Cycloaddition behavior of 3,4-diazacyclopentadienone dioxides toward bicyclo[2.2.1]heptadiene derivatives. X-ray analysis of the cycloadduct and reaction pathway

Article abstract of DOI:10.1002/jhet.5570300618

The cycloaddition behavior of 2,5-disubstituted 3,4- diazacyclopentadienone dioxide 1a-c toward epoxynaphthalene (2a) and norbornadiene (2b) was investigated. The structures of the products were determined on the basis of the ¹H- and ¹³C-nmr spectral data and the X- ray analysis data. The stereospecific formation of the endo-exo 1,3-dipolar cycloadducts from 2a indicates that the cycloadduct resulted from the direct 1,3-dipolar cycloaddition. The cycloaddition behavior of 1 toward 2 is discussed on the basis of the PM3-calculated transition-state structures.