Palladium-catalysed direct arylation of heteroarenes using 1-(bromophenyl)-1,2,3-triazoles as aryl source

Abstract

A variety of 1-aryl-1,2,3-triazoles containing heteroarenes at C2-, C3-or C4-positions on the aryl ring was successfully prepared via palladium-catalysed direct arylation. These couplings were performed employing 1 mol% of phosphine-free Pd(OAc) 2 catalyst with 1-(bromophenyl)-1,2,3-triazoles and heteroarenes as coupling partners. A wide variety of heteroarenes such as thiazoles, thiophenes, furans, pyrroles or isoxazoles was tolerated.

Transition Metal‐Mediated Functionalization of Isoxazoles: A Review

“…A wide variety of heteroarenes such as thiazoles, thiophenes, furans, pyrroles and isoxazoles were tolerated. [21] Syntheses of fluorinated molecules has received ever increasing attention due to their wide application in medicinal chemistry, materials, and agrochemicals. [22,23] In 2016, Browne and co-workers investigated the direct C4-arylation of 3trifluoromethylisoxazoles with aryl bromides with PdCl 2 (Scheme 16).…”

“…Palladium‐catalyzed direct C‐4 arylation of 3,5‐dimethyl isoxazole has been reported by Doucet and co‐workers, using 1‐(bromophenyl)‐1,2,3‐triazoles as the arylating reagent (Scheme 15). A wide variety of heteroarenes such as thiazoles, thiophenes, furans, pyrroles and isoxazoles were tolerated [21] …”

Synthesis of Triazole-Fused Phenanthridines through Pd-Catalyzed Intramolecular Phenyl C–H Activation of 1,5-Diaryl-1,2,3-triazoles

“…Only one example of intramolecular cyclization was involved, in which a structurally complicated PdCl(C 3 H 5 )(dppb) catalyst was used under a relatively higher temperature. [17] Herein, we report an efficient Pd-catalyzed cyclization process to synthesize triazolophenanthridines, in which 1,5-diaryl-1,2,3-triazoles were applied as the substrates and the ortho-C-H bond of N( 1)-or C(5)-aryl was selectively arylated in the cyclization process (Scheme 1, d).…”

“…Another pivalate, namely NaOPiv, was also tested in this transformation and it seemed inferior to CsOPiv (Table 1, entry 15). Additionally, the amount of CsOPiv was also examined, and reducing the amount of CsOPiv to 2.0 equiv or increasing it to 4.0 equiv could not raise the yield evidently (Table 1, entries [16][17]. After further optimization, the best results were obtained by using 10 mol% Pd(OAc) 2 , 20 mol% PCy 3 and 3.0 equiv of CsOPiv in toluene at 130 °C for 24 hours, affording the desired compound 2a in 93% yield (Table 1, entry 14).…”