Synthesis of Triarylmethanes via Palladium-Catalyzed Suzuki Coupling of Trimethylammonium Salts and Arylboronic Acids

Abstract

An efficient palladium-catalyzed Suzuki coupling of 1,1-diarylmethyl-trimethylammonium triflates with arylboronic acids is reported. This reaction offers a novel approach to triarylmethane derivatives in good to excellent yields with the palladium-catalyzed C-N bond cleavage as the key feature. Broad substrate scope regarding both reaction partners are observed. Moreover, reactive functional groups such as vinyl and formyl groups are conserved in this transformation.

Recent Advances in the Pd‐Catalyzed Coupling of Arylhydrazines and Ammonium Salts via C−N Bond Cleavage

“…[40] In 2018, our group also reported a more chanllenging Suzuki coupling for the synthesis of triarylmethanes using 1,1diarylmethyl-trimethylammonium triflates as coupling partners (Scheme 26). [41] Triarylmethanes with a variety of different functional groups such as OMe, Cl, CHO, and CN were obtained in high yields. Soon after, Liu and co-workers achieved a similar coupling reaction using an N-heterocyclic carbene-palladium(II) catalyst (Scheme 27).…”

Direct synthesis of completely unsymmetrical triarylmethanes via Fe(III) salt‐mediated in situ o‐quinone methides process

“…reaction in the presence of an acid catalyst, but poor regioselectivities were often obtained (Scheme 1a). [13][14][15][16][17][18][19][20][21][22][23][24] In recent years, a number of novel methods such as crosscoupling reactions [25][26][27][28][29][30] and C-H functionalization [31][32][33][34] have been developed. However, most of the reactions require expensive transition metals and ligands (Scheme 1b).…”

“…[ 10–12 ] The conventional method for the synthesis of unsymmetrical triarylmethanes is the Friedel–Crafts reaction in the presence of an acid catalyst, but poor regioselectivities were often obtained (Scheme 1a). [ 13–24 ] In recent years, a number of novel methods such as cross‐coupling reactions [ 25–30 ] and C–H functionalization [ 31–34 ] have been developed. However, most of the reactions require expensive transition metals and ligands (Scheme 1b).…”

Palladium-Catalyzed Hiyama Coupling of Benzylic Ammonium Salts via C–N Bond Cleavage

“…Since the pioneering work by Sarandeses, many efforts have been made in this field by the groups of Wang, MacMillan, Watson, and Tortosa, among others . In this context, our group is interested in the palladium-catalyzed cross-coupling reaction via the cleavage of the C–N bond, and we have reported the palladium-catalyzed Suzuki cross-coupling of benzyltrimeth-ylammonium salts for the synthesis of diarylmethane and triarylmethane derivatives . Based on our previous successes, we envisioned that arylsilanes could also be used as coupling partners to react with benzylic ammonium salts to construct the C­(sp 2 )–C­(sp 3 ) bond.…”

“…26 In this context, our group is interested in the palladium-catalyzed cross-coupling reaction via the cleavage of the C−N bond, 27 and we have reported the palladium-catalyzed Suzuki cross-coupling of benzyltrimeth-ylammonium salts for the synthesis of diarylmethane 28 and triarylmethane derivatives. 29 Based on our previous successes, we envisioned that arylsilanes could also be used as coupling partners to react with benzylic ammonium salts to construct the C(sp 2 )−C(sp 3 ) bond. In such context, we herein report the first palladium-catalyzed Hiyama crosscoupling of benzyltrimethylammonium salts for the construction of diarylmethane derivatives.…”