Catalyst-Controlled [3 + 2] and [4 + 2] Annulations of Oximes with Propargyl Alcohols: Divergent Access to Indenamines and Isoquinolines

Rhodium(III)- and iridium(III)-catalyzed C-H activation of oximes and coupling with propargyl alcohols is discussed. Depending on the catalyst, the reaction pathway switched between [3 + 2] and [4 + 2] annulations, thus giving divergent access to indenamines and isoquinolines in a one-pot and atom-economical manner. The hydroxyl group in the tertiary propargyl alcohol substrate was found to be crucial in controlling chemoselectivity. Five-membered rhodacycle and iridacycle intermediates have also been identified for mechanism hypotheses.