was developed in which 2-cyanophenylboronic acid reacted as a three-carbon component with alkynes or alkenes to afford substituted indenones or indanones. The use of an alkynoate even produced benzotropone, a formal 3 + 2 + 2 adduct. The cyclic skeletons were constructed by intramolecular nucleophilic addition of an intermediate organorhodium(I) species to a cyano group.