The formation of phosphepine 1-oxides in the reaction of 1,2-dihydrophosphinine 1-oxoides with dichlorocarbene

The ring expansion of the regioisomeric 1,2-dihydrophosphinine 1-oxides to phosphepine 1-oxides effected by dichlorocarbene addition under solid-liquid PTC conditions is discussed. The dichlorocarbene addition to the 1-methoxy-dihydrophosphinine 1-oxides containing one or two methyl groups on the skeleton gives a phosphabicyclo-octene beside the phosphepine 1-oxide, or a phosphabicyclo-octadiene oxide, respectively