A series of new hangman iron corroles with different electronic structure and pending aldehyde group were prepared and used as catalyst in B–V oxidation reactions. The results show that hangman iron corroles exhibit faster reaction rates and higher ε-caprolactone yields as compared to triaryl iron 5,10,15-tri(pentafluorophenyl) corrole (Fe(tpfc)Cl). The best hangman iron corrole bearing two pentafluorophenyl groups (FePXC) may give a yield of 97% at only 0.07 mol% catalyst loading.

Abstract

A series of new hangman iron corroles with different electronic structure and pending aldehyde group were prepared and used as catalyst in Baeyer–Villiger (B–V) oxidation reactions. The results show that hangman iron corroles exhibit faster reaction rates and higher ε-caprolactone yields as compared to triaryl iron 5,10,15-tri(pentafluorophenyl) corrole (Fe(tpfc)Cl). With the increase in the electron-withdrawing ability of the meso-position substituents of hangman iron corrole, the yield of caprolactone also increases. Under optimal conditions, the best hangman iron corrole bearing two pentafluorophenyl groups (FePXC) may give a yield of 97% at only 0.07 mol% catalyst loading. The turnover number (TON) of the FePXC catalyst could be up to 2100 in a gram-scale test of oxidation of cyclohexanone. This work demonstrates the good potential of hangman corroles in B–V oxidation.