Denitrogenative palladium-catalyzed coupling of aryl halides with arylhydrazines under mild conditions

Abstract

The development of a method for the Pd(ii)-catalyzed denitrogenative coupling of arylhydrazines to give functionalized biaryls in good yield, using aryl bromides or aryl iodides as convenient and inexpensive aryl sources, is reported. High functional group tolerance is demonstrated for electronically distinct arylhydrazines as well as aryl halides. The desired products were isolated in good to excellent yields for 58 examples. Control experiments and mechanism studies revealed that the transformation undergoes a base-promoted Pd-catalyzed process.

Synthesis, Characterization and Theoretical Investigation on Thiazoline‐Derived Palladium‐Complexes‐Catalyzed Denitrogenative Cross‐Coupling of Aryl Halides with Arylhydrazines

“…The substrate scope was further extended to the use of aryl chlorides (Table , entries 14–19). Aryl chlorides with electron withdrawing substituents took short time (2 h) to complete the reaction while those with electron donating groups took longer reaction time of 20 h. The catalyst 4 displayed excellent catalytic activity with the turn over frequency of 49.5 h −1 which is four times higher than that of other reported catalyst (TOF=14.0 h −1 ) . To further establish the efficacy of the catalyst 4 , a gram‐scale reaction between 4‐chlorobenzonitrile and phenylhydrazine was performed under the standardized reaction condition (Scheme ) and found that yield of the reaction is excellent (92%).…”

“…Zhao and co‐workers reported an efficient procedure to access bi‐aryls via C aryl ‐N aryl bond cleavage of arylhydrazines with aryl boronic acids under aerobic condition in moderate to good yield . Bi‐aryls were obtained in good yields from Pd‐catalyzed cross‐coupling between arylhydrazines and aryl halides with high functional group tolerance ability were reported by Feng and co‐workers . Though palladium‐catalyzed coupling reactions via C aryl ‐N aryl bond cleavage was reported, the coupling of aryl hydrazine with aryl halides are still in its early stages.…”

Desulfinative palladium‐catalyzed cross‐coupling of arylsulfonyl hydrazides with aryl bromides under air

“…A putative reaction mechanism was then proposed in Scheme . In the first stage, oxidative addition of aryl bromide with Pd (0) into the C‐Br bond formed intermediate A .…”

“…Recently, aryl−aryl bond formation via C−S bond cleavage has attracted considerable attention, and versatile activated C−S bond‐containing partners, such as aryl sulfonyl reagents, have been explored in cross‐coupling reactions under transition metal catalysis. Commercial aryl sulfonyl halides, sulfinates and hydrazines are recognized as the new aryl sources that have been universally utilized in desulfinative arylation reactions recently (Scheme ) …”

“…Recently, aryl−aryl bond formation via C−S bond cleavage has attracted considerable attention, and versatile activated C−S bond-containing partners, such as aryl sulfonyl reagents, have been explored in cross-coupling reactions under transition metal catalysis. Commercial aryl sulfonyl halides, [5,[34][35][36] sulfinates [37][38][39][40][41][42] and hydrazines [42][43][44][45][46][47][48][49][50][51] are recognized as the new aryl sources that have been universally utilized in desulfinative arylation reactions recently (Scheme 1). [52][53][54] As we all known, arylsulfonyl hydrazides are relatively stable, simple to handle and easy to prepare from their corresponding sulfonyl chlorides.…”