Highly Regio- and Stereoselective Cocyclotrimerization and Linear Cotrimerization of α,β-Unsaturated Carbonyl Compounds with Alkynes Catalyzed by Nickel Complexes
degrees C affords the corresponding conjugatedtrienes 17a-c in 82-92% yields. The MS data of 17firmly support an adduct of two molecules of alkyne and a molecule of acrylate. Similarly, the reaction of 15a with octa-1,7-diyne in the presence of Ni(PPh(3))(2)I(2), ZnI(2), and zinc gives triene derivative 21 in 68% yield. NOE and X-ray results indicate that in these trienes the substituents from each alkyne