An approach for the control and understanding of supported molecular catalysts is demonstrated with the design and synthesis of open and closed variants of a grafted Lewis acid active site, consisting of Al(III)-calix[4]arene complexes on the surface of silica. The calixarene acts as a molecular template that enforces open and closed resting-state coordination geometries surrounding the metal a...

The manganese(V) nitrido complex (PPh(4))(2)[Mn(N)(CN)(4)] is an active catalyst for alkene epoxidation and alcohol oxidation using H(2)O(2) as an oxidant. The catalytic oxidation is greatly enhanced by the addition of just one equivalent of acetic acid. The oxidation of ethene by this system has been studied computationally by the DFT method.

Self-assembled stacks of trimeric manganese porphyrins exhibit high activity in the photocatalytic epoxidation of stilbene using O2 as the oxidant. The supramolecular structure of the catalyst leads to increased stability of the system and enhances the stereoselectivity of the reaction.

A two-dimensional nanolayered polyoxomolybdate, [4,4´-H2bipy] [Mo7O22].H2O (1), where 4,4´-bipy = 4,4´-bipyridine, was prepared and characterized by FT-IR and atomic absorption spectroscopies, transmission electron microscopy (TEM), X-ray single crystal and powder diffraction (XRD), and thermogravimetric analysis. The catalytic performance of 1 was assessed in the epoxidation of some olefins em...

A detailed mechanistic study on the Mukaiyama epoxidation of limonene with dioxygen as oxidant, bis(acetylacetonato)nickel(II) as catalyst, and an aldehyde as co-reagent is reported. All major products of the reaction have been quantitatively identified, both with isobutyraldehyde and 2-methylundecanal as co-reacting aldehydes. Limonene epoxide is formed in good yield. The main products evolvin...

Sustainable solvent-free continuous flow epoxidation of biorenewable terpenes using a recyclable tungsten-based polyoxometalate phase transfer catalyst and benign H2O2 oxidant.

This work describes catalytic and asymmetric aziridinations (15 examples, 95-98% ee) of benzyl bromide and imines via the imino Corey-Chaykovsky reaction using (thiolan-2-yl)diarylmethanol benzyl ether as an organocatalyst. The catalyst and analogues thereof were prepared through an expeditious and efficient synthetic route featuring a double nucleophilic substitution and Shi epoxidation as key...

The epoxidation of alkenes was carried out over a CuO/Al(2)O(3) catalyst using cumene as an oxygen carrier, through a one-pot reaction, giving high conversion and selectivity with different substrates. Trans-β-methylstyrene gave the corresponding epoxide in 95% yield after 3 h.

A study, via isotopic labeling, of the stereoselective processes in a Shi-type epoxidation, has revealed that the chiral platform provided by the catalyst mediates the transfer of the pro-S "O" of the related dioxirane species to the alkene in a doubly stereoselective manner.

Seven 2,3-epoxy-1-phenyl-3-aryl-1-propanones were synthesized via epoxidation of the corresponding 1-phenyl-3-aryl-2-propen-1-ones with 30% aqueous hydrogen peroxide in 74-99% yields using benzyldimethyltetradecylammonium chloride as phase transfer catalyst under ultrasound irradiation.