Direct Arylations via C–H Bond Functionalization of 1,2,3‐Triazoles by a Reusable Pd/C Catalyst Under Solvent‐Free Conditions

Abstract

Fully substituted triazoles are synthesized by a sustainable direct arylation reaction performed under solvent‐free conditions and in the presence of a recyclable Pd/C heterogeneous catalyst. Exclusion of air as well as anhydrous conditions are not required, enabling a convenient synthesis of 1,4,5‐trisubstituted 1,2,3‐triazoles and 1,2,3‐triazole‐fused isoindolines starting from 1,4‐disubstituted 1,2,3‐triazoles, easily prepared via click chemistry, and functionalized aryl iodides.

Peripherical thioester functionalization induces J-aggregation in bithiophene-DPP films and nanoparticles

“…The two DPP derivatives were synthesized through a palladium-catalysed Suzuki-Miyaura coupling, a straightforward metal-catalyzed cross-coupling reaction. 24,25 Synthetic details are provided in the ESI. † First, we performed the electrochemical and the optical characterization of the two dyes in solution.…”

Infrared Irradiation‐Assisted Solvent‐Free Pd‐Catalyzed (Hetero)aryl‐aryl Coupling via C−H Bond Activation

“…Supported Pd 0 catalysts were then investigated. 2 a was obtained in 25 % yield (C2/C3 ratio 90 : 10, entry 3) in the presence of Pd/C and tetra‐ n‐ butylammonium acetate (Bu 4 NOAc) as the base, [4a] while reaction yield increased to 59 % (C2/C3 ratio 99 : 1, entry 4) when Pd/C was used in the presence of P( o ‐MeOPh) 3 and Ag 2 CO 3 . Pd/AlO(OH) nanoparticles without any additive are unable to catalyze the direct arylation of 1 (entry 5).…”

“…Benzo[ b ]thiophene 1 and pentafluorobenzene 7 were purchased from Sigma Aldrich. 5‐Octylthieno[3,4‐c]pyrrole‐4,6‐dione 3 was purchased from TCI Europe and SunaTech Inc. 1‐Hexadecyl‐4‐phenyl‐1 H ‐1,2,3‐triazole 5 was prepared according to a literature procedure [4a] . Preparative column chromatography was performed using Macherey‐Nagel silica gel (60, particle size 0.063–0.2 mm).…”

“…Despite these advantages, only a few examples of solvent‐free direct arylation reactions have been reported thus far. [ 2a , 2b , 3 ] In this context and in the frame of our studies on synthetic methods for heterocyclic‐based conjugated structures, [4] we previously developed direct arylation protocols for the preparation of fully substituted 1,2,3‐triazoles [4a] and extended heteroaromatic conjugated molecules, [4b] performed in solvent‐free, non‐anhydrous conditions and without exclusion of air.…”

A recent overview on the synthesis of 1,4,5-trisubstituted 1,2,3-triazoles

“…Notably, the yield of the Click reaction with 2-iodotoluene decreased due to the steric effects. Moreover, the utilization of an efficient heterogeneous catalyst and insensitivity to air are advantages of this reaction ( Scheme 37 ) [ 60 ].…”