N-Arylation of amines, amides, imides and sulfonamides with arylboroxines catalyzed by simple copper salt/EtOH system

Abstract

The coupling of arylboroxines with a variety of amines, amides, imides and sulfonamides catalyzed by a copper salt/EtOH system has been developed. In the absence of a base or additive the corresponding N-arylation products were obtained in moderate to excellent yields.

Copper-Promoted Carbon-Heteroatom Bond Cross-Coupling with Boronic Acids and Derivatives

“…The N-arylation of amines, amides, imides, and sulfonamides with arylboroxines 118 were also developed using copper(II) triflate as the catalyst (10-20 mol%) in ethanol in the absence of base or additive (Scheme 44). 80 The corresponding N-arylation products were obtained in moderate to excellent yield. The use of copper(II) triflate gave further examples: higher yield (98%) and shorter reaction time (6 h) than did the use of copper(II) acetate (48 h, 86% yield).…”

Mechanistic Development and Recent Applications of the Chan–Lam Amination

“…117 An example of boroxine-based amination from Yu and co-workers used catalytic Cu(OTf) 2 in the absence of ligand/base and allowed effective N-arylation of amines and NH-heterocycles (Scheme 8). 150 Despite the reaction being performed in EtOH, no competing etherification was reported. In fact, protic solvents were found to be key for successful cross-coupling with the more common Chan−Lam solvents (PhMe, MeCN, CH 2 Cl 2 ) entirely ineffective.…”

“…The direct use of arylboroxines have seen limited development within Chan-Lam couplings in general.Although it should be noted that where reaction mixtures are dry (as is common for Chan-Lam chemistry in order to avoid phenol formation) then it is highly likely that boroxine is formed in situ from the parent boronic acid. 117 An example of boroxine-based amination from Yu and coworkers used catalytic Cu(OTf)2 in the absence of ligand/base and allowed effective N-arylation of amines and NH-heterocycles (Scheme 8) 150.…”

A quick Chan–Lam C–N and C–S cross coupling at room temperature in the presence of square pyramidal [Cu(DMAP)4I]I as a catalyst

“…1 In 1998, a mild protocol for Cu-mediated oxidative amination of aryl boronic acid was developed independently by Chan,Evans and Lam. 2 Thereafter, a number of modifications have been made to improve the yield and efficiency of Chan-Lam reaction using different copper salts in the presence of various ligands, which include important examples such as Cu(OAc) 2 , 3 CuCl, 4 Cu(OTf) 2 , 5 CuF 2 , 6 and the Cu-b-Cyclodextrin complex. 7 Besides these examples on Chan-Lam coupling reaction, there are also other reports in the literature for C-N and C-S bond formation reactions in the presence of various metals such as Cu, 8 Pd, 9 Ni, 10 and Fe.…”