Diels–Alder Reactions of 2‐Vinylindoles with Open‐Chain C=C Dienophiles

Abstract The synthesis of diastereoisomeric 3,4‐disubstituted 1,2,3,4‐tetrahydrocarbazoles by Diels–Alder cycloaddition reactions between [( E )‐2‐vinyl]indole‐1‐carboxylic acid ethyl esters and open‐chain C=C dienophiles is reported and discussed. The reactions proceed with high regioselectivity whereas the diastereoselectivity ranges from moderate to excellent depending on the substitution pattern on both the dienes and dienophiles and on the catalyst employed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)