Reaction of Pyridine with Phenylcyanoacetylene: A New Route to Functionalized Polyconjugated 1,4‐Dihydropyridine Systems
Pyridine reacts with phenylcyanoacetylene under mild conditions (20–25 °C, no catalyst) to unexpectedly give the 2:3 adduct — a C,N-functionalized polyconjugated 1,4-dihydropyridine system — containing two 1,4-dihydropyridine cycles and four vinylene units formed by three molecules of phenylcyanoacetylene (the yield is up to 46 %). Other products are higher oligomers of phenylcyanoacetylene terminated by 1,4-dihydropyridine cycles (approx. 30 % yield). Assembly of the 2:3 adduct proceeds regio- and stereoselectively — only one of the possible isomers is formed. The oligomers show paramagnetic and electroconductive properties. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)