Activation of Alkynes by the Dinitrogen Complex Towards Catalytic Oligomerization and Cyclization Reactions

Article abstract of DOI:10.1007/BF00809210

The complex catalyses oligomerization and cyclization reactions of alkynes under mild conditions.Hence, alkyne cocyclotrimerization to benzene derivatives was mainly observed for ethyl propiolate, affording the three possible isomers of tricarbethoxybenzene; phenylacetylene undergoes mainly linear dimerization to trans-PhC<*>CCH=CHPh and trimerization; linear dimers are also the predominant products from 3-hexyne, but 1-octyne (with a long chain) undergoes mainly isomerization to 2-octyne; higher oligomers are also usually formed.Except for ethyl propiolate, hydrogenated dimers are detected in low yields (e.g. trans,trans-PhCH=CHCH=CHPh from phenylacetylene), whereas 3-hexene is formed in considerable yield from 3-hexyne.A novel type of cocyclization reaction with a nitrile (NCMe) appears to occur with phenylacetylene to give (although in low yield) 4,6-dimethyl-5-phenyl-pyrimidine.Alkynols are unreactive under the chosen conditions. - Keywords: Alkynes; Catalysis; Dinitrogen complex; Nitriles; Pyrimidine