Decarboxylative Cross‐Coupling of Aryl Tosylates with Aromatic Carboxylate Salts

Abstract

Scheme 1. Cu/Pd-catalyzed decarboxylative cross-coupling. M = Ag, Cu; R = (hetero)aryl, vinyl, acyl; R' = (hetero)aryl; X = I, Br, Cl, OTf. Tf = trifluoromethanesulfonyl.

Bimetallic Catalysis using Transition and Group 11 Metals: An Emerging Tool for CC Coupling and Other Reactions

“…[77] Subsequently, the catalysis underwent continuous improvement, such as microwave heating, [78] the use of aryl tosylates instead of aryl triflates, [79] or the introduction of silver decarboxylation at only 120 8C, which is more than 50 8C lower than the best copper catalysts known. [80] The percentages of Pd and Cu or Ag used were also reduced to the range 2 % Pd and 5 % Cu or Ag, much lower figures than in the initial studies.…”

Low‐Temperature Ag/Pd‐Catalyzed Decarboxylative Cross‐Coupling of Aryl Triflates with Aromatic Carboxylate Salts

“…The use of sterically demanding ligands such as PA C H T U N G T R E N N U N G (o-Tol) 3 had an adverse effect on the decarboxylation step (Table 1, entries 6-11). Among the silver sources tested, silver carbonate gave the best results, but other silver salts may be used as well (Table 1, entries [12][13][14]. The reaction works best in aprotic solvents such as Nmethylpyrrolidone (NMP) or dimethylacetamide (DMAc).…”

“…[12] In addition, we were able to show that decarboxylative cross-couplings can be performed using aryl electrophiles with non-coordinating leaving groups such as triflates [13] or tosylates. [14] We reasoned that the low affinity of these ions to silver(I) might enable the crucial salt metathesis between silver sulfonate salts a and potassium carboxylates 1 (Scheme 1). This prompted us to embark on the search for a new, low-temperature protocol for the decarboxylative cross-coupling of aryl sulfonates with potassium carboxylates using a Ag/Pd catalyst system.…”

Decarboxylative Cross‐Coupling of Mesylates Catalyzed by Copper/Palladium Systems with Customized Imidazolyl Phosphine Ligands

“…In this variant, the decarboxylation step is mediated by a Cu I [9] or Ag I [10] catalyst, while a Pd complex catalyzes the coupling with the carbon electrophile. Whereas aryl bromides and iodides can be converted with very simple ligand systems, [11] the activation of aryl chlorides, [12] triflates, [13] and tosylates [14] requires the use of sophisticated catalyst systems containing electron-rich, bulky phosphine ligands. However, all attempts to develop decarboxylative couplings of the notoriously hard-to-activate methanesulfonates (mesylates) have failed so far (Scheme 1).Aryl and alkenyl mesylates are particularly attractive carbon electrophiles for preparative-and industrial-scale syntheses, since they have the lowest molecular weight of all sulfonate leaving groups.…”