A New Mild Method for the C-Acylation of Ketone Enolates. A Convenient Synthesis of β-Keto-Esters, -Thionoesters, and -Thioesters
作者:Karl J. Hale、Milosz Grabski、Jakub T. Flasz
DOI:10.1021/ol303324a
日期:2013.1.18
A new method for ketone enolate C-acylation is described which utilizes alkyl pentafluorophenylcarbonates, thiocarbonates, and thionocarbonates as the reactive acylating agents, and MgBr2·Et2O, DMAP, and i-Pr2NEt as the reagents for enolization. A wide range of ketones have been observed to undergo clean C-acylation via this protocol.
A catalyst-controlled acylationreaction 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