Biomimetic iron-catalyzed asymmetric epoxidation of aromatic alkenes by using hydrogen peroxide.

A novel and general biomimetic non-heme Fe-catalyzed asymmetric epoxidation of aromatic alkenes by using hydrogen peroxide is reported herein. The catalyst consists of ferric chloride hexahydrate (FeCl(3)6 H(2)O), pyridine-2,6-dicarboxylic acid (H(2)(pydic)), and readily accessible chiral N-arenesulfonyl-N'-benzyl-substituted ethylenediamine ligands. The asymmetric epoxidation of styrenes with this system gave high conversions but poor enantiomeric excesses (ee), whereas larger alkenes gave high conversions and ee values.

Development of a general and efficient iron-catalyzed epoxidation with hydrogen peroxide as oxidant.

The development of inexpensive and practical iron catalysts for the environmentally benign epoxidation of olefins with hydrogen peroxide as terminal oxidant is described. By systematic variation of ligands, metal sources, and reaction conditions, it was discovered that FeCl3 x 6 H2O in combination with pyridine-2,6-dicarboxylic acid and different amines shows high reactivity and excellent selectivity towards the epoxidation of aromatic olefins and moderate reactivity towards that of aliphatic olefins.

An efficient biomimetic Fe-catalyzed epoxidation of olefins using hydrogen peroxide.

A new, environmentally benign and practical epoxidation method was developed using inexpensive and efficient Fe catalysts. FeCl3.6H2O in combination with commercially available pyridine-2,6-dicarboxylic acid and amines showed excellent reactivity and selectivity towards aromatic olefins and moderate reactivity towards 1,3-cyclooctadiene utilizing H2O2 as the terminal oxidant.

3,3,6,6-Tetramethyl-1,2,4,5-tetroxane: a twinned crystal structure.

The title compound, C6H12O4, also known as dimeric acetone peroxide, Me2(C2O4)Me2, has crystallographically imposed inversion symmetry and adopts a chair conformation in the solid state. This structure contrasts with that of the sulfur homologue Me2(C2S4)Me2, which has crystallographically imposed -4 symmetry and crystallizes in a twist-boat conformation. Crystals of the title compound are twinned along the reciprocal c* axis.

Chemoselective electrophilic oxidation of heteroatoms by hydroperoxy sultams.

The synthesis of novel hydroperoxy sultams 1b-d and their potential as renewable chemoselective electrophilic oxidants for a wide range of nitrogen, sulfur, and phosphorus heteroatoms in nonaqueous media is described. Reactions of 1b,c with secondary amines 10f,g yielded the hydroxysultams 2b,c and nitrone 11f or radical 11g depending on the substrate and stoichiometry, while tertiary amines 10a-d gave amine oxides 11a-d. Compounds 1c,d oxidized various thioethers 12a-g to sulfoxides 13a-g smoothly that were isolated by chromatography in nearly quantitative yields.

Chemoselective C-H oxidation of alcohols to carbonyl compounds with iodosobenzene catalyzed by (salen)chromium complex.

Primary and secondary alcohols with benzylically and allylically activated C-H bonds are chemoselectively oxidized to the corresponding carbonyl compounds by the (salen)Cr(III) complex I as the catalyst and iodosobenzene as the oxygen source; the oxidizing species is the Cr(V) oxo complex. Allylic alcohols with fully substituted double bonds give appreciable amounts of epoxides besides the C-H oxidation products enones, while saturated alcohols are less readily oxidized.