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Hypervalent Compounds

A special issue of Molecules (ISSN 1420-3049).

Deadline for manuscript submissions: closed (10 May 2012) | Viewed by 26099

Special Issue Editor


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Guest Editor
Department of Chemistry, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
Interests: main group chemistry; hypervalent compound; fluorescent compound; structural chemistry; organic chemistry

Special Issue Information

Dear Colleagues,

There are several compounds from main group elements that have formally more than eight valence electrons, called hypervalent compounds. Some people suggested the use of the term “hypercoordinate”rather than “hypervalent”. Although the hypervalent compounds were previously believed to be unstable species or reaction intermediates, a variety of hypervalent compounds of phosphorus, sulfur, silicon, iodine, and other main group elements have been synthesized as a stable form to date. Their structure, reactivity, and property have been studied both experimentally and theoretically. In addition to such the fundamental studies, several hypervalent iodine compounds are applied effectively to organic synthesis. This special issue of Molecules will consider any aspect associated with hypervalent compounds.

Dr. Naokazu Kano
Guest Editor

Keywords

  • atrane
  • hypercoordination
  • hypervalency
  • hypervalent compound
  • reaction intermediate
  • ligand coupling
  • main group element
  • octet rule
  • pseudorotation
  • three-center four-electron bond
  • silicon
  • phosphorus
  • sulfur
  • iodine
  • xenon

Published Papers (3 papers)

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Research

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318 KiB  
Communication
IBS-Catalyzed Regioselective Oxidation of Phenols to 1,2-Quinones with Oxone®
by Muhammet Uyanik, Tatsuya Mutsuga and Kazuaki Ishihara
Molecules 2012, 17(7), 8604-8616; https://doi.org/10.3390/molecules17078604 - 18 Jul 2012
Cited by 63 | Viewed by 10352
Abstract
We have developed the first example of hypervalent iodine(V)-catalyzed regioselective oxidation of phenols to o-quinones. Various phenols could be oxidized to the corresponding o-quinones in good to excellent yields using catalytic amounts of sodium salts of 2-iodobenzenesulfonic acids (pre-IBSes) [...] Read more.
We have developed the first example of hypervalent iodine(V)-catalyzed regioselective oxidation of phenols to o-quinones. Various phenols could be oxidized to the corresponding o-quinones in good to excellent yields using catalytic amounts of sodium salts of 2-iodobenzenesulfonic acids (pre-IBSes) and stoichiometric amounts of Oxone® as a co-oxidant under mild conditions. The reaction rate of IBS-catalyzed oxidation under nonaqueous conditions was further accelerated in the presence of an inorganic base such as potassium carbonate (K2CO3), a phase transfer catalyst such as tetrabutylammonium hydrogen sulfate (nBu4NHSO4), and a dehydrating agent such as anhydrous sodium sulfate (Na2SO4). Full article
(This article belongs to the Special Issue Hypervalent Compounds)
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247 KiB  
Article
Reaction of Iodonium Ylides of 1,3-Dicarbonyl Compounds with HF Reagents
by Keisuke Gondo and Tsugio Kitamura
Molecules 2012, 17(6), 6625-6632; https://doi.org/10.3390/molecules17066625 - 31 May 2012
Cited by 18 | Viewed by 6679
Abstract
Reaction of dibenzoylmethane with (diacetoxyiodo)benzene in the presence of KOH in MeCN quantitatively gave the corresponding iodonium ylide, which was treated with a HF reagent to afford the corresponding 2-fluorinated dibenzoylmethane in 14–50% yields. The similar reaction of the iodonium ylides obtained from [...] Read more.
Reaction of dibenzoylmethane with (diacetoxyiodo)benzene in the presence of KOH in MeCN quantitatively gave the corresponding iodonium ylide, which was treated with a HF reagent to afford the corresponding 2-fluorinated dibenzoylmethane in 14–50% yields. The similar reaction of the iodonium ylides obtained from 1-phenylbutan-1,3-dione, ethyl benzoylacetate, and ethyl p-nitrobenzoylacetate with TEA·3HF gave the corresponding fluorinated products in 17–34% yields. It is suggested that the fluorinated products were formed through the C-protonation of the ylide, followed by displacement with fluoride ion. The same reaction of the iodonium ylide of dibenzoylmethane with concentrated HCl gave the corresponding chlorinated product in 45% yield. Full article
(This article belongs to the Special Issue Hypervalent Compounds)
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Review

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482 KiB  
Review
Hypervalent Nonbonded Interactions of a Divalent Sulfur Atom. Implications in Protein Architecture and the Functions
by Michio Iwaoka and Noriyoshi Isozumi
Molecules 2012, 17(6), 7266-7283; https://doi.org/10.3390/molecules17067266 - 13 Jun 2012
Cited by 117 | Viewed by 7923
Abstract
In organic molecules a divalent sulfur atom sometimes adopts weak coordination to a proximate heteroatom (X). Such hypervalent nonbonded S···X interactions can control the molecular structure and chemical reactivity of organic molecules, as well as their assembly and packing in the solid state. [...] Read more.
In organic molecules a divalent sulfur atom sometimes adopts weak coordination to a proximate heteroatom (X). Such hypervalent nonbonded S···X interactions can control the molecular structure and chemical reactivity of organic molecules, as well as their assembly and packing in the solid state. In the last decade, similar hypervalent interactions have been demonstrated by statistical database analysis to be present in protein structures. In this review, weak interactions between a divalent sulfur atom and an oxygen or nitrogen atom in proteins are highlighted with several examples. S···O interactions in proteins showed obviously different structural features from those in organic molecules (i.e., πO → σS* versus nO → σS* directionality). The difference was ascribed to the HOMO of the amide group, which expands in the vertical direction (πO) rather than in the plane (nO). S···X interactions in four model proteins, phospholipase A2 (PLA2), ribonuclease A (RNase A), insulin, and lysozyme, have also been analyzed. The results suggested that S···X interactions would be important factors that control not only the three-dimensional structure of proteins but also their functions to some extent. Thus, S···X interactions will be useful tools for protein engineering and the ligand design. Full article
(This article belongs to the Special Issue Hypervalent Compounds)
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