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Synfacts 2006(1): 0027-0027
DOI: 10.1055/s-2005-921697
DOI: 10.1055/s-2005-921697
Synthesis of Heterocycles
© Georg Thieme Verlag Stuttgart · New York
A Versatile Synthesis of Benzacanthinones by Intramolecular Radical Coupling
J. H. Markgraf*, A. A. Dowst, L. A. Hensley, C. E. Jakobsche, C. J. Kaltner, P. J. Webb, P. W. Zimmerman
Williams College, Williamstown, USA
Further Information
Publication History
Publication Date:
16 December 2005 (online)
Significance
The synthesis of the naturally occurring benzocanthinone (1) and its analogues using a radical-induced oxidative cyclization for D ring formation is described. The facile construction of the precursor N-benzoyl (and pyridoyl) β-carbolines by Bischler-Napieralski reaction allows the preparation of several benzacanthinone analogues. The best results were obtained with halogen substituents (Br > Cl, I) in the pyridinyl ring (path a). In case of path b, a mixture of regioisomers resulting from cyclization into both rings A (14% yield) and C was obtained.