Palladium‐Catalyzed Regioselective C4 Functionalization of Indoles with Quinones

Abstract

A synthetic strategy for the installation of diversely functionalized quinones at the C4 position of indoles is developed via palladium-catalyzed CÀ H and double CÀ H functionalization. This synthetic protocol provides a rapid route to a variety of 4-quinonylindoles via the direct coupling of 3-formylindoles with quinones. Furthermore, this synthetic methodology also efficiently affords biologically interesting bis(indol-4yl)quinones in good yields by direct one-pot double CÀ H activation of 3-formylindoles with the corresponding quinones.

A Synthetic Route to Tetrahydro-1H-azepino[4,3,2-cd]indoles via Ring-Opening Cyclization of Activated Azetidines with 4-Bromoindole: Toward a Vasopressin V2 Receptor Antagonist

“…Alkaloids with 3,4-fused indole tricyclic moieties including 6-, 7-, 8-, 9-, and 12-ring sizes having various carbon, nitrogen, and oxygen linkages are found in nature and exhibit high biological activities. Many attempts have been made to synthesize them. − Functionalization at the 4-position of indole is a difficult task under the normal electrophilic reaction, as 3-, 5-, or 7-positions are preferred for this purpose. , Among indole derivatives, azepinoindole-based alkaloids and other related natural products possess azepinoindoles as the core structures in many drug molecules ,, and show remarkable antifungal, antibacterial, antimicrobial, anti -HIV, antimalarial activities along with some metabolic activity against hypertension and act as a receptor antagonist . In the past few decades, azepinoindoles attracted synthetic organic and medicinal chemists because of their wide applicability, such as (+)- syn -clavicipitic acid, , (−)- anti -clavicipitic acid, , (−)-aurantioclavine, vasopressin V2 receptor antagonist, etc.…”