Two-step AdE reaction of dicobalthexacarbonyl complexes of conjugated enynes with independent variation in the nature of the electrophile and nucleophile

1. Reactions of dicoboalt hexacarbonyl complexes of conjugated enynes with cationoid reagents of the type acyl-, alkyl-, nitronium, and arylsulfene-tetrafluoroborates leads to formation of cationoid intermediates which are stable in solution. These cationoid intermediates may then react with nucleophiles of the water or methanol type with formation of covalent adducts. 2. The observed two-step AdE-reaction is a suitable route for synthetic use of enynes, which is shown for the case of the syntheses of a number of monoterpenoids.