Cyclizaticn of 3-formyl-2-acetylenylindole oximes

Rapid Access to Amino-Substituted Quinoline, (Di)Benzofuran, and Carbazole Heterocycles through an Aminobenzannulation Reaction

“…Yellow solid, 96%; mp 113−114 °C (lit. 120−121 °C); 1 H NMR (300 MHz, CDCl 3 , δ) 10.33 (s, 1H), 8.40 (d, J = 7.2 Hz, 1H), 7.71−7.68 (m, 2H), 7.53−7.34 (m, 6H), 3.91 (s, 3H).…”

Synthesis of β- and γ-Carbolines by the Palladium/Copper-Catalyzed Coupling and Cyclization of Terminal Acetylenes

“…The thermal reaction of 1-benzenesulfonyl-3-(trimethylsilylethynyl)indole-2-carboxaldehyde with NH 3 also afforded the corresponding desilylated β - carboline in a low yield (37%). See ref a for details.…”

“…Hibino and Sakamoto have separately reported that substituted β - carbolines and their N -oxides can be synthesized readily by heating the corresponding 3-(1-alkynyl)indole-2-carboxaldehydes with NH 3 5a or NH 2 OH. 5b,c The β - carboline N -oxides obtained by this method have been further elaborated by Hibino in the total synthesis of naturally occurring β - carboline alkaloids pyridindolols. 5b,c Recently, Rossi has improved Sakamoto's carboline synthesis to the synthesis of 1,3-disubstituted β - carbolines by employing 2-acyl-3-(1-alkynyl)indoles and NH 3 5d. Similarly, γ-carbolines and their N -oxides have also been synthesized by heating the corresponding 2-(1-alkynyl)indole-3-carboxaldehydes with NH 3 or NH 2 OH. 5a,g The reduction of γ-carboline N -oxides by PCl 3 readily affords the corresponding γ-carbolines in satisfactory yields 5g…”

“…Our interest in the synthesis of carbolines prompted us to examine the synthesis of a variety of 3-substituted β - and γ-carboline derivatives. Our goal during this work was to provide a clean, high-yielding, and general synthesis of functionalized β - and γ-carbolines, which would provide a useful alternative to Sakamoto's carboline synthesis 5a.…”

Synthesis of Annulated γ-Carbolines and Heteropolycycles by the Palladium-Catalyzed Intramolecular Annulation of Alkynes

“…Pyrido[4,3- b ]-5 H -indoles, commonly known as γ -carbolines, which are condensed analogues of the ellipticine/olivacine anticancer agents, have been studied extensively because of their potential pharmaceutical importance . However, there are relatively few synthetic studies of γ -carboline derivatives having wide scope and generality, , and the synthesis of new alkaloid derivatives of γ -carboline with an additional ring fused across the 4- and 5-positions is rare . Two closely related examples of this type of heteropolycyclic system having interesting biological activity are the pentacyclic γ -carboline 1 , which is a cardiovascular agent, and the indolonaphthyridone 2 , which acts as a conformationally restricted 5-HT 3 receptor antagonist …”