Stable catalyst for intermolecular Pauson-Khand reaction

The catalytic activity of previously formed Co-2(CO)(6)[P(Ph)(3)](2) (1) was compared with Co-2(CO)(8) and the system formed by Co-2(CO)(8) plus PPh3 in the intermolecular Pauson-Khand (PK) reaction between norbornadiene and phenylacetylene. The effects of pressure, catalyst concentration and temperature were also studied. Additionally, the catalytic activity of complex I was compared with Co-2(CO)(6)[P(OPh)(3)](2) (2) in the intermolecular PK reaction between strained alkenes and terminal and non-terminal afkynes. Both catalysts are very stable, quite efficient and interestingly complex 2 leads to double PK reaction. The results indicate that these complexes are attractive alternatives to Co-2(CO)(8) as catalyst and in addition, complex 2 is an alternative catalyst for double cyclocarbortylation reaction. (c) 2005 Elsevier B.V. All rights reserved.