Hydrogen-Borrowing and Interrupted-Hydrogen-Borrowing Reactions of Ketones and Methanol Catalyzed by Iridium

Reported herein is the use of catalytic [{Ir(cod)Cl}2] to facilitate hydrogen‐borrowing reactions of ketone enolates with methanol at 65 °C. An oxygen atmosphere accelerates the process, and when combined with the use of a bulky monodentate phosphine ligand, interrupts the catalytic cycle by preventing enone reduction. Subsequent addition of pro‐nucleophiles to the reaction mixture allowed a one‐pot methylenation/conjugate addition protocol to be developed, which greatly expands the range of products that can be made by this methodology. On loan: [{Ir(cod)Cl}2] facilitates hydrogen‐borrowing reactions of ketone enolates with methanol at 65 °C as described. Performing the reaction under an oxygen atmosphere aids the process, and when combined with a bulky monodentate phosphine ligand, interrupts the catalytic cycle by preventing enone reduction. The addition of pro‐nucleophiles to the reaction mixture completes a one‐pot methylenation/conjugate addition method.