1115189-22-4Relevant articles and documents
Synthesis of substituted 2,2′-bipyridines and 2,2′:6′, 2″-terpyridines by cobalt-catalyzed cycloaddition reactions of nitriles and α,ω-diynes with exclusive regioselectivity
Goswami, Avijit,Ohtaki, Kazuhiko,Kase, Kouki,Ito, Taichi,Okamoto, Sentaro
supporting information; scheme or table, p. 143 - 152 (2009/04/07)
A variety of substituted 2,2′-bipyridines were synthesized by a 1,2-bis(diphenylphosphino)-ethane (dppe)/cobalt chloride hexahydrate (CoCl 2·6H2O)/zinc-catalyzed [2 + 2+2] cycloaddition reaction of diynes and nitriles, with all reactions exhibiting exclusive regioselectivity. Thus, symmetrical and unsymmetrical 1,6-diynes and 2-cyanopyridine reacted in the presence of 5 mol % of dppe, 5 mol % of CoCl 2·6H2O and 10 mol% of zinc powder to provide the corresponding 2,2′-bipyridines. Under identical reaction conditions, 1-(2-pyridyl)-1,6-diynes and nitriles reacted smoothly with exclusive regioselectivity to produce 2,2′-bipyridines in good yield. 2,2′-Bipyridines were also obtained by the double [2 + 2 + 2] cycloaddition reaction of 1,6,8,13-tetraynes with nitriles. Similarly, 2,2′:6′,2″-terpyridines were synthesized from 1-(2-pyridyl)-1,6-diyne and 2-cyanopyridine. The regiochemistry observed can be explained by considering the electronic nature of cobaltacyclopentadiene intermediates and nitriles. A survey of the exclusive regiochemical trend gives reasonable credence to the synthetic potential of the present method.
