Ti-salalen mediated asymmetric epoxidation of olefins with H2O2: Effect of ligand on the catalytic performance, and insight into the oxidation mechanism

Ti-salalen mediated asymmetric epoxidation of olefins with H2O2: Effect of ligand on the catalytic performance, and insight into the oxidation mechanism Научная публикация

Журнал

Journal of Molecular Catalysis A: Chemical
ISSN: 1381-1169

Вых. Данные

Год: 2016, Том: 421, Страницы: 131-137 Страниц : 7 DOI: 10.1016/j.molcata.2016.05.019

Ключевые слова

Asymmetric oxidation; Hydrogen peroxide; Mechanism; Salalen; Titanium

Авторы

Talsi Evgenii P. ^1,2 , Rybalova Tatyana V. ^1,3 , Bryliakov Konstantin P. ^1,2

Организации

1	(Данные Web of science) Novosibirsk State Univ, Ul Pirogova 2, Novosibirsk 630090, Russia
2	(Данные Web of science) Boreskov Inst Catalysis, Pr Lavrentieva 5, Novosibirsk 630090, Russia
3	(Данные Web of science) Vorozhtsov Novosibirsk Inst Organ Chem, Pr Lavrentieva 9, Novosibirsk 630090, Russia

The highly enantioselective epoxidation of several conjugated olefins with H2O2 in the presence of five chiral titanium(IV) salalen (dihydrosalen) complexes has been studied, with focus on the effects of substituents (electronic and steric) on the epoxide yield and enantioselectivity. The introduction of electron acceptors at the ligand's remote positions enhances the catalytic reactivity, without drastic effect on the stereoselectivity and ultimate catalytic efficiency. In turn, the replacement of Ph substituents of the ligand core with o-MeO-Ph and o-Et-Ph substituents leads to the enhancement in enantioselectivity (up to 99.8% ee), conversion (up to 100%) and efficiency (up to 125 TN). Kinetic and Hammett data provide evidence in favour of a stepwise epoxidation mechanism on Ti-salalen catalysts. As compared to Ti-salan protagonists, Ti-salalen catalysts exhibit much higher activity and efficiency, and in most cases comparable enantioselectivity. Kinetic peculiarities of epoxidations on Ti-salalen and Ti-salan complexes are considered. (C) 2016 Published by Elsevier B.V.

Talsi E.P. , Rybalova T.V. , Bryliakov K.P.
Ti-salalen mediated asymmetric epoxidation of olefins with H2O2: Effect of ligand on the catalytic performance, and insight into the oxidation mechanism
Journal of Molecular Catalysis A: Chemical. 2016. V.421. P.131-137. DOI: 10.1016/j.molcata.2016.05.019 WOS Scopus РИНЦ

Опубликована в печати:

1 сент. 2016 г.

Web of science	WOS:000380075300015
Scopus	2-s2.0-84971010719
РИНЦ	27155687
OpenAlex	W2396606384