Radicals from fragmentation of benzyloxymethoxycarbenes in solution

2-Benzyloxy-2-methoxy-5,5-dimethyl-Delta(3)-1,3,4-oxadiazolines, including the parent as well as p-substituted analogues, undergo thermolysis at 100%C in benzene to afford a mixture of products. Two primary fragmentations of the oxadiazolines were identified. The major pathway involves 1,3-dipolar c ycloreversion to N-2 and the corresponding carbonyl ylides. The latter diss ociate to acetone and the corresponding benzyloxy(methoxy)carbenes, which u ndergo fragmentation to ArCH2 and MeOCO radical pairs that recombine to aff ord methyl arylacetates. Carbene dimers were not observed, showing that the fragmentation process is faster than carbene dimerization. A second fragme ntation pathway observed for the oxadiazolines is an alternative cyclorever sion to the corresponding benzyl methyl carbonate and 2-diazopropane. Produ cts from diazopropane included acetone azine and, in some instances, traces of propene.