Synthesis of Canthin-4-ones and Isocanthin-4-ones via B Ring Construction
Maria Koyioni1, Andreas Kourtellaris1, Panayiotis A Koutentis1
1Department of Chemistry, University of Cyprus, P.O. Box 20537, 1678 Nicosia, Cyprus.
Abstract:
Canthin-4-one is synthesized via a six-step procedure starting from commercially available 3-amino-4-bromopyridine in 26% overall yield. 3-Amino-4-bromopyridine is initially converted to 8-bromo-1,5-naphthyridin-4(1H)-one. O-Methylation, intermolecular Pd-catalyzed C-C coupling, and demethylation afford the key intermediate, 8-(2-chlorophenyl)-1,5-naphthyridin-4(1H)-one, for which intramolecular C-N coupling completes the synthesis of the canthin-4-one skeleton. Ten canthin-4-one analogues were prepared in addition to the parent compound. With minor modifications, the synthesis also applies to the synthesis of two series of isocanthin-4-ones.
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