- Preparation and Synthetic Applicability of Imidazole-Containing Cyclic Iodonium Salts
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A novel approach to the preparation of imidazole-substituted cyclic iodonium salts has been developed via the oxidative cyclization of 1-phenyl-5-iodoimidazole using a cheap and available Oxone/H2SO4 oxidative system. The structure of the new polycyclic heteroarenes has been confirmed by single-crystal X-ray diffractometry, revealing the characteristic structure features for cyclic iodonium salts. The newly produced imidazole-flanked cyclic iodonium compounds were found to readily engage in a heterocyclization reaction with elemental sulfur, affording benzo[5,1-b]imidazothiazoles in good yields.
- Antonkin, Nikita S.,Vlasenko, Yulia A.,Yoshimura, Akira,Smirnov, Vladimir I.,Borodina, Tatyana N.,Zhdankin, Viktor V.,Yusubov, Mekhman S.,Shafir, Alexandr,Postnikov, Pavel S.
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p. 7163 - 7178
(2021/05/29)
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- The Role of Iodanyl Radicals as Critical Chain Carriers in Aerobic Hypervalent Iodine Chemistry
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Selective O2 utilization remains a substantial challenge in synthetic chemistry. Biological small-molecule oxidation reactions often utilize aerobically generated high-valent catalyst intermediates to effect substrate oxidation. Available synthetic methods for aerobic oxidation catalysis are largely limited to substrate functionalization chemistry by low-valent catalyst intermediates (i.e., aerobically generated Pd(II) intermediates). Motivated by the need for new chemical platforms for aerobic oxidation catalysis, we recently developed aerobic hypervalent iodine chemistry. Here, we report that in contrast to the canonical two-electron oxidation mechanisms for the oxidation of organoiodides, the developed aerobic hypervalent iodine chemistry proceeds via a radical chain mechanism initiated by the addition of aerobically generated acetoxy radicals to aryl iodides. Despite the radical chain mechanism, aerobic hypervalent iodine chemistry displays substrate tolerance similar to that observed with traditional terminal oxidants, such as peracids. We anticipate that these insights will enable new sustainable oxidation chemistry via hypervalent iodine intermediates. O2 is routinely utilized in biological catalysis to generate high-valent catalyst intermediates that engage in substrate oxidation chemistry. Analogous synthetic chemistry via aerobically generated high-valent intermediates would enable new sustainable synthetic methods but is largely unknown because of the challenges in selective O2 utilization. We have developed aerobic hypervalent iodine chemistry as a platform for coupling O2 reduction with a diverse set of substrate functionalization mechanisms. Many of the synthetic applications of hypervalent iodine reagents rely on selective two-electron oxidation-reduction chemistry. Here, we report that one-electron oxidation reactions pathways via iodanyl radical intermediates are critical in aerobic hypervalent iodine chemistry. The new appreciation for the critical role that iodanyl radicals can play in the synthesis of hypervalent iodine compounds will provide new opportunities in sustainable oxidation catalysis. Aerobic hypervalent iodine chemistry provides a strategy for coupling the one-electron chemistry of O2 with two-electron processes typical of organic synthesis. We show that in contrast to the canonical two-electron oxidation of aryl iodides, aerobic synthesis proceeds by a radical chain process initiated by the addition of aerobically generated acetoxy radicals to aryliodides to generate iodanyl radicals. Robustness analysis reveals that the developed aerobic oxidation chemistry displays substrate tolerance similar to that observed in peracid-based methods and thus holds promise as a sustainable synthetic method.
- Hyun, Sung-Min,Yuan, Mingbin,Maity, Asim,Gutierrez, Osvaldo,Powers, David C.
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supporting information
p. 2388 - 2404
(2019/09/12)
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- Synthesis of O -Aroyl- N, N -dimethylhydroxylamines through Hypervalent Iodine-Mediated Amination of Carboxylic Acids with N, N -Dimethylformamide
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An efficient protocol for the synthesis of O -aroyl- N, N -dimethylhydroxylamines, which are important electrophilic amination reagents, is described. The reaction between carboxylic acids and N, N -dimethylformamide is mediated by hypervalent iodine and
- Zhang, Chuancheng,Yue, Qiang,Xiao, Zhen,Wang, Xianglan,Zhang, Qian,Li, Dong
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supporting information
p. 4303 - 4308
(2017/09/13)
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- NH-Heterocyclic Aryliodonium Salts and their Selective Conversion into N1-Aryl-5-iodoimidazoles
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The synthesis of N-arylimidazoles substituted at the sterically encumbered 5-position is a challenge for modern synthetic approaches. A new family of imidazolyl aryliodonium salts is reported, which serve as a stepping stone on the way to selective formation of N1-aryl-5-iodoimidazoles. Iodine acts as a “universal” placeholder poised for replacement by aryl substituents. These new λ3-iodanes are produced by treating the NH-imidazole with ArI(OAc)2, and are converted to N1-aryl-5-iodoimidazoles by a selective copper-catalyzed aryl migration. The method tolerates a variety of aryl fragments and is also applicable to substituted imidazoles.
- Wu, Yichen,Izquierdo, Susana,Vidossich, Pietro,Lledós, Agustí,Shafir, Alexandr
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supporting information
p. 7152 - 7156
(2016/07/06)
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- Tandem catalytic C(sp3)-H amination/sila-sonogashira-hagihara coupling reactions with iodine reagents
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A new tandem C-N and C-C bond-forming reaction has been achieved through RhII/Pd0 catalysis. The sequence first involves an iodine(III) oxidant, then the in situ generated iodine(I) by-product is used as a coupling partner. The overall process demonstrates the synthetic value of iodoarenes produced in trivalent iodine reagent mediated oxidations. I(003) is a double agent: A tandem C-N and C-C bond-forming reaction has been achieved through RhII/Pd0 catalysis. The sequence first involves an iodine(III) oxidant, then the in situ generated iodine(I) by-product is used as a coupling partner. The overall process affords complex building blocks with high yields, and demonstrates the synthetic value of iodoarenes produced in trivalent iodine reagent mediated oxidations.
- Buendia, Julien,Darses, Benjamin,Dauban, Philippe
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supporting information
p. 5697 - 5701
(2015/06/16)
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- Synthesis and reactivity of aryl(alkynyl)iodonium salts
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The first practical, yet simple, preparation of aryl(alkynyl)iodonium trifluoroacetate salts is described. The generic nature of this synthetic method has allowed the production of a range of aryl(alkynyl)iodonium trifluoroacetate salts with independent variation of both the alkynyl and aryliodo groups in yields of 30-85 %. Application of these new reagents to the synthesis of a series of 2-arylfuro[3,2-c]pyridines (40-64 %) highlights the potential of this class of materials as precursors to bioactive heterocyclic structures. These experiments have also demonstrated that, in this case, the effect of the aryliodo group on the reaction is negligible.
- Dixon, Luke I.,Carroll, Michael A.,Gregson, Thomas J.,Ellames, George J.,Harrington, Ross W.,Clegg, William
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supporting information
p. 2334 - 2345
(2013/05/21)
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- Approach to the synthesis of indoline derivatives from diaryliodonium salts
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An effective method of constructing the indoline moiety via intramolecular nucleophilic ring closure of a diaryliodonium salt is described. Diacetoxyiodoarene compounds (1a-1e) were converted into intermediate Koser's reagent and coupled with arylstannanes (7-10) to form diaryliodonium salts (11a-14e). Indoline compounds with different N-protecting groups, 15, 16, 17, and 18, were synthesized in higher yields by treating salts (11a-14e) with Cs2CO3 and TEMPO. Regardless of the electronic environment of five para-substituted iodoarenes and the natures of four N-protected arylstannane groups, the conversion proceeded well to afford corresponding indolines in yields of 72-84 and 70-84%, respectively.
- Landge, Kamalkishor P.,Jang, Keun Sam,Lee, Sang Yeul,Chi, Dae Yoon
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experimental part
p. 5705 - 5713
(2012/09/07)
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- Direct arylation of benzoxazole C-H bonds with iodobenzene diacetates
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A Pd (OAc)2-catalyzed direct arylation of benzoxazole C-H bonds has been achieved with iodobenzene diacetates as the arylation reagent in moderate to good yields. The procedure tolerates a series of functional groups, such as methoxy, nitro, cyano, chloro, and bromo groups.
- Yu, Peng,Zhang, Guangyou,Chen, Fan,Cheng, Jiang
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supporting information; experimental part
p. 4588 - 4590
(2012/09/22)
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- 4-ARYLOXYQUINOLIN-2(1H)-ONES AS MTOR KINASE AND PI3 KINASE INHIBITORS, FOR USE AS ANTI-CANCER AGENTS
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4-aryloxyquinolin-2(1H)-ones as mtor kinase and PI3 kinase inhibitors, for use as anti-cancer agents. Compounds of the formula I and pharmaceutically acceptable salts thereof, wherein A, B, R1, R2, R3, R4, R5, R6, and R7 are defined as set forth herein are disclosed. Also disclosed are pharmaceutical compositions comprising the compounds of the invention and a pharmaceutically acceptable carrier, methods of making the compounds of the invention and methods of using the compounds for inhibiting mTOR and PI3 kinases and for treating cancers.
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Page/Page column 60
(2010/04/06)
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- New and direct approach to hypervalent iodine compounds from arenes and iodine. straightforward synthesis of (diacetoxyiodo)arenes and diaryliodonium salts using potassium μ-peroxo-hexaoxodisulfate
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The reaction of arenes with elemental iodine, acetic acid, and potassium μ-peroxo-hexaoxodisulfate (K2S2O8) in the presence of concentrated sulfuric acid, efficiently generated the corresponding (diacetoxyiodo)arenes in good yields. Diaryliodonium triflates were directly synthesized by reaction of arenes with elemental iodine in good yields by using K2S2O8, AcOH, and TfOH. Diaryliodonium tosylates were also prepared from arenes and elemental iodine by using K 2S2O8, AcOH, H2SO4, and TsOH. The procedure involved mild conditions and a straightforward one-pot synthesis.
- Hossain, Md. Delwar,Kitamura, Tsugio
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experimental part
p. 2213 - 2219
(2009/08/08)
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- Direct, easy, and scalable preparation of (diacetoxyiodo)arenes from arenes using potassium peroxodisulfate as the oxidant
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The reaction of arenes with potassium peroxodisulfate, elemental iodine, and acetic acid in the presence of concd sulfuric acid, efficiently generates the corresponding (diacetoxyiodo)arenes in good yields, providing an easy, safe, and effective method for preparing (diacetoxyiodo)arenes from arenes and iodine.
- Hossain, Md. Delwar,Kitamura, Tsugio
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p. 7889 - 7891
(2007/10/03)
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- Unexpected, drastic effect of triflic acid on oxidative diacetoxylation of iodoarenes by sodium perborate. A facile and efficient one-pot synthesis of (diacetoxyiodo) arenes
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An easy, safe, and effective method for preparing (diacetoxyiodo)arenes from iodoarenes is presented. Addition of trifluoromethanesulfonic acid (triflic acid) as a promoter causes a drastic increase in the yield of (diacetoxyiodo)arenes in the reaction of iodoarenes with sodium perborate. The reaction of the iodoarenes with sodium perborate in acetic acid in the presence of triflic acid at 40-45 °C efficiently generates the corresponding (diacetoxyiodo)arenes in high yields within short time.
- Hossain, Md. Delwar,Kitamura, Tsugio
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p. 6984 - 6986
(2007/10/03)
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- Alternative, easy preparation of (diacetoxyiodo)arenes from iodoarenes using potassium peroxodisulfate as the oxidant
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An easy, safe and effective method for preparing (diacetoxyiodo)arenes [ArI(OAc)2], from iodoarenes is presented in this paper, using potassium peroxodisulfate as the oxidant. This procedure avoids the use of high temperature and severe reaction conditions. The reaction of the iodoarenes with potassium peroxodisulfate in acetic acid in the presence of concentrated sulfuric acid or trifluoromethane sulfonic acid at room temperature, efficiently generates the corresponding (diacetoxyiodo)arenes in high yield in a short reaction time. Georg Thieme Verlag Stuttgart.
- Hossain, Md. Delwar,Kitamura, Tsugio
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p. 1932 - 1934
(2007/10/03)
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- Syntheses of (diacetoxyiodo)arenes or iodylarenes from iodoarenes, with sodium periodate as the oxidant
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Easy, safe, and effective novel methods for preparing either (diacetoxyiodo)-(arenes, ArI(OAc)2, or iodylarenes, ArIO2, from the corresponding iodoarenes, ArI, using sodium periodate as the oxidant are presented in this paper. In order to obtain 2- and 4-iodylbenzoic acids, the respective sodium salts of 2- and 4-iodobenzoic acids should be used as the starting substrates, because mixtures containing the corresponding iodosyl derivatives as the main products along with the intended iodyl compounds are produced from the free parent acids.
- Kazmierczak, Pawel,Skulski, Lech,Kraszkiewicz, Lukasz
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p. 881 - 891
(2007/10/03)
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- Reactivity of arenes in substitution and additiopn reactions
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The reactivity of arenes with 4-methylquinoline (substitution) as a typical heteroaromatic base and phenyl vinyl sulfone (addition) as a typical activated olefin has been studied under thermal and irradiation conditions.The results suggest that electron-withdrawing groups on the aromatic ring in arenes are detrimental to reactions.The crystal structures of arenes 10 and 1e are reported.
- Togo, Hideo,Taguchi, Rie,Yamaguchi, Kentaro,Yoikoyama, Masataka
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p. 2135 - 2140
(2007/10/02)
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- FURTHER FUNCTIONAL GROUP OXIDATIONS USING SODIUM PERBORATE
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Sodium perborate in acetic acid is an effective reagent for the oxidation of aromatic aldehydes to carboxylic acids, iodoarenes to (diacetoxyiodo)arenes, azines to N-oxides, and various types of sulfur heterocycles to S,S-dioxides.Nitriles are unaffected by the reagent in acetic acid, but undergo smooth hydration to amides when aqueous methanol is employed as solvent.
- McKillop, Alexander,Kemp, Duncan
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p. 3299 - 3306
(2007/10/02)
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