Decarboxylative Cross-Coupling Enabled by Fe and Ni Metallaphotoredox Catalysis
Reem Nsouli, Sneha Nayak, Venkadesh Balakrishnan, Jung-Ying Lin, Benjamin K. Chi, Hannah G. Ford, Andrew V. Tran, Ilia A. Guzei, John Bacsa, Nicholas R. Armada, Fedor Zenov, Daniel J. Weix, Laura K. G. Ackerman
Abstract
High Resolution Image Download MS PowerPoint Slide Decarboxylative cross-coupling of carboxylic acids and aryl halides has become a key transformation in organic synthesis to form C(sp 2 )–C(sp 3 ) bonds. In this report, a base metal pairing between Fe and Ni has been developed with complementary reactivity to the well-established Ir and Ni metallaphotoredox reactions. Utilizing an inexpensive FeCl 3 cocatalyst along with a pyridine carboxamidine Ni catalyst, a range of aryl iodides can be preferentially coupled to carboxylic acids over boronic acid esters, triflates, chlorides, and even bromides in high yields. Additionally, carboxylic acid derivatives containing heterocycles, N -protected amino acids, and protic functionality can be coupled in 23–96% yield with a range of sterically hindered, electron-rich, and electron-deficient aryl iodides. Preliminary catalytic and stoichiometric reactions support a mechanism in which Fe is responsible for the activation of carboxylic acid upon irradiation with light and a Ni I alkyl intermediate is responsible for activation of the aryl iodide coupling partner followed by reductive elimination to generate product.