- Generation of mono- and bis-dioxiranes from 2,3-butanedione
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Biacetyl reacts with oxone to give bis-dioxirane [3,3′-dimethyl-3, 3′-bidioxirane, 3B] and mono-dioxirane [1-(3-methyl-dioxiran-3-yl) ethanone, 3A)]. Bis-dioxirane 3B is formed when two oxygens are incorporated into biacetyl, while mono-dioxirane 3A incorporated only one. A greater stability is observed in 3B compared to 3A, which is attributed to an α-dioxiranyl (anomeric) effect in the former. In contrast, 3A suffers from a destabilizing π-electron withdrawing effect from the adjacent carbonyl group.
- Sawwan, Nahed,Greer, Alexander
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- Uncatalyzed, on water oxygenative cleavage of inert C-N bond with concomitant 8,7-amino shift in 8-aminoquinoline derivatives
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Oxygenative cleavage of an inert CAr-NH2 bond with concomitant 1,2 amine migration in 8-aminoquinoline derivatives is reported in water at room temperature. The reaction is highly atom- and step-economical as both C- and N-containing fragments of the C-N bond cleavage are incorporated into the target molecule and is effected without the need for N-oxide. The reaction is scalable to gram level, and the products are useful as electrophilic partners for coupling reactions, ligands in catalysis and bioactive compounds.
- Botla, Vinayak,Pilli, Navyasree,Malapaka, Chandrasekharam
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supporting information
p. 1735 - 1742
(2019/04/08)
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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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- Palladium-catalyzed ortho-functionalization of azoarenes with aryl acylperoxides
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With the aid of an azo directing group, Pd-catalyzed ortho-sp2 C-H bond activation/functionalization of azoarenes with aryl acyl peroxides has been explored. This transformation provides easy access to regioselectively introducing acyloxyl and aryl groups into azoarenes by simply changing the reaction temperature and solvent. This journal is the Partner Organisations 2014.
- Qian, Cheng,Lin, Dongen,Deng, Yuanfu,Zhang, Xiao-Qi,Jiang, Huanfeng,Miao, Guang,Tang, Xihao,Zeng, Wei
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p. 5866 - 5875
(2014/08/05)
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- HIGH-PURITY ALICYCLIC EPOXY COMPOUND, PROCESS FOR PRODUCING THE SAME, CURABLE EPOXY RESIN COMPOSITION, CURED ARTICLE THEREOF, AND USE
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The present invention provides a high-purity alicyclic epoxy compound in which an alicyclic olefin compound is epoxidized with an aliphatic percarboxylic acid having substantially no water followed by the removal of a solvent to produce an alicyclic epoxy compound represented by the general formula (I) that is in turn subjected to purification by distillation to thereby the high-purity alicyclic epoxy compound wherein the concentration of high-molecular-weight components having an elution time shorter than that of the alicyclic epoxy compound in detection by a GPC analysis is 5.5% or less in terms of the area ratio, the concentration of impurities having a retention time shorter than that of the alicyclic epoxy compound in detection by a GC analysis is 19.5% or less in terms of the area ratio, the concentration of reactive intermediates is 4.5% or less in terms of the area ratio, and a color hue (APHA) is 60 or less; a process of efficiently producing the same by the use of a low-toxicity solvent; a curable resin composition using the same; a cured product; and applications.
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Page/Page column 12
(2010/11/24)
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- Structure-reactivity correlation for reactions of peroxide anion nucleophiles with substituted acyloxybenzenesulfonate bleach activators
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Second-order rate constants are reported for the reaction between a series of esteric bleach activators with different acyl substituents, namely, acetyloxybenzenesulfonate, n-butanoyloxybenzenesulfonate, n-nonanoyloxybenzenesulfonate and isononanoyloxybenzenesulfonate, and a set of peroxide nucleophiles whose basicity ranges from below that of the oxybenzenesulfonate leaving group to above it. The results conform to a Broensted-type relationship with βnuc, 0.42+/-0.01 for acetyloxybenzenesulfonate, very similar to the value of 0.40+/-0.01 for para-nitrophenyl acetate and a range of peroxide nucleophiles. A significantly larger value of βnuc, 0.56+/-0.05 is obtained with n-nonanoyloxybenzenesulfonate. This increase in βnuc is interpreted in terms of steric and polar interactions between the acyl substituent and the attacking nucleophile. The reactivity of n-butanoyloxybenzenesulfonate is similar to that of n-nonanoyloxybenzenesulfonate whilst that of isononanoyloxybenzenesulfonate is less. These results are discussed in terms of the practical consequences for bleach activation and with regard to the mechanism of acyl transfer from esters to peroxides.
- Davies, D. Martin,Foggo, Steven J.,Paradis, Paul M.
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p. 1381 - 1384
(2007/10/03)
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- Detection of Elusive Chloro- and Bromo Substituted Ozonides by Nucleophilic Substitution Reactions
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Ozonolyses of 2,3-dichloro-2-butene (4), 4,5-dichloro-4-octene (9) and 2,3-dibromo-1,4-dichloro-2-butene (12) on polyethylene gave the corresponding ozonides 5,10 and 13a, respectively, which could not be isolated or unequivocally identified. Their identity could be proven, however, via substitution of the chloro- or bromo substituents at the ozonide rings by stabilizing substituents and subsequent isolation of the substituted ozonides 6, 11, 13b and 13c. Ozonolysis of 2,3-diacetoxy-2-butene (14) on polyethylene, in dichloro methane and in pentane gave mixtures of 16 and 17 but not ozonide 6.
- Griesbaum, Karl,Schlindwein, Konrad,Bettinger, Herbert
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p. 307 - 310
(2007/10/03)
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- Ozonolyses of Olefins with Chloro Substituents in Vinylic Positions on Polyethylene
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Ozonolyses of the chloro-substituted 5- and 6-membered cycloolefins 20a, 20b and 30a-c on polyethylene afforded the corresponding chloro-substituted ozonides.The thermal decomposition of these ozonides is described.Ozonolyses of the same olefins in solution and of the acyclic chloro olefins 5 and 8 both on polyethylene and in solution gave no ozonides.
- Griesbaum, Karl,Greinert, Reinhard
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p. 391 - 397
(2007/10/02)
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- Acyloxy-1,2,4-trioxolanes by Dry Ozonolyses of Vinylesters on Polyethylene
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By dry ozonolyses on polyethylene, the vinylic esters 5a-5e afforded the corresponding ozonides 8a-8e, while 5f gave ozonide 8e.Ozonide 8a gave among other products 16 and 17 by thermal decomposition, and 21 by decomposition on silica gel. - Key Words: Acyloxy-1,2,4-trioxolanes / Ozonolysis, dry / Polyethylene / Vinylic esters
- Griesbaum, Karl,Volpp, Willi,Huh, Tae-Seong,Jung, In Chan
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p. 941 - 944
(2007/10/02)
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- Safe diacyl peroxide solution compositions
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A safe peroxide solution composition consisting essentially of a diacyl peroxide having 1-5 carbon atoms in each aliphatic group and an aliphatic hydrocarbon, ketone, ester, ether, or alcohol characterized by a vapor pressure substantially that of the peroxide. Example: Equal parts by weight of diacetyl peroxide and ethyl butyl ketone.
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