LAUSR

Abstract Selective epoxidation of the (R) and (S) isomers of limonene by dioxomolybdenum (VI) complexes anchored covalently on TiO 2 nanotubes using UV–Vis light and O 2 as the oxidizing agent was evaluated. It is interesting to study the effect of the ligands: bipyridine, terpyridine, and Schiff base on the stereoselective epoxidation of limonene through photostimulated oxygen atom transfer (OAT). OAT activity observed to increase in the following order: Mo (VI) O 2 (Schiff base)/TiO 2 -NT < Mo (VI) Cl 2 O 2 (bipyridine)/TiO 2 -NT < Mo (VI) Cl 2 O 2 (terpyridine)/TiO 2 -NT. Moderate diastereoselectivity to the cis -isomer of complexes with “non-chiral” ligands like bipyridine and terpyridine was displayed. Contrary to the complex with the Schiff base as “chiral” ligand, it showed an increase in diastereoisomeric excess (52%), associated to an asymmetric double induction, assuming a complex metal-oxo sideway interaction with the trisubstituted olefins at the transition state. Graphic Abstract