(1)
Pindur, U.; Rogge, M. New [4 + 2] Cycloadditions of in Situ Generated Indolyl Enol Ethers and Their Anions With Dimethyl Acetylenedicarboxylate: A One-Pot Access to 4-Alkoxy-Substituted Carbazoles. Chimia 1992, 46, 441.