Pd-Catalyzed Regioselective Arylation on the C‑5 Position of N‑Aryl 1,2,3-Triazoles

• Published in: Journal of organic chemistry 2015-03, Vol.80 (6), p.3003-3011
• Main Authors: Yamajala, K. Durga Bhaskar, Patil, Mahendra, Banerjee, Shaibal
• Format: Article
• Language: English
• Subjects: Catalysis; Molecular Structure; Organometallic Compounds - chemical synthesis; Organometallic Compounds - chemistry; Palladium - chemistry; Quantum Theory; Stereoisomerism; Triazoles - chemical synthesis; Triazoles - chemistry
• ISSN: 0022-3263; 1520-6904
• DOI: 10.1021/jo5026145

We herein report a highly efficient method for the arylation at the C-5 position of N-aryl 1,2,3-triazoles via a direct palladium catalyzed arylation reaction. The optimal reaction conditions required a combination of Pd(OAc)2 and tris(o-tolyl)phosphine as catalyst, and Cs2CO3 as the base under inert atmosphere. A variety of C-5 substituted N-aryl 1,2,3-triazoles were prepared using these conditions with yields in the 70–88% range. Regioselective C-5 arylations were also performed on 1,4-disubstituted 1,2,3-triazoles. The regioselectivity in triazole substitution at the C-5 position was confirmed by single crystal XRD. In addition, computational investigations of key steps of the catalytic cycle using the density functional theory have provided a rationalization to the selective C-5 arylation of N-aryl 1,2,3-triazoles.