Photocatalyzed Formal All-Carbon [3+2] Cycloaddition of Aromatic Aldehydes with Arylethynyl Silanes.

Herein, we report a photoinduced TBADT-catalyzed formal all-carbon [3+2] cycloaddition of aromatic aldehydes and arylethynyl silanes, which combines acyl C-H and ortho C-H activation of aromatic aldehydes, offering a new method for constructing the indanone scaffold under mild conditions. By choosing an appropriate silane as the precursor, one can selectively retain or remove the α-silyl group of the indanone products during the reaction. Preliminary mechanistic studies point to a reaction mechanism involving a 1,5-H shift as a key step.