Catalytic Isomerisation of Water-Soluble Quadricyclane to Norbornadiene Derivatives Induced by Cobalt-Porphyrin Complexes

Article abstract of DOI:10.1021/jo00355a006

In an aqueous alkaline solution, the exothermic isomerisation of quadricyclane derivatives to norbornadiene derivatives catalyzed by cobalt-porphyrin complexes was investigated.By catalytic action of cobalt 5,10,15,20-tetrakis(p-carboxyphenyl)porphyrin (Co-TPPC), thermally stable and water-soluble quadricyclane derivatives 1a-l isomerised to the corresponding norbornadiene derivatives 2a-l quantitatively and suddenly even at room temperature in an aqueous sodium carbonate solution.It was seen that larger hydrophobicities of 1 enhanced the isomerization rate.The attacking direction of cobalt porphyrins toward quadricyclanes might be to the five-membered ring, which was different from that suggested in the action of Rh catalyst, i.e., attack to the three-membered ring.