Palladium-Catalyzed Tandem C–C Activation/Cyclization Induced by Carbopalladation of Functionalized Nitriles: Synthesis of Benzo Dipyrromethenes

Abstract

A palladium-catalyzed carbon–carbon bond activation-initiated reaction of 2-(3-phenyloxiran-2-yl)­benzonitriles with arylboronic acids is reported. Multiple chemical bonds were cleavaged and reconstructed via β-carbon elimination in this reaction, enabling the construction of valuable benzo-fused dipyrromethenes that are difficult to prepare by other methods. Additionally, a series of benzannulated boron dipyrromethenes are synthesized and show practical significance in terms of expanding the applications and types of fluorescent materials. The proposed mechanism is supported by preliminary mechanistic experiments.

Palladium-Catalyzed Three-Component Cascade Reaction of Nitriles: Synthesis of 2-Arylquinoline-4-carboxylates

“…On the basis of these experimental observations and our previous studies, − a plausible reaction mechanism is proposed for the cascade sequences in Scheme . Initially, the arylpalladium species A is generated from transmetalation of arylboronic acid to Pd­(II) catalyst.…”

“…In the past few years, our group has been running ongoing researches targeted on N -heterocycles development from easily available nitriles by transition-metal catalyzed. A series of N -heterocycles have been constructed by our strategies. − However, the synthesis of 2-arylquinoline-4-carboxylate still remains unsolved. Herein, we report the Pd­(II)-catalyzed three-component addition/ring expansion/esterification reaction of 2-(2-oxoindolin-3-yl)­acetonitrile, arylboronic acids, and alcohols, which can serve as a new strategy for one-pot assembly of 2-arylquinoline-4-carboxylates (Scheme e).…”

Metal-catalyzed reactions of organic nitriles and boronic acids to access diverse functionality

“…85 h , i In this regard, in 2020, a Pd( ii )-catalyzed C–C activation-initiated reaction of 2-(3-phenyloxiran-2-yl)-benzonitriles ( 124 ) with arylboronic acids has been developed by Chen and Shao's group for the synthesis of benzo-fused dipyrromethene derivatives ( 125 ) (Scheme 62). 86 The transformation involves the cleavage and reconstruction of multiple chemical bonds via β-carbon elimination for the synthesis of benzo-fused dipyrromethenes. Arylboronic acids with bulky substituents provide better yields as compared with less bulky substituents, suggesting a positive steric influence on the reaction.…”

Aromatic Ring-Fused Dipyrrins: Programmed [4 + 2]-Cycloaddition Pathway with Regio-selectivity upon Alkylamino-Substitution

“…At present, syntheses of aromatic ring-fused dipyrrins primarily depend on special pyrroles (exclusively electro-deficient ring-fused pyrroles) , or the recently developed Pd-catalyzed cyclization reactions (Figure ). Considering the infant stage of the synthetic chemistry of aromatic ring-fused dipyrrins, efficient and concise pathways are still being pursued. The unique sulfolenopyrrole features a sulfolene unit fused at β,β-positions, − and can undergo the cheletropic reaction to extrude SO 2 under heating.…”