Zirconocene-mediated multicomponent reactions of 1,3-butadiynes with ylidenemalononitriles in the absence or presence of CuCl have been developed. In the absence of CuCl, 1,3-butadiyne couples with three molecules of ylidenemalononitriles to yield azazirconacycles bearing a hexahydro-1,8-naphthyridine skeleton with high stereoselectivity. In the presence of CuCl, cyclopenta[b]pyridine or cyclopenta[b] quinolin-1-one derivatives are obtained via transmetalation of Zr-C bond to Cu-C bond as the key reaction step. These domino-type reactions proceed with high chemo-, regio- and/or stereoselectivities, and allowing the formation of multiple C-N and C-C bonds in a single operation.
Yu SS,Sun RH,Chen HY,et al. Zirconium-Mediated Multicomponent Reactions of 1,3-Butadiynes with Ylidenemalononitriles to Form Functionalized 1,8-Naphthyridine and Cyclopenta[b]pyridine Derivatives[J]. Chem.-Eur. J.,2015,21(4):1420-1424.