1,2-Dimethyleneazulenes, an o-xylylene type reactive intermediate, have been generated by the heating of 1,3-dihydroazuleno[1,2-c]thiophene dioxides. The reactive intermediates were efficiently trapped by dienophiles, such as N-phenylmaleimide and diethyl azodicarboxylate, to form [4+2] cycloaddition products in high yields.
1,2-Dimethyleneazulenes, an o-xylylene type reactive intermediate, have been generated by the heating of 1,3-dihydroazuleno[1,2-c]thiophene dioxides. The reactive intermediates were efficiently trapped by dienophiles, such as N-phenylmaleimide and diethyl azodicarboxylate, to form [4+2] cycloaddition products in high yields.
1,2-Dimethyleneazulenes, an o-xylylene type reactive intermediate, have been generated by the heating of 1,3-dihydroazuleno[1,2-c]thiophene dioxides. The reactive intermediates were efficiently trapped by dienophiles, such as N-phenylmaleimide and diethyl azodicarboxylate, to form [4+2] cycloaddition products in high yields.