the epoxidation of olefins with tetra n-butylammonium periodate, n-bu4/nio4, is catalyzed by six different tetrakis (4-substituted phenyl) porphyrinatomanganese(iii) acetate, mn(t4-xpp)oac, complexes in the presence of imidazole as an axial ligand with low to high yields and complete selectivity at room temperature. while the electronic effects of the highly electron-withdrawing no2 substituent...

We report a tetrazole-based, photoclick chemistry that can be employed to selectively functionalize an alkene genetically encoded in a protein inside E. coli cells. The reaction involved the treatment of E. coli cells with cell-permeable tetrazoles followed by a brief photo irradiation at 302 nm (4 min) and an overnight incubation at 4 degrees C. This in vivo alkene functionalization procedure ...

The insertion of an unsaturated ligand into a M-C or M-H bond proceeds through migratory insertion, a fundamental organometallic reaction. Recent literature documents evidence of the migratory insertion of alkenes into an M-O and M-N bonds for alkene alkoxylation and alkene amination reactions, respectively. Herein we provide an overview of the literature and a perspective on how these recent e...

A heterogeneous olefin epoxidation catalyst containing both V and Ti in the active site was prepared by sequential non-hydrolytic grafting. The silica was exposed first to VO(OPr)3 vapor followed by Ti(O Pr)4 vapor. Formation of propene is evidence for the creation of Ti-O-V linkages on the surface. Upon metathesis of the 2-propoxide ligands with BuOOH, the catalyst becomes active for the gas p...

Epoxidation of single-walled carbon nanotubes (SWNTs) may be carried out by the reaction of SWNTs with either trifluorodimethyldioxirane or 3-chloroperoxybenzoic acid; the resulting O-SWNTs are spectroscopically similar to those formed by ozonolysis. Quantification of the epoxide substituents is possible through the catalytic de-epoxidation reaction using MeReO3/PPh3 and the 31P NMR spectroscop...

Asymmetric epoxidation of various styrenes using carbocyclic oxazolidinone-containing ketone 3 has been investigated. High enantioselectivity (89-93% enantiomeric excess) has been attained for this challenging class of alkenes. Mechanistic studies show that substituents on the ketone catalyst can have electronic influences on secondary orbital interactions, which affects the competition between...

In this study we present evidence that one of two reactions of the xanthophyll cycle, violaxanthin de-epoxidation, may occur in unilamellar egg phosphatidylcholine vesicles supplemented with monogalactosyldiacylglycerol (MGDG). Activity of violaxanthin de-epoxidase (VDE) in this system was found to be strongly dependent on the content of MGDG in the membrane; however, only to a level of 30 mol%...

We characterized the inhibitory activity of several acetylenic and olefinic compounds on cytochrome P450 (CYP)-derived arachidonic acid omega-hydroxylation and epoxidation using rat renal cortical microsomes and recombinant CYP proteins. Among the acetylenic compounds, 6-(2-propargyloxyphenyl)hexanoic acid (PPOH) and N-methylsulfonyl-6-(2-propargyloxyphenyl)hexanamide were found to be potent an...

Several optically active Nb(salan) complexes were synthesized, and their oxidation catalysis was examined. A dimeric mu-oxo Nb(salan) complex that was prepared from Nb(OiPr)(5) and a salan ligand was found to catalyze the asymmetric epoxidation of allylic alcohols using a urea-hydrogen peroxide adduct as an oxidant with good enantioselectivity. However, subsequent studies of the time course of ...