THE COCYCLOTRIMERIZATION OF ALKYNES AND ACETONITRILE WITH CPCOCOD AS CATALYST

Mixtures of the alkynes and acetonitrile were cyclotrimerized with CpCoCOD as catalyst to form pyridine derivatives. The system can be thermally or photochemically activated. The cocyclotrimerization reaction is a pseudo first order process and the photochemically activated reaction at 20 degrees C has a rate constant of 3.66 x 10(-3) s(-1) while that of the thermally activated system at 140 degrees C is 4.23 x 10(-4) s(-1). The distribution of the products formed if a mixture of hex-l-yne, phenylacetylene and acetonitrile is used indicates an almost random coordination of the alkynes on the cobalt before the nitrile coordinates. The nitrile cocyclotrimerizes rather with a hex-l-yne containing intermediate than with the phenylacetylene containing intermediate to form pyridine derivatives.