Photocatalytic Asymmetric Acyl Radical Truce–Smiles Rearrangement for the Synthesis of Enantioenriched α-Aryl Amides

By Wei-Yang Ma
Matteo Leone
Etienne Derat
Pascal Retailleau
Chada Raji Reddy
Luc Neuville
Géraldine Masson

The radical Truce–Smiles rearrangement is a straightforward strategy for incorporating aryl groups into organic molecules for which asymmetric processes remains rare. By employing a readily available and non-expensive chiral auxiliary, we developed a highly efficient asymmetric photocatalytic acyl and alkyl radical Truce–Smiles rearrangement of α-substituted acrylamides using tetrabutylammonium decatungstate (TBADT) as a hydrogen atom–transfer photocatalyst , along with aldehydes or C-H containing precursors. The rearranged products exhibited excellent diastereoselectivities (7:1 to >98:2 d.r.) and chiral auxiliary was easily removed. Mechanistic studies allowed understanding the transformation in which density functional theory (DFT) calculations provided insights into the stereochemistry-determining step.