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Sequential Diels−Alder Reaction of in Situ Generated 2,3-Dimethylenepyrrole and Carbodienophiles:  Rapid Synthesis of 2,3,6,7-Tetrasubstituted Carbazoles

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journal contribution
posted on 17.12.1999, 00:00 by Jeffrey T. Vessels, Slawomir Z. Janicki, Peter A. Petillo
2,3,6,7-Tetrasubstituted-1,2,3,4,5,6,7,8-octahydrocarbazoles 2 were synthesized in 46−90% yields by sequential Diels−Alder reactions from N-benzyl-2,5-dimethyl-3,4-bisacetoxymethylpyrrole (1) and dienophiles such as maleic anhydride, maleimides, ethyl maleate, fumaronitrile, and ethyl acrylate. The 2,3,6,7-tetrasubstituted carbazoles 3 were then synthesized in 32−87% yields from 2 by oxidation with DDQ.