Aqueous-phase, thermal Pauson-Khand reactions in the presence of surfactants

Efficient stoichiometric Pauson-Khand reactions were realized in water as the only solvent, and in the presence of surfactants as additives. Use of the cationic surfactant CTAB provided good yields of cyclopentenones from the thermal reactions of pre-formed dicobalthexacarbonyl complexes of enynes and alkynes. The water-CTAB medium was found to be less effective with Co₄(CO)₁₂ as the promoter of the reaction. Incidentally, these results have provided a strictly water-based PKR protocol under very mild and convenient conditions.