Hydrophobic vitamin B₁₂. VII. ring-expanison reactions catalyzed by hydrophobic vitamin B₁₂ in octopus azaparacyclophane

Ring-expansion reactions of alkyl ligands bound to heptapropyl cobyrinate at the axial site of the nuclear cobalt were found to be markedly favoured in the hydrophobic cavity of an octopus azaparacyclophane, relative to reactions in methanol and benzene, under anaerobic photolysis conditions at 20.0°C. Heptapropyl cobyrinate perchlorate catalyzed the same ring-expansion reactions, which convert 2-methyl-1,3-cydopentanedione and 3-methyl-2-pyrrolidinone into 1,4-cyclohexanedione and 2-piperidinone, respectively, in the octopus cyclophane by utilizing vanadium trichloride as a co-catalyst under aerobic photolysis conditions.