Charles Mioskowski

The Chemistry of Vicinal Diamines

Especially in the field of enantioselective synthesis, vicinal diamines (1,2-diamines) 1 and compounds easily prepared from them-such as 1,2-bisimines, 1,2-diamides, or imidazolidin-2-ones-are widely used by organic chemists. Various strategies have been developed to produce these compounds selectively. Many natural products and medicinal agents also contain a 1,2-diamino unit.

Novel conversion of epoxides to one carbon homologated allylic alcohols by dimethylsulfonium methylide

Abstract The reaction of excess of dimethylsulfonium methylide with terminal, allylic, or benzylic epoxides affords good to excellent yields of one carbon homologated allylic alcohols.

ω-hydroxylation of Z9-octadecenoic, Z9,10-epoxystearic and 9,10-dihydroxystearic acids by microsomal cytochrome P450 systems from Vicia sativa

A microsomal fraction from etiolated Vicia sativa seedlings incubated aerobically with [1-14C]oleic acid (Z9-octadecenoic acid) or [1-14C]9,10-epoxystearic acid or [1-14C]9,10-dihydroxystearic acid catalyzed the NADPH-dependent formation of hydroxylated metabolites. The chemical structure of compounds formed from oleic, 9,10-epoxystearic or 9,10-dihydroxystearic acids was established by gas chromatography/mass spectra analysis to be 18-hydroxyoleic acid, 18-hydroxy-9,10-epoxystearic acid and 9,10,18-trihydroxystearic acid, respectively. The reactions required O2 and NADPH and were inhibited by carbon monoxide. As expected for monooxygenase reactions involving cytochrome P450, inhibition could be partially reversed by light and all three reactions were inhibited by antibodies raised against NADPH-cytochrome P450 reductase from Jerusalem artichoke. The omega-hydroxylation of the three substrates was enhanced in microsomes from clofibrate induced seedlings.

Enantioselective Synthesis of α‐Amino Acids and Monosubstituted 1,2‐Diamines by Conjugate Addition of 4‐Phenyl‐2‐oxazolidinone to Nitroalkenes

The addition of the potassium salt of (R)- or (S)-4-phenyl-2-oxazolidinone to monosubstituted nitroalkenes proceeded with very good diastereoselectivity. Several of the addition products were converted into α-amino acids and monosubstituted 1,2-diamines of high enantiomeric purity.

Carbon nanotubes as templates for polymerized lipid assemblies

Amphiphilic molecules-molecules that have both hydrophobic and hydrophilic properties-can self-assemble in water to form diverse structures such as micelles, vesicles and tubes, and these nanostructures can be used for delivering drugs, stabilizing membrane proteins or as nanoreactors. We have previously shown that lipids can self-organize on the surface of single-walled carbon nanotubes into regular ring-shaped assemblies. Here we show that these lipid assemblies can be polymerized and isolated from the nanotube template by application of an electric field. We also demonstrate that these assemblies are monodispersed, water-soluble, and can dissolve various hydrophobic rylene dyes, fullerenes and membrane proteins. The stability of these constructs and their diverse applications will be useful in the fields of cosmetics, medicine and material sciences.

Direct conversion of tetrahydropyranylated alcohols to the corresponding bromides

Various tetrahydro-2 pyranyl protected alcohols are converted into the corresponding bromides by PPh3 / CBr4, with inversion of configuration, and in high yield.

Enol ethers: preparation and synthetic applications

Abstract A versatile preparation of α-alkoxyphosphonium bromides leading to enol ethers by Wittig coupling was exploited for the convergent synthesis of pheromones from the Douglas-fir tussock moth and the olive fly Dacus oleae as well as an oxaspirolactone and C-glycoside.

Triphenylphosphine hydrobromide: A mild and efficient catalyst for tetrahydropyranylation of tertiary alcohols

Abstract Triphenylphosphine hydrobromide is a convenient and highly effective catalyst for tetrahydropyranylation of tertiary alcohols with dihydropyran in dichloromethane at ambient temperature.

Lewis acid-catalyzed regiospecific opening of vinyl epoxides by alcohols

Abstract A Lewis acid-catalyzed, regiospecific opening of vinyl epoxides to β-hydroxy allyl-ethers was performed using equimolar quantities of both alcohols and oxiranes. BF 3 ·Et 2 O proved to be the most efficient catalyst for various substituted alcohols.

New conditions for the generation of nitrile oxides from primary nitroalkanes

Abstract Orginal dehydrating reagents for the efficient formation of nitrile oxides from primary nitro compounds are reported. Burgess salt, DAST, acetic anhydride and oxalyl chloride were shown to be useful reagents to perform this transformation.