Silicon acceleration of a tandem alkene isomerization/electrocyclic ring-opening of 2-methyleneoxetanes to α,ß-unsaturated methylketones.

ABSTRACT

The first rearrangement of 2-methyleneoxetanes to α,ß-unsaturated methylketones is reported. It is proposed that when these substrates are heated, the corresponding oxetenes are formed and subsequently undergo electrocyclic ring-opening to methyl vinylketones. In particular, α-silyl-α,ß-unsaturated methylketones were isolated in moderate to high yields and with high stereoselectivities. Based on the proposed mechanism, density functional theory explains the differential kinetics and stereoselectivities among substrates.