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

摘要

Nitroethylenes bearing either a phenylthio or a phenylselenoether group in beta-position are efficient synthetic equivalents of nitroacethylene. A [4+2] cycloaddition/carbenoid-mediated elimination of PhS(e)CH_3/[4+2] cycloaddition sequence of reactions is shown to produce formal biscycloadducts of nitroacetylene in high yields. The cycloaddition reactions are activated by high-pressure and proceed with high regioselectivities and stereoselectivities.