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. A nickel‐catalyzed domino reductive cyclization of alkynes and o‐bromoaryl aldehydes provided straightforward access to biologically significant indanones and spiroindanone pyrrolidine derivatives (see scheme). The reaction was found to be tolerant of a variety of functional groups and proceeded in good yields with excellent regio‐ and diastereoselectivity.