Synthesis of Indanones and Spiroindanones by Diastereoselective Annulation Based on a Hydrogen Autotransfer Strategy.

An unprecedented nickel-catalyzed domino reductive cyclization of alkynes and o-bromoaryl aldehydes is described. The reaction features broad substrate scope and is tolerant of a variety of functional groups, providing straightforward access to biologically significant indanones and spiroindanone pyrrolidine derivatives in good yields with excellent regio- and diastereoselectivity. Preliminary mechanistic studies have shown that indanones are formed by the cyclization of o-bromoaryl aldehydes and alkynes to form indenol intermediates, followed by hydrogen autotransfer.