Methyltrioxorhenium (MTO) catalysis in the epoxidation of alkenes: a synthetic overview

Epoxides are biologically important moiety that is also used as synthetic intermediates. This review aims to present the up-to-date advancements in methyltrioxorhenium (MTO)-catalyzed epoxidation of alkenes using diverse oxidizing agents.

New Sustainable Synthetic Routes to Cyclic Oxyterpenes Using the Ecocatalyst Toolbox

Cyclic oxyterpenes are natural products that are mostly used as fragrances, flavours and drugs by the cosmetic, food and pharmaceutical industries. However, only a few cyclic oxyterpenes are accessible via chemical syntheses, which are far from being ecofriendly. We report here the synthesis of six cyclic oxyterpenes derived from ß-pinene while respecting the principles of green and sustainable chemistry. Only natural or biosourced catalysts were used in mild conditions that were optimised for each synthesis. A new generation of ecocatalysts, derived from Mn-rich water lettuce, was prepared via green processes, characterised by MP-AES, XRPD and TEM analyses, and tested in catalysis. The epoxidation of ß-pinene led to the platform molecule, ß-pinene oxide, with a good yield, illustrating the efficacy of the new generation of ecocatalysts. The opening ß-pinene oxide was investigated in green conditions and led to new and regioselective syntheses of myrtenol, 7-hydroxy-α-terpineol and perillyl alcohol. Successive oxidations of perillyl alcohol could be performed using no hazardous oxidant and were controlled using the new generation of ecocatalysts generating perillaldehyde and cuminaldehyde.

Coordination-Driven Hierarchical Assembly of Hybrid Nanostructures Based on 2D Materials

2D materials have received tremendous scientific and engineering interests due to their remarkable properties and broad-ranging applications such as energy storage and conversion, catalysis, biomedicine, electronics, and so forth. To further enhance their performance and endow them with new functions, 2D materials are proposed to hybridize with other nanostructured building blocks, resulting in hybrid nanostructures with various morphologies and structures. The properties and functions of these hybrid nanostructures depend strongly on the interfacial interactions between 2D materials and other building blocks. Covalent and coordination bonds are two strong interactions that hold high potential in constructing these robust hybrid nanostructures based on 2D materials. However, most 2D materials are chemically inert, posing problems for the covalent assembly with other building blocks. There are usually coordination atoms in most of 2D materials and their derivatives, thus coordination interaction as a strong interfacial interaction has attracted much attention. In this review, recent progress on the coordination-driven hierarchical assembly based on 2D materials is summarized, focusing on the synthesis approaches, various architectures, and structure-property relationship. Furthermore, insights into the present challenges and future research directions are also presented.

A heterogenized chiral imino indanol complex of manganese as an efficient catalyst for aerobic epoxidation of olefins

A new composite was synthesized by grafting the (1R,2S)-1-(N-salicylideneamino)-2-indanol complex of Mn onto graphene oxide/Fe₃O₄@C. It catalysed the aerobic epoxidation of olefins with a selectivity of >98% and enantioselectivity of >99%.

Influence of alkenyl structures on the epoxidation of unsaturated fatty acid methyl esters and vegetable oils

Epoxidation of three fatty acid methyl esters (FAMEs) were carried out with peroxyacid catalysts to investigate the influences of the alkenyl structure on the epoxidation efficiency and selectivity.

Preparation of SnO2/graphene nanocomposite and its application to the catalytic epoxidation of alkenes with H2O2

The SnO₂/graphene nanocomposites have been achieved via hydrothermal method and used as an efficient catalyst for the epoxidation of alkenes with H₂O₂ in nitrile based systems for the first time.

Ionic liquid-functionalized graphene oxide as an efficient support for the chiral salen Mn(iii) complex in asymmetric epoxidation of unfunctionalized olefins

Chiral salen Mn(iii) complex covalently grafted on IL-functionalized GO sheet, was a highly efficient, universal and reusable catalyst for asymmetric epoxidation of unfunctionalized olefins using aqueous NaOCl as an oxidant.