High pressure and thermal Diels-Alder reactions of 5-nitro[2.2]paracyclophanepyran-6-one

The Diels-Alder reactions of 5-nitro[2.2]paracyclophanepyran-6-one with 1,3-butadienes and 1,2-dihydro-3-vinyl-naphthalene were examined under thermal and high-pressure conditions. The cycloadditions with 1,3-butadienes occurred in good yield and anti-exo diastereoselectively only under high-pressure conditions; the one with 1,2-dihydro-3-vinyl-naphthalene afforded comparable yields of mixtures of anti/syn adducts under normal and high-pressure conditions. A structural analysis of the reaction products by 1H and 13C NMR spectroscopy is presented.