Synthesis of 2,5‐bis‐arylpyridines by [4 + 2] cycloaddition of 1,4‐bis aryl‐2‐aza‐1,3‐butadienes with electron‐poor dienophiles

Tetrahydropyridines 4a, 4b, 4c and pyridines 7a, 7b, 7c, 9a, 9b, 9c were synthesized by a 4 + 2] cycloaddition between 1,4‐bis aryl‐2‐aza‐1,3‐butadienes and electron‐poor dienophiles. Dimeric cycloadducts 6a, 6b, 6c , were also isolated indicating a competition between the expected Hetero Diels‐Alder and a dimerization process.