Catalyst-Controlled Regioselective Acylation of β-Ketoesters with α-Diazo Ketones Induced by Visible Light.

A catalyst-controlled acylation reaction of β-ketoesters was developed for the first time by combining visible-light photoactivation with Lewis acid or base catalysis. By employing a NiCl2·glyme complex with a bis(oxazoline) ligand as the Lewis acid catalyst, C-acylation products are exclusively achieved, while utilizing pyridine or DABCO as the Lewis base catalyst affords O-acylation products with complete regioselectivity. A range of β-ketoesters with satisfactory structural diversity were suitable for this transformation, demonstrating the functional group compatibility of the method, which was attributed to the mild reaction conditions. This success is heavily built upon the visible-light-induced Wolff rearrangement and the unique catalytic activation modes, and thus, this work significantly expands the applications of ketene chemistry.