Manganese-Catalyzed Regioselective C-H Lactonization and Hydroxylation of Fatty Acids with H2O2

Herein, we report the direct selective C-H lactonization of fatty acids (C5-C16), catalyzed by manganese(II) complexes bearing bis-amino-bis-pyridine ligands. The catalyst system uses the environmentally benign hydrogen peroxide as oxidant and exhibits high efficiency (100-200 TON), providing under optimized conditions gamma-lactones in 60-90% yields. Remarkably, by changing the reaction conditions, the oxidation of hexanoic acid can be diverted toward formation of delta-caprolactone in up to 67% yield. Furthermore, the possibility of obtaining (omega-1)-hydroxy derivatives from linear C7-C10 acids in up to 48% yields has been demonstrated.

Automated summary

In this paper, the direct selective C-H lactonization of fatty acids (C5-C16) catalyzed by manganese(II) complexes bearing bis-amino-bis-pyridine ligands was reported. The catalyst system used environmentally benign hydrogen peroxide as an oxidant and showed high efficiency, providing gamma-lactones in 60-90% yields under optimized conditions. Remarkably, by changing the reaction conditions, the oxidation of hexanoic acid could be diverted to the formation of delta-caprolactone in up to 67% yield. Furthermore, the possibility of obtaining (omega-1)-hydroxy derivatives from linear C7-C10 acids in up to 48% yields was demonstrated.