Au^III-Catalyzed Highly Efficient Synthesis of a-Ylidene-b-Diketones

Shaozhong Wang, Liming Zhang*

Department of Chemistry/216, University of Nevada, Reno, 1664 North Virginia Street, Reno, Nevada 89557

We report here a Au^III-catalyzed, highly efficient synthesis of a-alkylidene or benzylidene-b-diketones from propargylic esters. With mostly 1-5 mol % of dichloro(pyridine-2-carboxylato)gold(III), various a-ylidene-b-diketones can be prepared in close to quantitative yields. An additional feature of this method is the observed high to excellent stereoselectivities in the cases of dienyl b-diketones. A plausible methanism is proposed involving novel intramolecular acyl migration to nucleophilic Au^III-C(sp²), and the stereoselectivity is explained.