Cf. Gurtler et al., FORMATION OF PYRIDO[1,2A]INDOLES BY ELECTRON-TRANSFER CATALYZED DIELS-ALDER REACTION BETWEEN 2-VINYLINDOLES AND BETA-ENAMIDOESTERS, Synlett, (2), 1994, pp. 141-142
The formation of the pyrido[1,2a]indole structure (benzopyrrocolin str
ucture) by photo- or electrochemically induced radical cation Diels-Al
der reaction between acceptor substituted 2-vinylindoles and beta-enam
idoesters is reported.