Chiral MnIII (salen) complex supported on modified ZPS-PVPA (zirconium poly(styrenephenylvinylphosphonate)) and ZPS-IPPA (zirconium poly(styrene-isopropenyl phosphonate)) were prepared using –CH2Cl as a reactive surface modifier by a covalent grafting method. The supported catalysts showed higher chiral induction (ee: 72%–83%) compared with the corresponding homogeneous catalyst (ee: 54%) for a...

The mechanism of alkene epoxidation by chromium(v) oxo salen complexes has been studied by DFT and experimental methods. The reaction is compared to the closely related Mn-catalyzed process in an attempt to understand the dramatic difference in selectivity between the two systems. Overall, the studies show that the reactions have many similarities, but also a few critical differences. In agreem...

Alkene monooxygenase (AMO) from Rhodococcus rhodochrous B-276 is a 3-component enzyme system encoded by the 4-gene operon amoABCD, which catalyzes the stereoselective epoxidation of aliphatic alkenes yielding primarily the R enantiomer. With propene as the substrate, wild-type AMO yields R-epoxypropane with an enantiomeric excess (e.e.) of 83%. The presumed site of alkene oxidation is a dinucle...

mn(tpp)cl catalyzes cooxidation of olefin in the singlet oxygenation of sulfid. mn(tpp)cl is able to transfer an oxygen atom from a peroxidic intermediate generated in singlet oxygenation of sulfide to a metal ion affording metal 0x0 species which is responsible for epoxidation. this system leads to allcenes epoxidation such as styrene and cyclooctene. epoxidation of cyclohexene produces cycloh...

An overview of the synthesis and applications of chiral 2,3-epoxy alcohols containing unsaturated chains is presented. One of the fundamental synthetic routes to these compounds is Sharpless asymmetric epoxidation, which is reliable, highly chemoselective and enables easy prediction of the product enantioselectivity. Thus, unsaturated epoxy alcohols are readily obtained by selective oxidation o...

Benign Method for Alkene Epoxidations Benjamin S. Lane and Kevin Burgess* Department of Chemistry, Texas A & M UniVersity PO Box 30012, College Station, Texas 77842-3012 ReceiVed NoVember 17, 2000 This paper reports a simple method wherein manganese (2+) salts, for example, MnSO4, catalyze epoxidation of alkenes using 30% aqueous hydrogen peroxide as the terminal oxidant. The reactions are perf...

The importance of chiral epoxides as synthetic building blocks in asymmetric synthesis is extremely difficult to overstate. While the highly enantioselective Sharpless, and JacobsenKatsuki, protocols for the epoxidation of internal alkenes are nowmature technologies of inestimable value, the conversion of terminal alkenes to enantioenriched 1-oxiranes has proven a considerably more difficult pr...

The functionalization of alkenes is one the most important conversions in synthetic chemistry to prepare numerous fine chemicals. Typical procedures, such as hydrosilylation and hydroformylation, are traditionally catalyzed using homogeneous noble metal complexes, while highly reactive stable heterogeneous single-atom catalysts (SACs) now provide alternative approaches fulfill these by combinin...

Multi-step cascade reactions have gained increasing attention in the biocatalysis field recent years. In particular, multi-enzymatic cascades can achieve high molecular complexity without workup of reaction intermediates thanks to enzymes’ intrinsic selectivity; and where enzymes fall short, organo- or metal catalysts further expand range possible synthetic routes. Here, we present two enantioc...

vo2+ and its complexes with ethylenediamine (en), acetylacetonate (acac), 2, 2’-bipyridine(bpy) ligands, immobilized within nanoreactors of al-mcm-41 designated as vo2+/al-mcm-41 or vol2/al-mcm-41, were prepared and characterized by x-ray powder diffraction (xrd), ft-ir, bet nitrogen adsorption-desorption and chemical analysis techniques. vo2+/al-mcm-41 and vol2/al-mcm-41 were found to catalyze...