Manganese-Catalyzed Regioselective C–H Lactonization and Hydroxylation of Fatty Acids with H<sub>2</sub>O<sub>2</sub>
Vladimir I. Kurganskiy, Roman V. Ottenbacher, М. В. Шашков, Evgenii P. Talsi, Denis G. Samsonenko⧫, Konstantin P. Bryliakov
Abstract
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 γ-lactones in 60-90% yields. Remarkably, by changing the reaction conditions, the oxidation of hexanoic acid can be diverted toward formation of δ-caprolactone in up to 67% yield. Furthermore, the possibility of obtaining (ω-1)-hydroxy derivatives from linear C7-C10 acids in up to 48% yields has been demonstrated.