Synthesis 2011(14): 2247-2254  
DOI: 10.1055/s-0030-1260068
SPECIALTOPIC
© Georg Thieme Verlag Stuttgart ˙ New York

Regioselective Syntheses of Substituted Pyridines and 2,2′-Bipyridines by Cobalt-Catalyzed [2+2+2] Cycloaddition of α,ω-Diynes with Nitriles

Yu-ki Sugiyama, Sentaro Okamoto*
Department of Material & Life Chemistry, Kanagawa University, 3-27-1 Rokkakubashi, Kanagawa-ku, Yokohama 221-8686, Japan
Fax: +81(45)4139770; e-Mail: okamos10@kanagawa-u.ac.jp;
Further Information

Publication History

Received 5 April 2011
Publication Date:
09 June 2011 (online)

Abstract

In the presence of a 1,2-bis(diphenylphosphino)ethane-cobalt(II) chloride-zinc catalyst in 1-methylpyrrolidin-2-one at room temperature to 50 ˚C, α,ω-diynes reacted with nitriles by a [2+2+2] cycloaddition pathway to give annulated pyridines or 2,2′-bipyridines. The regioselectivity of the reaction is controlled by a combination of steric and electronic effects. The reaction of diynes with a terminal trimethylsilyl group gave the corresponding 3-(trimethylsilyl)pyridines exclusively; these products could be proto- or halodesilylated to give the corresponding protonated or halogenated pyridines or 2,2′-bipyridines.