Isomerisation of α-pinene oxide in the presence of indenyl allyl dicarbonyl molybdenum(II) and tungsten(II) complexes

The indenyl complexes IndM(η3-C3H5)(CO)2 (M = Mo (1), W (2)), (IndMe)Mo(η3-C3H5)(CO)2 (3) and (IndSiMe3)Mo(η3-C3H5)(CO)2 (4) display catalytic activity for the isomerisation of α-pinene oxide. Conversion reached 97% after 3 h at 35 °C in the presence of 1 and 1,2-dichloroethane as solvent, giving campholenic aldehyde in 56% yield. Solvent polarity and basicity appear to affect the reaction rate. Whereas the type of substituent on the indenyl ligand does not appear to have a strong impact on catalytic performance, changing the metal centre from Mo (1) to W (2) gave a significantly more active catalyst.

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► Indenyl allyl dicarbonyl derivatives catalyse the isomerisation of α-pinene oxide.
► Solvent polarity and basicity appear to affect the reaction rate.
► Campholenic aldehyde is the major product formed in ca. 55% yield.
► IndW(η3-C3H5)(CO)2 displays significantly higher activity than its Mo congener.