Editorial Cite This: J. Org. Chem. 2017, 82, 11667-11668
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Editorial for the Special Issue on Hypervalent Iodine Reagents
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hypervalent iodine reagents are published every year. Starting from 2001, the International Conference on Hypervalent Iodine Chemistry has been regularly convened in Europe or Japan. The continuous development of numerous new hypervalent iodine reagents and the discovery of catalytic applications of organoiodine compounds are the most impressive modern achievements in the field of organoiodine chemistry. The discovery of highly efficient, enantioselective molecular catalysts based on the unique iodine redox chemistry has added a new dimension to the field of hypervalent iodine chemistry and initiated a major surge of research activity. In particular, the design of effective chiral hypervalent iodine catalysts has enabled inherently new oxidative transformations, and high interest in the exploration of these catalysts is expected to continue in the future. This Special Issue of The Journal of Organic Chemistry includes 37 research papers submitted from 13 countries covering key topics of modern hypervalent iodine chemistry. Theoretical aspects of the hypervalent bonding and reactivity are discussed in the manuscript of Lüthi and co-workers. Legault and co-workers have developed a theoretical and experimental approach allowing prediction of the Lewis acidity of cationic iodine(III) species. Several papers are dedicated to the preparation of new hypervalent iodine reagents and development of new synthetic methodologies based on these reagents. In particular, Bolm and co-workers have reported the preparation of sulfoximidoyl-containing hypervalent iodine(III) compounds, 1-sulfoximidoyl-1,2-benziodoxoles, which are potential reagents for transfer of the sulfoximidoyl group to organic substrates. Several research groups (Fujita, Masson, Ishihara, Kita, and Wirth) have described highly enantioselective reactions using new chiral hypervalent iodine reagents. New, highly efficient synthetic protocols for alkynylations (You) and perfluoroalkylations (Studer) utilizing benziodoxolebased reagents have been developed. The majority of the research articles in this Special Issue deal with the development of new synthetic methodologies using common hypervalent iodine reagents and iodonium salts. Hypervalent iodine reagents can be used as efficient oxidants in various oxidative cyclizations, fragmentations, rearrangements, and functionalizations of organic substrates. Several papers describe new approaches to the synthesis of iodine(III) derivatives such as iodonium salts (Hinkle, Olofsson, and Noël) and difluoroiodoarenes (Gilmour). Tsarevsky and co-workers have reported the application of the in situ generated hypervalent iodine(III) (pseudo)halides (e.g., azide, isocyanate, cyanate, and bromide) as initiators for radical polymerization. In conclusion, the papers published in this Special Issue demonstrate increasing research activity in different areas of hypervalent iodine chemistry. Hypervalent iodine reagents and synthetic methodologies involving hypervalent iodine species have become essential tools of modern organic synthesis. We
rganic compounds of iodine in higher oxidation states, which are known under the common name of hypervalent iodine compounds, have emerged as versatile and environmentally benign reagents for organic chemistry.1 Iodine formally belongs to main group elements; however, because of the large atom size, the bonding description in polyvalent iodine compounds differs from the light main-group elements. The π-bonds, present in the compounds of light p-block elements with double and triple bonds, are not observed in the polyvalent iodine compounds. Instead, a different type of bonding occurs due to the overlap of the 5p orbital on the iodine atom with the appropriate orbitals on the two ligands (L) forming a linear L−I−L bond. This molecular orbital description of such a three-center, four-electron (3c−4e) bond was independently developed by G. C. Pimentel and R. E. Rundle in 1951.2 The three-center, four-electron bond is commonly referred to as a “hypervalent bond”.3 Hypervalent bonds are highly polarized and are longer and weaker compared to regular covalent bonds, and the presence of hypervalent bonding explains the special structural features and unparalleled reactivity pattern of polyvalent iodine compounds. In the current literature, the synthetically useful derivatives of polyvalent iodine are generally referred to as “hypervalent iodine reagents”.1 The reactivity pattern of hypervalent iodine reagents is similar to that of the transition-metal derivatives, and the reactions of hypervalent iodine reagents are commonly discussed in terms of oxidative addition, ligand exchange, reductive elimination, and ligand coupling, which are typical of transition-metal chemistry. Exploration and practical utilization of these similarities has already led to the development of new useful methodologies for modern organic synthesis. The first organic hypervalent iodine compound, (dichloroiodo)benzene, was prepared by the German chemist C. Willgerodt in 1886.4 This was rapidly followed by the preparation of many others, including the most common reagents (diacetoxyiodo)benzene and iodosylbenzene5 in 1892, 2-iodoxybenzoic acid (IBX) in 1893,6 and the first examples of diaryliodonium salts reported by C. Hartmann and V. Meyer in 1894.7 These early accomplishments already included the discovery of effective methodology for the modification of hypervalent iodine reagents to accomplish diversification of structure and reactivity.8 Since the beginning of the 21st century, the chemistry of organohypervalent iodine compounds has experienced explosive development. This surging interest in iodine compounds is mainly due to the very useful oxidizing properties of hypervalent iodine reagents, combined with their benign environmental character, commercial availability, and convenient structural modification. Iodine(III) and iodine(V) derivatives are now routinely used in organic synthesis as efficient reagents for various selective oxidative transformations of complex organic molecules. Four books1a−d and over 100 reviews summarizing various aspects of hypervalent iodine chemistry have been published since the year of 2000, and hundreds (if not thousands) of research works utilizing © 2017 American Chemical Society
Special Issue: Hypervalent Iodine Reagents Published: November 17, 2017 11667
DOI: 10.1021/acs.joc.7b02531 J. Org. Chem. 2017, 82, 11667−11668
The Journal of Organic Chemistry
Editorial
anticipate that the inspiring chemistry of hypervalent iodine compounds will continue to attract significant interest and research activity in the future.
Viktor V. Zhdankin, Guest Editor Department of Chemistry and Biochemistry, University of Minnesota Duluth
Kilian Muñiz, Guest Editor
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Institute of Chemical Research of Catalonia (ICIQ) and ICREA
AUTHOR INFORMATION
ORCID
Viktor V. Zhdankin: 0000-0002-0315-8861 Kilian Muñiz: 0000-0002-8109-1762 Notes
Views expressed in this editorial are those of the authors and not necessarily the views of the ACS.
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REFERENCES
(1) For selected books and reviews, see: (a) Hypervalent Iodine Chemistry; Wirth, T., Ed.; Springer-Verlag: Berlin, 2003. (b) Zhdankin, V. V. Hypervalent Iodine Chemistry: Preparation, Structure, and Synthetic Applications of Polyvalent Iodine Compounds; Wiley: Chichester, 2013. (c) Iodine Chemistry And Applications; Kaiho, T., Ed.; John Wiley & Sons, Inc.: Chichester, 2015. (d) Wirth, T., Ed. Hypervalent Iodine Chemistry. Top. Curr. Chem. 2016, 373373.10.1007/978-3-319-337333 (e) Yoshimura, A.; Zhdankin, V. V. Chem. Rev. 2016, 116, 3328− 3435. (2) (a) Pimentel, G. C. J. Chem. Phys. 1951, 19, 446−448. (b) Hach, R. J.; Rundle, R. E. J. Am. Chem. Soc. 1951, 73, 4321−4324. (3) (a) Ramsden, C. A. Chem. Soc. Rev. 1994, 23, 111−118. (b) Chemistry of Hypervalent Compounds; Akiba, K.-y., Ed.; WileyVCH: New York, 1999. (4) Willgerodt, C. J. Prakt. Chem. 18865, 33, 154−160. (5) Willgerodt, C. Ber. Dtsch. Chem. Ges. 1892, 25, 3494−3502. (6) Hartmann, C.; Meyer, V. Ber. Dtsch. Chem. Ges. 1893, 26, 1727− 1732. (7) Hartmann, C.; Meyer, V. Ber. Dtsch. Chem. Ges. 1894, 27, 426− 432. (8) Willgerodt, C. Die Organischen Verbindungen mit Merhrwertigem Jod; Ferdinand Enke: Stuttgart, 1914.
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DOI: 10.1021/acs.joc.7b02531 J. Org. Chem. 2017, 82, 11667−11668
