Preparation of Hetero‐π‐Conjugated Compounds by Double Nucleophilic Addition to Haloalkynes and C−H Cyclization

Abstract

AbstractWhen a mixture containing 1‐halo‐1‐alkyne, a dinucleophilic agent, and a base (Cs2CO3 or K3PO4) was heated in DMF, regio‐ and stereo‐selective nucleophilic addition of the dinucleophilic agent to the acetylenes occurred. This reaction yielded (Z,Z)‐bis(haloalkene), which subsequently underwent Pd‐catalyzed cyclization through C−H bond activation, resulting in the formation of two‐oxygen‐ or ‐nitrogen‐containing hetero‐π‐conjugated compounds. N‐(5‐Hydroxynaphthalen‐1‐yl)methanesulfonamide was treated with 2‐phenyl‐1‐chloroethyne followed by 1‐chloro‐1‐hexadecyne. After these reactions, Pd‐catalyzed double C−H cyclization was employed to produce 1H‐2‐phenyl‐7‐tetradecylbenzofuro[7,6‐g]indole. Notably, this compound transformed into a fan‐shaped structure at 86 °C and transitioned into a smectic A phase characterized by a layered structure.