Manganese complexes with non-porphyrin N ligands as recyclable catalyst for the asymmetric epoxidation of olefins

• Published in: Catalysis science & technology 2013-12, Vol.4 (1), p.28-217
• Main Authors: Maity, Nabin Ch, Kumar Bera, Prasanta, Ghosh, Debashis, Abdi, Sayed H. R, Kureshy, Rukhsana I, Khan, Noor-ul H, Bajaj, Hari C, Suresh, E
• Format: Article
• ISSN: 2044-4753; 2044-4761
• DOI: 10.1039/c3cy00528c

New chiral manganese complexes of N 4 ligands derived from 2-acetylpyridine were prepared and used as catalysts in the enantioselective epoxidation of olefins, using H 2 O 2 as an oxidant to give epoxides, with excellent conversions (up to 99%) and enantiomeric excess (up to 88%) within 1 h at 0 °C. A detailed mechanistic study was undertaken based on the information obtained by single crystal X-ray, optical rotation, UV-Vis, CD spectra and kinetic studies, and revealed that the reaction is first order with respect to the concentration of catalyst and oxidant and independent of substrate concentration. The complex (0.1 mol%) was successfully subjected to recyclability experiments over 3 cycles in the epoxidation of styrene with H 2 O 2 as an oxidant and acetic acid as an additive at 0 °C with retention of performance. Chiral manganese complexes of N 4 ligands derived from 2-acetylpyridine were used in the epoxidation of olefins, using H 2 O 2 as an oxidant to give epoxides, with conversions (up to 99%) and enantiomeric excess (up to 88%) within 1 h at 0 °C.