A diene-transmissive Diels–Alder reaction involving inverse electron-demand hetero-Diels–Alder cycloaddition of cross-conjugated azatrienes

The initial inverse electron-demand hetero-Diels–Alder reaction of N-sulfonyldivinylmethanimine with electron-rich dienophiles (ethyl vinyl ether and ethyl vinyl sulfide) affords [4+2] cycloadducts with high endo selectivity. The monocycloadducts then undergo a second Diels–Alder reaction on the newly formed diene unit with electron-deficient dienophiles (tetracyanoethylene, 4-phenyl-1,2,4-triazoline-3,5-dione, and N-phenylmaleimide) to give highly stereoselectively the crossed biscycloadducts, hexa- and octahydroquinolines, and octahydropyridopyridazines.