Diels-Alder cycloadditions of the N-vinylcarbazole radical cation

The first radical cation Diels-Alder reactions of N-vinylcarbazole, the substrate for which radical cation cycloaddition (cyclodimerization) was first observed more than 30 years ago, have now been observed. The additions of N-vinylcarbazole to both cyclopenta-1,3-diene and cyclohexa-1,3-diene, catalyzed by tris(4-bromophenyl)aminium hexachloroantimonate, have been observed. Further, a two step mechanism for these cycloadditions has been established through the use of stereospecifically labelled substrate ((Z)-N-(2-deuteriovinyl)carbazole).