Nickel-catalyzed, directing-group-assisted [2+2+2] cycloaddition of imine and alkynes

Article abstract of DOI:10.1002/asia.201000564

An aldimine bearing a 3-methyl-2-pyridyl group undergoes [2+2+2] cycloaddition reaction with two alkyne molecules under nickel catalysis to afford a 1,2-dihydropyridine derivative in moderate to good yield. The reaction is likely to involve oxidative cyclization of the imine and alkyne, insertion of another alkyne, and C-N reductive elimination, followed by a 1,5-sigmatropic hydrogen shift. The pyridyl group is proposed to facilitate the reaction by chelation to the aza-nickelacycle intermediates. Copyright