Regioselective synthesis of bis(silyl enol ethers) and bis(conjugated enones) through electron transfer from Mg metal

Treatment of α,β-unsaturated ketones with Mg metal in the presence of trimethylsilyl choride (TMSCl) brought about facile and regioselective reductive dimerization to give the corresponding bis(silyl enol ethers), 1,6-bis(trimethylsilyloxy)-1,5-dienes. Similar Mg-promoted reductive dimerization of 1,3-cyclic diketones in the presence of TMSCl followed by acid-catalyzed hydrolysis led to selective formation of the corresponding 1,6-diketo-2,4-dienes in moderate to good yields.