NEW SYNTHETIC ROUTES TO 3-ARYL-2-CHLOROPYRIDINES, 5-ARYL-2-CHLOROPYRIDINES, AND 6-ARYL-2-CHLOROPYRIDINES

The efficient synthesis of 3-, 5-, and 6-aryl-2-chloropyridines via the facile preparation of 5-(dimethyamino)aryl-substituted pentadienyl nitriles and cyclization with hydro chloric acid is described. This approach allows for the introduction of other electron-withdrawing substituents on the pyridine ring as well as the preparation of the desired unsubstituted arylpyridines. Some differences in the rates of cyclization of the pentadienyl nitriles as well as the yields of chloropyridines were observed that depended on the position and degree of substitution in the aryl substituent. The arylpentadienyl nitriles 5 and 6 could also be converted directly into the corresponding 2-aminopyridines.