DIELS-ALDER REACTIONS OF (1H-INDOL-3-YL)-ENACETAMIDES AND (1H-INDOL-3-YL)-ENDIACETAMIDES - A SELECTIVE ACCESS TO ACETYLAMINO-FUNCTIONALIZED [B]ANNELATED INDOLES AND CARBAZOLES

Diels-Alder reactions of the (1H-indol-3-yl)-enacetamides and -endiacetamides 1a-d with some carbodienophiles and 4-phenyl-3H-1,2,4-triazole-3,5(4H)-dione give rise to the novel amino-functionalized carbazoles 4-6 and 8 (Scheme 3). Ethenetetracarbonitrile reacts with 1b to furnish the Michael-type adduct 7 (Scheme 3). Structural aspects of the starting materials 1, which exhibit above all 3-vinyl-1H-indole reactivity, are discussed with regard to the prediction of a Diels-Alder process.