Synthesis of indanones by sequential Heck-reduction–cyclization–alkylation (HRCA) reactions

A simple and efficient synthesis of indanones, bearing a quaternary carbon centre, has been developed. The method features, in a one-pot process, the use of a multi-task palladium catalyst for the sequential Heck-reduction reactions, followed by a base-mediated cyclization–alkylation sequence. This methodology, called Heck-reduction–cyclization–alkylation (HRCA), is carried out under mild and simple experimental conditions with the use of inexpensive reagents. The mild conditions have been made possible by the use of diazonium salts that allow Heck couplings at moderate temperature (40 °C) under ligand-free conditions.