A Metal-Free Based New Approach to 2,4-Disubstituted Pyridines via One-Pot Sequential Reaction of Cyclic Sulfamidate Imines with β-Substituted Acroleins

Abstract

A novel and efficient L-proline catalyzed Michael reaction of several 4-aryl/heteroaryl-substituted cyclic sulfamidate imines with a variety of β-styryl/aryl/alkyl-substituted acroleins, followed by in situ elimination-iminocyclization-dehydration sequence process in the presence of DABCO as a base is reported for the first time. By this unconventional one-pot sequential protocol, a number of 2-aryl/heteroaryl-4-styrylpyridines and 2,4-diarylpyridines have been prepared in good to high yields under metal-free conditions. Besides, the synthesized 4-styrylpyridine derivatives were also further utilized for the synthesis of commercially as well as pharmaceutically important 2-arylisonicotinic acids. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim