ZnCl2-Promoted One-Pot Three-Component Synthesis of Multisubstituted Thiazolo[4,5-b]pyridines and Thieno[2,3-b:4,5-b′]dipyridines

A ZnCl2‐promoted one‐pot synthesis of multisubstituted thiazolo[4,5‐b]pyridines and thieno[2,3‐b:4,5‐b′]dipyridines from mercaptonitrile salts, α‐bromo ketones and ketones has been developed. This approach involves a tandem SN2 alkylation/Thorpe–Ziegler cyclization/Friedländer reaction, which allows the creation of two hetero rings and four new bonds in a single operation. The reaction proceeds smoothly under solvent‐free conditions to afford fused pyridines in moderate to good yields. A facile ZnCl2‐promoted one‐pot three‐component synthesis of thiazolo[4,5‐b]pyridines and thieno[2,3‐b:4,5‐b′]dipyridines is described. This approach involves a tandem SN2/Thorpe–Ziegler cyclization/Friedländer reaction to give fused pyridines in moderate to good yields.