A new strategy for the construction of polycycles bearing a nitrogen atom on the ring fusion

Nitroethylenes bearing either a phenylthio or a selenoether group in β-position are efficient synthetic equivalents of nitroacetylene. A [4+2] cycloaddition/carbenoid-mediated elimination of PhS(e)CH3/[4+2] cycloaddition sequence of reactions is shown to produce formal biscycloadducts or nitroacetylene in high yields. The cycloaddition reactions are activated by high-pressure and proceed with high regioselectivities and stereoselectivities.