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Diels‐alder reactions of methyl‐ and π‐acceptor‐substituted 2‐vinylindoles with dimethyl acetylenedicarboxylate and tetracyanoethylene: Novel functionalized carbazoles
Author(s) -
Pindur Ulf,
Eitel Manfred
Publication year - 1991
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570280419
Subject(s) - tetracyanoethylene , dimethyl acetylenedicarboxylate , chemistry , dehydrogenation , acceptor , medicinal chemistry , diels–alder reaction , organic chemistry , photochemistry , catalysis , cycloaddition , physics , condensed matter physics
The Diels‐Alder reactions of the 2‐vinylindoles 1a‐1d , which are now readily accessible, with dimethyl acetylenedicarboxylate and tetracyanoethylene give rise to the novel 1,2‐dihydro‐ and 1,2,3,4‐tetrahydrocarbazoles 2, 4 , and 5 as well as the fully aromatized carbazoles 3 . With regard to the product spectrum, the mechanistic rationale comprises a Diels‐Alder step, formal 1,3‐hydrogen shift, ene reaction, and dehydrogenation. Conformational aspects of the 1,2‐dihydrocarbazoles 2b and 2c are also discussed.