Direct synthesis of aryl-annulated []carbazoles by gold(i)-catalysed cascade reaction of azide-diynes and arenes.

The gold-catalysed annulation of conjugated alkynes bearing an azido group with arenes gave annulated []carbazoles. Using benzene, pyrrole, and indole derivatives as the nucleophiles, benzo[]-, pyrrolo[2,3-]-, and indolo[2,3-]carbazoles were produced, respectively. The reaction proceeded through pyrrole and benzene ring construction accompanied by the formation of two carbon-carbon and one carbon-nitrogen bond and the cleavage of two aromatic C-H bonds.

Total Synthesis of Dictyodendrins by the Gold-Catalyzed Cascade Cyclization of Conjugated Diynes with Pyrroles.

In total and formal syntheses of dictyodendrins B, C, E, and F, the key step involved the direct construction of the pyrrolo[2,3-c]carbazole core by the gold-catalyzed annulation of a conjugated diyne with a pyrrole to form three bonds and two aromatic rings. The subsequent introduction of substituents at the C1 (Suzuki-Miyaura coupling), C2 (addition to an aldehyde), N3 (alkylation), and C5 positions (Ullman coupling) provided divergent access to dictyodendrins.