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Concise syntheses of 9-methoxyellipticine, 3,4-dihydroellipticine (µ-alkaloid D), 1,2,3,4-tetrahydroellipticine, 2-methyl-1,2,3,4-tetrahydroellipticine, olivacine, 3,4-dihydroolivacine, (±)-guatambuine, and (±)-janetine were developed starting from hexatriene intermediates readily obtained by Pd-catalyzed tandem cyclization/cross-coupling reaction of indolylborates. The route enables the facile construction of pyrido[4,3- b]carbazoles by Cu-catalyzed 6π-electrocyclization and subsequent transformation of the pyridocarbazole intermediates into pyrido[4,3- b]carbazole alkaloids. [ABSTRACT FROM AUTHOR]

A concise synthesis of pyrano[3,2‐e]indole alkaloid fontanesine B by a Fischer indolization is described. This key Fischer indolization starts with the pyran‐ring and alkene intact, facilitating potential synthetic applications. Furthermore, fontanesine B and its isomer were evaluated for in vitro antiproliferative activity against human colorectal cancer cells. The isomer of fontanesine B showed higher antiproliferative activity than the natural product, fontanesine B (2). [ABSTRACT FROM AUTHOR]

Cu-catalyzed 6π-electrocyclization of triene-substrates of type (I) provides a facile access to pyrido[4,3-b]carbazoles, which represent advanced intermediates for the construction of various ellipticine and olivacine alkaloids. [ABSTRACT FROM AUTHOR]

Cu(I)-mediated dimerization of skatoles (I) provides indoloquinazolinones (II). [ABSTRACT FROM AUTHOR]

The alkaloid tryptanthrin (IIa) is further converted into the natural products phaitanthrin A (IXa), phaitanthrin B (IXb), and cruciferane (X). [ABSTRACT FROM AUTHOR]