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

Graphical A facile ZnCl 2 -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 S N 2/Thorpe–Ziegler cyclization/Friedländer reaction to give fused pyridines in moderate to good yields. A ZnCl 2 -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 S N 2 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.