Thermolysis of a 2-methoxy-Δ3-1, 3, 4-oxadiazoline involves loss of N2 with formation of a carbonyl ylide. The fate of the carbonyl ylide depends on its environment and on the other substituents present. Thus, the ylides from 2-methoxy-2, 5, 5-trimethyl-Δ3-1, 3, 4- oxadiazoline (1) and from 2-methoxy-2-(4-methoxyphenyl)-5, 5-dimethyl-Δ3-1, 3, 4- oxadiazoline (2) are trapped very efficiently by methanol. However, the ylide from 1 is ...
