Utilizing perhalopyridine-based alkynes as suitable precursors for the synthesis of novel poly(1,2,3-triazolyl)-substituted perhalopyridines

Abstract

A novel series of poly(1,2,3-triazolyl)-substituted perhalopyridines 5a–f were successfully synthesized from the click reaction of the terminal alkynes (drived from the nucleophilic substitution reactions of PFP 1a and PCP 1b with excess amounts of propargyl alcohol) with aryl azides 4a–c under ultrasonic irradiation. Likewise, the sonication of reaction mixtures containing pyridyl cores 3, alkyl bromides 6a,b, and NaN₃ under one-pot conditions afforded their respective aliphatic 1,2,3-triazoles 7a–d in yields ranging from 71% to 83%. We next developed an effective method for the regioselective preparation of 2,3,4,5-tetrachloro-6-(prop-2-yn-1-yloxy)pyridine 3c through S_NAr reaction of PCP with propargyl alcohol without the utilization of any catalyst. It was then used to fabricate several ((1,2,3-triazol-4-yl)methoxy)-3,4,5,6-tetrachloropyridines 8a–c under the reaction conditions. Finally, the Pd(PPh₃)₄-catalyzed SMC reaction of tris-triazoles 5b,e with arylboronic acids 9a–c offered a practical method for the synthesis of biaryl-embedded poly(1,2,3-triazoles) 10a–f in good yields.