Arylideneamines (1) added to the acyl isocyanato moiety of methacryloy
l isocyanate (MAI) to produce the corresponding [4 + 2] cycloadducts,
2H-1,3,5-oxadiazin-4(3H)-ones (2). It has been clarified that even at
low temperature the cycloadducts (2) partially dissociate to two origi
nal substrates, MAI and 1, in solution on the basis of VT-nmr spectros
copy.