J. Appl. Cryst.の発刊に際して

Starting from the early 1990’s, the chemistry of polyvalent iodine organic compounds has experienced an explosive development. This surging interest in iodine compounds is mainly due to the very useful oxidizing properties of polyvalent organic iodine reagents, combined with their benign environmental character and commercial availability. Iodine(III) and iodine(V) derivatives are now routinely used in organic synthesis as reagents for various selective oxidative transformations of complex organic molecules. Several areas of hypervalent organoiodine chemistry have recently attracted especially active interest and research activity. These areas, in particular, include the synthetic applications of 2-iodoxybenzoic acid (IBX) and similar oxidizing reagents based on the iodine(V) derivatives, the development and synthetic use of polymer-supported and recyclable polyvalent iodine reagents, the catalytic applications of organoiodine compounds, and structural studies of complexes and supramolecular assemblies of polyvalent iodine compounds.

The chemistry of polyvalent iodine has previously been covered in four books1–4 and several comprehensive review papers.5–17 Numerous reviews on specific classes of polyvalent iodine compounds and their synthetic applications have recently been published.18–61 Most notable are the specialized reviews on [hydroxy(tosyloxy)iodo]benzene,41 the chemistry and synthetic applications of iodonium salts,29,36,38,42,43,46,47,54,55 the chemistry of iodonium ylides,56–58 the chemistry of iminoiodanes,28 hypervalent iodine fluorides,27 electrophilic perfluoroalkylations,44 perfluoroorgano hypervalent iodine compounds,61 the chemistry of benziodoxoles,24,45 polymer-supported hypervalent iodine reagents,30 hypervalent iodine-mediated ring contraction reactions,21 application of hypervalent iodine in the synthesis of heterocycles,25,40 application of hypervalent iodine in the oxidation of phenolic compounds,32,34,50–53,60 oxidation of carbonyl compounds with organohypervalent iodine reagents,37 application of hypervalent iodine in (hetero)biaryl coupling reactions,31 phosphorolytic reactivity of o-iodosylcarboxylates,33 coordination of hypervalent iodine,19 transition metal catalyzed reactions of hypervalent iodine compounds,18 radical reactions of hypervalent iodine,35,39 stereoselective reactions of hypervalent iodine electrophiles,48 catalytic applications of organoiodine compounds,20,49 and synthetic applications of pentavalent iodine reagents.22,23,26,59

The main purpose of the present review is to summarize the data that appeared in the literature following publication of our previous reviews in 1996 and 2002. In addition, a brief introductory discussion of the most important earlier works is provided in each section. The review is organized according to the classes of organic polyvalent iodine compounds with emphasis on their synthetic application. Literature coverage is through July 2008.

Chemistry of Polyvalent Iodine

The preparation, structure, and chemistry of hypervalent iodine compounds are reviewed with emphasis on their synthetic application. Compounds of iodine possess reactivity similar to that of transition metals, but have the advantage of environmental sustainability and efficient utilization of natural resources. These compounds are widely used in organic synthesis as selective oxidants and environmentally friendly reagents. Synthetic uses of hypervalent iodine reagents in halogenation reactions, various oxidations, rearrangements, aminations, C–C bond-forming reactions, and transition metal-catalyzed reactions are summarized and discussed. Recent discovery of hypervalent catalytic systems and recyclable reagents, and the development of new enantioselective reactions using chiral hypervalent iodine compounds represent a particularly important achievement in the field of hypervalent iodine chemistry. One of the goals of this Review is to attract the attention of the scientific community as to the benefits of...

Advances in Synthetic Applications of Hypervalent Iodine Compounds

Bull. Chem. Soc. Jpn. への投稿のすすめ

Monofluorination of Organic Compounds: 10 Years of Innovation.

Elemental Iodine or Diphenyl Diselenide in the [Bis(trifluoroacetoxy)iodo]benzene‐Mediated Conversion of Alkynes into 1,2‐Diketones

Two new N-salicylidene-N ‘-aroylhydrazines ligands have been prepared:  N-4-diethylaminosalicylidene-N ‘-4-nitrobenzoyl-hydrazine (L1) and N-4-diethylaminosalicylidene-N ‘-4-(4-nitrophenylethylidene)-benzoyl-hydrazine (L2). The ligands are properly functionalized with strong electron donor−acceptor groups and are of potential interest in second-order nonlinear optics (NLO). Dimeric copper(II) and palladium(II) complexes with L1 and L2 have been prepared, and, starting from these, mononuclear acentric adducts with pyridine as a further ligand have been prepared and characterized. The X-ray structures of three adducts are also reported. The NLO activity of the adducts has been determined by EFISH measurements giving μβ values up to 1500 × 10-48 esu for an incident wavelength of 1.907 μm.

Synthesis, structure, and second-order nonlinear optical properties of copper(II) and palladium(II) acentric complexes with N-salicylidene-N'-aroylhydrazine tridentate ligands.

Tridentate ligands are simple low-cost pincers, easy to synthetize, and able to guarantee stability to the derived complexes. On the other hand, due to its unique mix of structural and optical properties, zinc(II) ion is an excellent candidate to modulate the emission pattern as desired. The present work is an overview of selected articles about zinc(II) complexes showing a tuned fluorescence response with respect to their tridentate ligands. A classification of the tridentate pincers was carried out according to the binding donor atom groups, specifically nitrogen, oxygen, and sulfur donor atoms, and depending on the structure obtained upon coordination. Fluorescence properties of the ligands and the related complexes were compared and discussed both in solution and in the solid state, keeping an eye on possible applications.

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The Role of Zinc(II) Ion in Fluorescence Tuning of Tridentate Pincers: A Review.

Iodofluorination of alkenes and alkynes promoted by iodine and 4-iodotoluene difluoride

We report the synthesis of a luminescent N-salicylidene aniline derivative, N-salicylidene-4-amino-2-methylbenzotriazole (1), and the study of its polymorphism and photophysical properties. Three phases showing yellow (1-Y), orange (1-O), and red (1-R) fluorescence have been isolated and characterized by thermal and single crystal X-ray analysis. The photoluminescence results from excited-state intramolecular proton transfer process and the quantum yield is strongly dependent on polymorphism (Φ1-Y = 0.87, Φ1-O = 0.11, Φ1-R = 0.028). The poorly emitting 1-R can be easily prepared, converted to the bright 1-Y by grinding, and reverted to 1-R through melting and annealing, giving rise to a luminescence on–off mechano-responsive cycle. The different photophysical properties are explained with the variable π-overlap and molecular conformation changes in the three polymorphs, characterized by a very similar crystal packing. By DFT calculations, the absorption properties were explained as dependent on the torsio...

Barbara Panunzi

Papers

Elemental Iodine or Diphenyl Diselenide in the [Bis(trifluoroacetoxy)iodo]benzene‐Mediated Conversion of Alkynes into 1,2‐Diketones

Synthesis, structure, and second-order nonlinear optical properties of copper(II) and palladium(II) acentric complexes with N-salicylidene-N'-aroylhydrazine tridentate ligands.

The Role of Zinc(II) Ion in Fluorescence Tuning of Tridentate Pincers: A Review.

Iodofluorination of alkenes and alkynes promoted by iodine and 4-iodotoluene difluoride

On–Off Mechano-responsive Switching of ESIPT Luminescence in Polymorphic N-Salicylidene-4-amino-2-methylbenzotriazole