Thermolysis of 2-methoxy-2,5,5-trimethyl-3-1,3,4-oxadiazoline

The principal product of gas phase thermal decomposition of 2-methoxy-2,5,5-trimethyl-Δ 3 -1,3,4-oxadiazoline (methoxyoxa-diazoline) was found to be 1-methoxy-1-[(1-methylethenyl)oxy]-ethane (vinyl ether). This arises from a selective 1,4-hydrogen shift in the carbonyl ylide intermediate. Fragmentation of the carbonyl ylide is the dominant process in the solution thermolysis of methoxyoxadiazoline. The phase and temperature dependence of this thermolysis is discussed in terms of the probable structure of the carbonyl ylide intermediate.