Transition metal-mediated oxidations utilizing monomeric iodosyl- and iodylarene species

Several transition metal-mediated oxidations using hypervalent iodine species are reported. A convenient procedure for preparation of iodylarenes via RuCl₃-catalyzed oxidation of iodoarenes has been developed. This procedure allows the generation of highly reactive monomeric iodine(V) species, which are excellent oxidants toward alcohols and hydrocarbons in situ. A broad range of substrates can be oxidized to carbonyl compounds by a tandem catalytic system based on the Ru(III)-catalyzed reoxidation of ArIO to ArIO₂ using Oxone^® as oxidant. It was shown that electrophilic iodine(III) species, originating from oligomeric iodosylbenzene sulfate (PhIO)₃SO₃, are efficient oxygenating agents in catalytic oxidation of aromatic hydrocarbons in the presence of metalloporphyrin complexes.     

Preparation and X-ray structures of 3-[Bis(trifluoroacetoxy)iodo]benzoic acid and 3-[hydroxy(tosyloxy)iodo]benzoic acid: new recyclable hypervalent iodine reagents

Preparation, structural characterization, and reactivity of 3-[bis(trifluoroacetoxy)iodo]benzoic acid and 3-[hydroxy(tosyloxy)iodo]benzoic acid, new recyclable iodine(III) reagents derived from 3-iodosylbenzoic acid, are described. The reduced form of these reagents, 3-iodobenzoic acid, can be easily recovered from the reaction mixtures using ion-exchange resin or basic aqueous workup followed by acidification with HCl.     

2-iodylphenol ethers: preparation, X-ray crystal structure, and reactivity of new hypervalent iodine(V) oxidizing reagents

2-Iodylphenol ethers were prepared by the dimethyldioxirane oxidation of the corresponding 2-iodophenol ethers and isolated as chemically stable, microcrystalline products. Single-crystal X-ray diffraction analysis of 1-iodyl-2-isopropoxybenzene 8c and 1-iodyl-2-butoxybenzene 8d revealed pseudopolymeric arrangements in the solid state formed by intermolecular interactions between IO2 groups of different molecules. 2-Iodylphenol ethers can selectively oxidize sulfides to sulfoxides and alcohols to the respective aldehydes or ketones.     

Design, preparation, X-ray crystal structure, and reactivity of o-alkoxyphenyliodonium bis(methoxycarbonyl)methanide, a highly soluble carbene precursor

The preparation, X-ray structure, and reactivity of new, highly soluble, and reactive iodonium ylides derived from malonate methyl ester and bearing an ortho substituent on the phenyl ring are reported. These new reagents show higher reactivity than common phenyliodonium ylides in the Rh-catalyzed cyclopropanation, C-H insertion, and transylidation reactions under homogeneous conditions.     

Magnetic discontinuities in magnetohydrodynamic turbulence and in the solar wind

Recent measurements of solar wind turbulence report the presence of intermittent, exponentially distributed angular discontinuities in the magnetic field. In this Letter, we study whether such discontinuities can be produced by magnetohydrodynamic (MHD) turbulence. We detect the discontinuities by measuring the fluctuations of the magnetic field direction, Δθ, across fixed spatial increments Δx in direct numerical simulations of MHD turbulence with an imposed uniform guide field B(0). A large region of the probability density function (pdf) for Δθ is found to follow an exponential decay, proportional to exp(-Δθ/θ(*)), with characteristic angle θ(*)≈(14°)(b(rms)/B(0))(0.65) for a broad range of guide-field strengths. We find that discontinuities observed in the solar wind can be reproduced by MHD turbulence with reasonable ratios of b(rms)/B(0). We also observe an excess of small angular discontinuities when Δx becomes small, possibly indicating an increasing statistical significance of dissipation-scale structures. The structure of the pdf in this case closely resembles the two-population pdf seen in the solar wind. We thus propose that strong discontinuities are associated with inertial-range MHD turbulence, while weak discontinuities emerge from dissipation-range turbulence. In addition, we find that the structure functions of the magnetic field direction exhibit anomalous scaling exponents, which indicates the existence of intermittent structures.