- REACTIONS OF CHLORINE DIOXIDE IN DICHLOROMETHANE I. FORMATION OF RADICAL CATIONS IN ACID MEDIA
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Chlorine dioxide oxidises electron rich organic compounds to the corresponding radical cations in dichloromethane/TFA medium.In a different experimental set up using alkaline biphasic solvent system, its utility as hydrogen abstractor has been capitalized in the preparation of diazodiphenyl methane in good yield.
- Handoo, Kishan L.,Handoo, S. K.,Gadru, Kanchan,Kaul, Anju
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- 1,1-Hydroboration and a Borane Adduct of Diphenyldiazomethane: A Potential Prelude to FLP-N2 Chemistry
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Diphenyldiazomethane reacts with HB(C6F5)2 and B(C6F5)3, resulting in 1,1-hydroboration and adduct formation, respectively. The hydroboration proceeds via a concerted reaction involving ini
- Tang, Connie,Liang, Quiming,Jupp, Andrew R.,Johnstone, Timothy C.,Neu, Rebecca C.,Song, Datong,Grimme, Stefan,Stephan, Douglas W.
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Read Online
- Hydrogen bonding switches the spin state of diphenylcarbene from triplet to singlet
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Spin specificity is one of the most important properties of carbenes in their reactions. Alcohols are typically used to probe the reactive spin states of carbenes: O-H insertions are assumed to be characteristic of singlet states, whereas C-H insertions a
- Costa, Paolo,Sander, Wolfram
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Read Online
- All-Carbon Tetrasubstituted Olefins Synthesis from Diazo Compounds and Iodonium Ylides under Blue LED Irradiation
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A route for the construction of all-carbon tetra-substituted olefins through visible-light promoted coupling of diazo compounds with iodonium ylides was developed. A wide range of all-carbon tetra-substituted olefins was obtained in moderate to good yields. The synthetic values of the current method were further approved by the synthesis of natural isolates modified alkenes and the successful transformation of final olefins into important heterocycles. (Figure presented.).
- Zhao, Yan-Rui,Li, Lei,Xu, Guo-Yong,Xuan, Jun
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p. 506 - 511
(2021/12/08)
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- Photochemical Carbene Transfer Reactions of Aryl/Aryl Diazoalkanes—Experiment and Theory**
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Controlling the reactivity of carbene intermediates is a key parameter in the development of selective carbene transfer reactions and is usually achieved by metal complexes via singlet metal-carbene intermediates. In this combined experimental and computational studies, we show that the reactivity of free diaryl carbenes can be controlled by the electronic properties of the substituents without the need of external additives. The introduction of electron-donating and -withdrawing groups results in a significant perturbation of singlet triplet energy splitting of the diaryl carbene intermediate and of activation energies of consecutive carbene transfer reactions. This strategy now overcomes a long-standing paradigm in the reactivity of diaryl carbenes and allows the realization of highly chemoselective carbene transfer reactions with alkynes. We could show that free diaryl carbenes can be readily accessed via photolysis of the corresponding diazo compounds and that these carbenes can undergo highly chemoselective cyclopropenation, cascade, or C?H functionalization reactions. Experimental and theoretical mechanistic analyses confirm the participation of different carbene spin states and rationalize for the observed reactivity.
- Jana, Sripati,Pei, Chao,Empel, Claire,Koenigs, Rene M.
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p. 13271 - 13279
(2021/05/10)
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- Oxime Ether Synthesis through O-H Functionalization of Oximes with Diazo Esters under Blue LED Irradiation
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A green and sustainable oxime ether formation method via the visible-light-promoted O-H functionalization of oximes with diazo esters is described. The reaction occurs under very mild conditions (catalyst- and additive-free) with a high yield and a high functional group tolerance. When the reaction was performed with a cyclic ether as the solvent (e.g., THF, 1,4-dioxane, tetrahydropyran, ect.), an interesting photochemical three-component reaction product was obtained in good yields.
- Li, Qian,Cai, Bao-Gui,Li, Lei,Xuan, Jun
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p. 6951 - 6955
(2021/09/02)
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- Copper-Mediated Cross-Coupling of Diazo Compounds with Sulfinates
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A copper-mediated cross-coupling reaction between a diazo compound and a sodium alkane(arene)sulfinate gives a sulfone as the product. This reaction proceeds under mild conditions and features excellent functional group compatibility. A wide range of sodium alkane(arene)sulfinates were successfully applied in this chemistry. Mechanistic studies revealed that the overall reaction efficiency of the sulfinates was in line with their nucleophilicity in this reaction.
- Wang, Qian,Liu, An,Wang, Yan,Ni, Chuanfa,Hu, Jinbo
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p. 6919 - 6924
(2021/09/11)
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- Silver-Catalyzed N-H Functionalization of Aryl/Aryl Diazoalkanes with Anilines
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Herein, we report on the N-H functionalization reaction of primary and secondary anilines with diaryldiazoalkanes using simple AgPF6 as catalyst. We demonstrated broad applicability in the reaction of diaryldiazoalkanes with different anilines (31 examples, up to 97% yield). Furthermore, we propose a possible reaction mechanism for the N-H functionalization.
- He, Feifei,Empel, Claire,Koenigs, Rene M.
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p. 6719 - 6723
(2021/09/13)
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- Dehalogenative Cross-Coupling of gem-Difluoroalkenes with Alkyl Halides via a Silyl Radical-Mediated Process
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Herein, we describe a convenient general protocol for monofluoroalkenylation reactions of alkyl bromides involving cooperative visible-light photoredox catalysis and halogen abstraction. Mechanistic experiments showed that the products were generated by selective cross-coupling of aliphatic radicals with fluoroalkenyl radicals. Silyl radical-mediated halogen abstraction enabled the protocol to be used for the monofluoroalkenylation of a broad range of alkyl and heteroaryl halides. The protocol could be carried out on a gram scale and was applied to cholesterol, indicating its utility for late-stage monofluoroalkenylation reactions.
- Tian, Hao,Yang, Shaoxiang,Wang, Xiaochen,Xu, Wentao,Liu, Yuxiu,Li, Yongqiang,Wang, Qingmin
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p. 12772 - 12782
(2021/09/13)
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- Copper-Catalyzed Oxidation of Hydrazones to Diazo Compounds Using Oxygen as the Terminal Oxidant
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A mild method for accessing diazo compounds via aerobic oxidation of hydrazones is described. This catalytic transformation employs a Cu(OAc)2/pyridine catalyst and molecular oxygen from ambient air as the terminal oxidant, generating water as the sole byproduct and affording the desired diazo compounds within minutes at room temperature. A broad array of electronically diverse aryldiazo esters, ketones, and amides can be accessed. Pyridine dramatically enhances the rate of the reaction by solubilizing the copper catalyst and serving as the Br?nsted base in the turnover-limiting proton-coupled oxidation of hydrazone by copper(II). Insights gained from mechanistic studies led to expansion of the scope of this method to include diaryl hydrazones, delivering diaryl diazomethane derivatives, which cannot be accessed via established diazo transfer methods. The products of this method may be employed in rhodium carbene catalysis without isolation of the diazo intermediate to afford cyclopropane products in good yield with high enantioselectivity.
- Liu, Wenbin,Twilton, Jack,Wei, Bo,Lee, Maizie,Hopkins, Melissa N.,Bacsa, John,Stahl, Shannon S.,Davies, Huw M. L.
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p. 2676 - 2683
(2021/03/03)
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- Allene C(sp2)-H Activation and Alkenylation Catalyzed by Palladium
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The selective transition-metal-mediated activation of C(sp2)-H bonds of allenes is a formidable challenge because of the competitive, intrinsic reactivity of cumulated double bonds. Herein, we report a Pd-catalyzed C-H alkenylation of electronically unbiased allenes, affording penta-1,2,4-triene products in up to 94% yield. A picolinamide directing group enables the formation of putative allenyl-palladacycles, which subsequently participate in a turnover-limiting Heck-type reaction with electron-deficient alkene coupling partners. This mechanistic proposal is consistent with experimental and computational investigations. Additionally, we report for the first time the use of picolinamide N,O-acetals as readily removable auxiliaries for C-H activation reactions, allowing the efficient alkenylation of allenyl carbinol derivatives. Successful removal of the directing groups without affecting the reactive penta-1,2,4-triene substructure of the products is demonstrated.
- Aouane, Fran?oise A.,Baik, Mu-Hyun,Carreira, Erick M.,Schreib, Benedikt S.,Son, Mina
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supporting information
p. 21705 - 21712
(2022/01/03)
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- Photoelimination of Nitrogen from Diazoalkanes: Involvement of Higher Excited Singlet States in the Carbene Formation
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Although diazoalkanes are important carbene precursors in organic synthesis, a comprehensive mechanism of photochemical formation of carbenes from diazoalkanes has not been proposed. Synergies of experiments and computations demonstrate the involvement of higher excited singlet states in the photochemistry of diazoalkanes. In all investigated diazoalkanes, excitation to S1 results in nonreactive internal conversion to S0. On the contrary, excitation to higher-lying singlet states (Sn, n > 1) drives the reaction toward a different segment of the S1/S0 conical intersection seam and results in nitrogen elimination and formation of carbenes.
- Pite?a, Tomislav,Ale?kovi?, Marija,Becker, Kristin,Basari?, Nikola,Do?li?, Nada
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p. 9718 - 9724
(2020/07/02)
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- Direct Observation of Aggregation-Induced Emission Mechanism
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The mechanism of aggregation-induced emission, which overcomes the common aggregation-caused quenching problem in organic optoelectronics, is revealed by monitoring the real time structural evolution and dynamics of electronic excited state with frequency and polarization resolved ultrafast UV/IR spectroscopy and theoretical calculations. The formation of Woodward–Hoffmann cyclic intermediates upon ultraviolet excitation is observed in dilute solutions of tetraphenylethylene and its derivatives but not in their respective solid. The ultrafast cyclization provides an efficient nonradiative relaxation pathway through crossing a conical intersection. Without such a reaction mechanism, the electronic excitation is preserved in the molecular solids and the molecule fluoresces efficiently, aided by the very slow intermolecular charge and energy transfers due to the well separated molecular packing arrangement. The mechanisms can be general for tuning the properties of chromophores in different phases for various important applications.
- Corminboeuf, Clémence,Guan, Jianxin,Han, Han,Lin, Kun-Han,Liu, Jitian,Peng, Jie,Prlj, Antonio,Wei, Rong,Yu, Zhihao,Zhao, Dahui,Zheng, Junrong
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p. 14903 - 14909
(2020/07/04)
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- Precise Preparation of a High-Purity Key Intermediate of Tazobactam
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In situ IR was used to precisely prepare high-purity diphenylmethyl 6α-bromopenicillanate 8, a key intermediate of tazobactam. 8 was obtained when 6α-bromopenicillanic acid 2 reacted with diphenyldiazomethane (DDM). 2 is unstable and must therefore react
- Zhou, Yanan,Wu, Chengjun,Ma, Hongzhi,Chen, Jianchao,Sun, Tiemin
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p. 2898 - 2905
(2020/12/22)
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- Organocatalytic Nucleophilic Substitution Reaction of gem-Difluoroalkenes with Ketene Silyl Acetals
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An organocatalytic nucleophilic substitution reaction of gem-difluoroalkenes with ketene silyl acetals was developed. Phosphazene P4-tBu effectively catalyzed the reaction under mild conditions to provide monofluoroalkenes possessing an alkoxycarbonylmethyl group in high yields with high Z selectivities.
- Kondoh, Azusa,Koda, Kazumi,Terada, Masahiro
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p. 2277 - 2280
(2019/03/26)
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- Direct α-Monofluoroalkenylation of Heteroatomic Alkanes via a Combination of Photoredox Catalysis and Hydrogen-Atom-Transfer Catalysis
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In this study, a new C(sp3)-H monofluoroalkenylation reaction involving cooperative visible-light photoredox catalysis and hydrogen-atom-transfer catalysis to afford products generated by selective hydrogen abstraction and radical-radical cross-coupling was described. This mild, efficient reaction shows high regioselectivity for the α-carbon atoms of amines, ethers, and thioethers and thus allows the preparation of monofluoroalkenes bearing various substituents. The reaction was applied to two bioactive molecules, indicating its utility for late-stage monofluoroalkenylation of compounds with inert C(sp3)-H bonds.
- Tian, Hao,Xia, Qing,Wang, Qiang,Dong, Jianyang,Liu, Yuxiu,Wang, Qingmin
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p. 4585 - 4589
(2019/06/17)
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- Trifluoromethylation and Monofluoroalkenylation of Alkenes through Radical–Radical Cross-Coupling
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The first visible-light-induced trifluoromethylation and monofluoroalkenylation of simple alkenes via a challenging radical–radical cross-coupling step was achieved. This method provided a mild, step-economical and redox-neutral route to privileged two different fluorinated difunctionalized allyl compounds. The utility of this method is illustrated by late-stage modification of medically important molecules.
- Wang, Qiang,Qu, Yi,Tian, Hao,Liu, Yuxiu,Song, Hongjian,Wang, Qingmin
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p. 8686 - 8690
(2019/06/17)
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- 2,2-diphenylcyclopropyl compound and synthesis method thereof
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The present invention provides a 2,2-diphenylcyclopropyl compound, which has a chemical name 2,2-diphenyl methyl cyclopropanecarboxylate compound, wherein the structure formula is defined in the specification, and the group R in the structure formula represents C1-C4 short-chain alkane, cycloalkane, halogenated alkane or halogenated cycloalkane. The present invention further provides a synthesis method of the 2,2-diphenylcyclopropyl compound, wherein the system method comprises: synthesizing Benzophenone hydrazone, synthesizing diphenyldiazomethane, and synthesizing the target product. According to the present invention, the three-membered ring of the 2,2-diphenyl methyl cyclopropanecarboxylate compound contains a chiral center, which can be used as a chiral precursor to introduce the chiral carbon atom into the reaction product so as to provide more possibility for the development of active compounds; and the synthesis method is simple, easy to operate, and suitable for industrial production.
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- Diastereodivergent synthesis of cyclopropanes: Via on-water [2 + 1] annulations of diazo compounds with electron-deficient alkenes
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A highly efficient cyclopropanation of diazo compounds and electron-deficient alkenes under metal- and catalyst-free conditions was developed. The use of water as the sole solvent dramatically increased the efficiency of the reaction. This on-water synthe
- Li, Qing-Zhu,Zhang, Xiang,Xie, Ke,Dai, Qing-Song,Zeng, Rong,Liu, Yan-Qing,Jia, Zhi-Qiang,Feng, Xin,Li, Jun-Long
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supporting information
p. 2375 - 2379
(2019/05/17)
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- Carbidopa and L-Dopa Prodrugs and Methods of Use
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The present disclosure relates to (a) carbidopa prodrugs, (b) pharmaceutical combinations and compositions comprising a carbidopa prodrug and/or an L-dopa prodrug, and (c) methods of treating Parkinson's disease and associated conditions comprising admini
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Paragraph 0398; 0402
(2019/08/02)
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- Efficient synthesis of ferrocifens and other ferrocenyl-substituted ethylenes: Via a 'sulfur approach'
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Stable and non-odorous alkyl ferrocenyl thioketones react with bis(4-methoxyphenyl)diazomethane according to the 'two-fold extrusion' reaction principles, and tetrasubstituted ethylenes obtained thereby can be demethylated to give (Fc,2OH)-ferrocifens in good yields. The method offers an alternative approach to this class of medically relevant compounds. A similar protocol with alkyl ferrocenyl thioketones and selected diaryldiazomethanes leads to ferrocenyl-substituted ethylenes including dibenzofulvenes. These products are of potential interest for electrochemical and photophysical studies.
- Mlostoń, Grzegorz,Hamera-Fa?dyga, Róza,Celeda, Ma?gorzata,Heimgartner, Heinz
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p. 4350 - 4356
(2018/06/21)
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- Targeted probes of cellular physiology
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Biosensor comprising an activatable acceptor fluorogen linked via a linker to a donor which transfers energy to the fluorogen on detecting an analyte wherein the fluorogen component reacts and a 100 fold increase in intensity results when the fluorogen interacts non-covalently with an activator e.g. fluorogen activator peptide.
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Page/Page column 55
(2018/06/25)
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- Improved synthesis of YT-14, a potent antibiotic to multidrug-resistant strains
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A new practical synthetic approach produced clinical drug candidate YT-14, improving the overall yield from 1.3% to 13.8%. Compared with the previous route, the new route is two steps shorter and all of the steps involve purifications without column chrom
- Wei, Jianhai,Kong, Deyu,Wang, Lei,Zhang, Yinyong,Hu, Wenhao,Yang, Yushe
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p. 354 - 360
(2018/08/21)
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- Continuous Flow Synthesis and Purification of Aryldiazomethanes through Hydrazone Fragmentation
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Electron-rich diazo compounds, such as aryldiazomethanes, are powerful reagents for the synthesis of complex structures, but the risks associated with their toxicity and instability often limit their use. Flow chemistry techniques make these issues avoidable, as the hazardous intermediate can be used as it is produced, avoiding accumulation and handling. Unfortunately, the produced stream is often contaminated with other reagents and by-products, making it incompatible with many applications, especially in catalysis. Herein is reported a metal-free continuous flow method for the production of aryldiazomethane solutions in a non-coordinating solvent from easily prepared, bench-stable sulfonylhydrazones. All by-products are removed by an in-line aqueous wash, leaving a clean, base-free diazo stream. Three successful sensitive metal-catalyzed transformations demonstrated the value of the method.
- Lévesque, éric,Laporte, Simon T.,Charette, André B.
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p. 837 - 841
(2017/01/14)
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- Activation of the B?F Bond by Diphenylcarbene: A Reversible 1,2-Fluorine Migration between Boron and Carbon
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Experiments in low-temperature matrices reveal that triplet diphenylcarbene inserts into the very strong B?F bond of BF3in a two-step reaction. The first step is the formation of a strongly bound Lewis acid–base complex between the singlet stat
- Costa, Paolo,Mieres-Perez, Joel,?zkan, Nesli,Sander, Wolfram
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p. 1760 - 1764
(2017/02/05)
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- Palladium-Catalyzed Fluoroarylation of gem-Difluoroalkenes
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A Pd-catalyzed fluoroarylation of gem-difluoroalkenes with aryl halides is reported. By taking advantage of the in situ generated α-CF3-benzylsilver intermediates derived from the nucleophilic addition of silver fluoride to gem-difluoroalkenes, this strategy bypasses the use of a strong base, thus enabling a mild and general synthetic method for ready access to non-symmetric α,α-disubstituted trifluoroethane derivatives.
- Tang, Hai-Jun,Lin, Ling-Zhi,Feng, Chao,Loh, Teck-Peng
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p. 9872 - 9876
(2017/08/08)
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- Visible light photocatalytic decarboxylative monofluoroalkenylation of α-amino acids with: Gem -difluoroalkenes
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α-Amino acids are among the most common biologically active molecules in nature, and their functionalization has attracted much attention. In this communication, a novel, efficient and general visible-light photocatalytic decarboxylative monofluoroalkenylation of N-protected α-amino acids with gem-difluoroalkenes is reported, affording the corresponding α-amino monofluoroalkenes which might find applications in medical chemistry and materials science. The reaction proceeded at room temperature with high efficiency and tolerance of various functional groups.
- Li, Jingjing,Lefebvre, Quentin,Yang, Haijun,Zhao, Yufen,Fu, Hua
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p. 10299 - 10302
(2017/09/25)
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- Discovery of Novel Pyridone-Conjugated Monosulfactams as Potent and Broad-Spectrum Antibiotics for Multidrug-Resistant Gram-Negative Infections
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Conjugating a siderophore to an antibiotic is a promising strategy to overcome the permeability-mediated resistance of Gram-negative pathogens. On the basis of the structure of BAL30072, novel pyridone-conjugated monosulfactams incorporating diverse substituents into the methylene linker between the 1,3-dihydroxypyridin-4(1H)-one and the aminothiazole oxime were designed and synthesized. Structure-activity relationship studies revealed that a variety of substituents were tolerated, with isopropyl (compound 12c) and methylthiomethyl (compound 16a) showing the best efficacy against multidrug-resistant (MDR) Gram-negative pathogens. In addition, compound 12c exhibits a good free fraction rate in an in vitro human plasma protein binding test, along with a low clearance and favorable plasma exposure in vivo. In a murine systemic infection model with MDR Klebsiella pneumoniae, compound 12c shows an ED50 of 10.20 mg/kg. Taken together, the results indicate that compound 12c is a promising drug candidate for the treatment of serious infections caused by MDR Gram-negative pathogens.
- Tan, Liang,Tao, Yunliang,Wang, Ting,Zou, Feng,Zhang, Shuhua,Kou, Qunhuan,Niu, Ao,Chen, Qian,Chu, Wenjing,Chen, Xiaoyan,Wang, Haidong,Yang, Yushe
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supporting information
p. 2669 - 2684
(2017/04/21)
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- Synthesis of Benzodihydrofurans by Asymmetric C?H Insertion Reactions of Donor/Donor Rhodium Carbenes
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Metal carbenes appended with two electron-donating groups, known as “donor/donor” carbenes, undergo diastereo- and enantioselective rhodium-catalyzed C?H insertion reactions with ether substrates to form benzodihydrofurans. Unlike the reactions of metal carbenes with electron-withdrawing groups attached, the attenuated electrophilicity enables these reactions to be conducted in Lewis basic solvents (e.g., acetonitrile) and in the presence of water. The diazo precursors for these species are prepared in situ from hydrazone using a mild and chemoselective oxidant (MnO2). Although this sequence often can be performed in one-pot, control experiments have elucidated why a “two-pot” process is often more efficient. A thorough screening of achiral catalysts demonstrated that sterically encumbered catalysts are optimal for diastereoselective reactions. Although efficient insertion into allylic and propargylic C?H bonds is observed, competing dipolar cycloaddition processes are noted for some substrates. The full substrate scope of this useful method of benzodihydrofuran synthesis, mechanisms of side reactions, and computational support for the origins of stereoselectivity are described.
- Lamb, Kellan N.,Squitieri, Richard A.,Chintala, Srinivasa R.,Kwong, Ada J.,Balmond, Edward I.,Soldi, Cristian,Dmitrenko, Olga,Casti?eira Reis, Marta,Chung, Ryan,Addison, J. Bennett,Fettinger, James C.,Hein, Jason E.,Tantillo, Dean J.,Fox, Joseph M.,Shaw, Jared T.
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supporting information
p. 11843 - 11855
(2017/09/07)
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- Direct and Stereospecific [3+2] Synthesis of Pyrrolidines from Simple Unactivated Alkenes
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Pyrrolidines are important heterocyclic compounds with endless applications in organic synthesis, metal catalysis, and organocatalysis. Their potential as ligands for first-row transition-metal catalysts inspired a new method to access complex poly-heterocyclic pyrrolidines in one step from available materials. This fundamental step forward is based on the discovery of an essential organoaluminum promoter that engages unactivated and electron-rich olefins in intermolecular [3+2] cycloadditions.
- Otero-Fraga, Jorge,Suárez-Pantiga, Samuel,Montesinos-Magraner, Marc,Rhein, Dennis,Mendoza, Abraham
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supporting information
p. 12962 - 12966
(2017/09/18)
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- Preparation method of mild diazomethane derivative
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The invention discloses a preparation method of a mild diazomethane derivative. The preparation method comprises that EWG-substituted benzene sulfonyl chloride and hydrazine hydrate undergo a reaction to produce EWG-substituted benzene sulfonyl chloride, the EWG-substituted benzene sulfonyl chloride and aldehyde or ketone undergo a reaction to produce EWG-substituted benzenesulfonylhydrazone, and the EWG-substituted benzenesulfonylhydrazone, a base and an organic solvent are mixed and undergo a replacement reaction to produce a diazomethane derivative. The diazomethane derivative is not separated and purified and is further used for a tension small ring synthesis reaction and an insertion reaction. The benzene ring of benzenesulfonylhydrazone is introduced with an electron-withdrawing group EWG, and through electron effects and steric hindrance effects, the benzenesulfonyl group on the benzenesulfonylhydrazone is easily separated so that a diazomethane derivative is produced under very mild conditions and especially at the room temperature.
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Paragraph 0134; 0139
(2017/08/28)
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- New applications of hetaryl thioketones for the synthesis of hetaryl-substituted ethenes via 'two-fold extrusion reaction'
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A series of aryl/hetaryl thioketones was applied for the reactions with aryl/hetaryldiazomethanes yielding, after elimination of N2, the corresponding thiiranes. The relatively unstable dihetaryldiazomethanes were generated in situ from the corresponding hydrazones by oxidation with DMSO. The obtained thiiranes were converted into tetraaryl/hetaryl-substituted ethenes in good yields by desulfurization performed with tris(diethylamino)phosphine ((Et2N)3P).
- Mlostoń, Grzegorz,Urbaniak, Katarzyna,Pawlak, Aneta,Heimgartner, Heinz
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p. 127 - 139
(2017/03/14)
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- Reaction of Diazo Compounds with Difluorocarbene: An Efficient Approach towards 1,1-Difluoroolefins
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A transition-metal-free difluoromethylenation of diazo compounds that proceeds under mild conditions has been developed and is based on the use of TMSCF2Br as the difluoromethylene source and tetrabutylammonium bromide (TBAB) as the promoter. T
- Zhang, Zhikun,Yu, Weizhi,Wu, Chenggui,Wang, Chengpeng,Zhang, Yan,Wang, Jianbo
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p. 273 - 277
(2016/01/25)
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- Development of a simple system for the oxidation of electron-rich diazo compounds to ketones
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Mild heating of diazo compounds in DMSO furnishes ketone products in moderate to excellent yields. The reaction is particularly effective on electron-rich substrates and exhibits high chemoselectivity, allowing for the use of diazo compounds containing additional oxidation-prone functional groups. This straightforward protocol offers an alternate route to synthetically useful α-ketoesters from readily available aryl diazoacetates.
- O'Connor, Nicholas R.,Bolgar, Peter,Stoltz, Brian M.
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supporting information
p. 849 - 851
(2016/02/05)
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- CARBIDOPA AND L-DOPA PRODRUGS AND THEIR USE TO TREAT PARKINSON'S DISEASE
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The present disclosure relates to (a) carbidopa prodrugs, (b) pharmaceutical combinations and compositions comprising a carbidopa prodrug and/or an L-dopa prodrug, and (c) methods of treating Parkinson's disease and associated conditions comprising administering a carbidopa prodrug and an L-dopa prodrug to a subject with Parkinson's disease.
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Paragraph 0317; 0320
(2016/05/24)
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- PROCESS FOR PRODUCING ISOXAZOLINE DERIVATIVES
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A process for producing isoxazoline derivatives by ring-opening and cyclization of the corresponding cyclopropane derivatives with electrophilic nitrosylation reagents.
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Paragraph 0019
(2016/05/09)
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- Fluorogenic Strain-Promoted Alkyne-Diazo Cycloadditions
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Fluorogenic reactions, in which non- or weakly fluorescent reagents produce highly fluorescent products, are attractive for detecting a broad range of compounds in the fields of bioconjugation and material sciences. Herein, we report that a dibenzocyclooctyne derivative modified with a cyclopropenone moiety (Fl-DIBO) can undergo fast strain-promoted cycloaddition reactions under catalyst-free conditions with azides, nitrones, nitrile oxides, as well as mono- and disubstituted diazo-derivatives. Although the reaction with nitrile oxides, nitrones, and disubstituted diazo compounds gave cycloadducts with low quantum yield, monosubstituted diazo reagents produced 1H-pyrazole derivatives that exhibited an approximately 160-fold fluorescence enhancement over Fl-DIBO combined with a greater than 10 000-fold increase in brightness. Concluding from quantum chemical calculations, fluorescence quenching of 3H-pyrazoles, which are formed by reaction with disubstituted diazo-derivatives, is likely due to the presence of energetically low-lying (n,π?) states. The fluorogenic probe Fl-DIBO was successfully employed for the labeling of diazo-tagged proteins without detectable background signal. Diazo-derivatives are emerging as attractive reporters for the labeling of biomolecules, and the studies presented herein demonstrate that Fl-DIBO can be employed for visualizing such biomolecules without the need for probe washout.
- Friscourt, Frédéric,Fahrni, Christoph J.,Boons, Geert-Jan
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p. 13996 - 14001
(2015/09/28)
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- gem-Difluoroolefination of Diazo Compounds with TMSCF3 or TMSCF2Br: Transition-Metal-Free Cross-Coupling of Two Carbene Precursors
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A new olefination protocol for transition-metal-free cross-coupling of two carbene fragments arising from two different sources, namely, a nonfluorinated carbene fragment resulting from a diazo compound and a difluorocarbene fragment derived from Ruppert-Prakash reagent (TMSCF3) or TMSCF2Br, has been developed. This gem-difluoroolefination proceeds through the direct nucleophilic addition of diazo compounds to difluorocarbene followed by elimination of N2. Compared to previously reported Cu-catalyzed gem-difluoroolefination of diazo compounds with TMSCF3, which possesses a narrow substrate scope due to a demanding requirement on the reactivity of diazo compounds and in-situ-generated CuCF3, this transition-metal-free protocol affords a general and efficient approach to various disubstituted 1,1-difluoroalkenes, including difluoroacrylates, diaryldifluoroolefins, as well as arylalkyldifluoroolefins. In view of the ready availability of diazo compounds and difluorocarbene reagents and versatile transformations of 1,1-difluoroalkenes, this new gem-difluoroolefination method is expected to find wide applications in organic synthesis.
- Hu, Mingyou,Ni, Chuanfa,Li, Lingchun,Han, Yongxin,Hu, Jinbo
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p. 14496 - 14501
(2015/11/27)
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- Cu(I)-catalyzed coupling of diaryldiazomethanes with terminal alkynes: An efficient synthesis of tri-aryl-substituted allenes
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A highly efficient method for the synthesis of tri-aryl-substituted allenes has been developed through Cu(I)-catalyzed coupling of diaryldiazomethanes with terminal alkynes. The reaction is under mild conditions and uses simple and inexpensive CuI as the catalyst. Mechanistically, the reaction follows a pathway involving Cu(I) carbene migratory insertion.
- Wu, Chenggui,Hu, Fangdong,Liu, Zhenxing,Deng, Guisheng,Ye, Fei,Zhang, Yan,Wang, Jianbo
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p. 9196 - 9201
(2015/11/27)
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- Cross-Coupling between Difluorocarbene and Carbene-Derived Intermediates Generated from Diazocompounds for the Synthesis of gem-Difluoroolefins
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Cross-coupling between difluorocarbene and carbene-derived intermediates generated from diazocompounds was developed to give gem-difluoroolefins, which constitutes a fast practical pathway to achieve hindered gem-difluoroolefins. The cross-coupling between difluorocarbene and aryl diazoacetates proceeded smoothly in the presence of a copper source, whereas its coupling with diaryl diazomethanes occurred well under metal-free conditions. A mechanism involving a copper-difluorocarbene complex was proposed.
- Zheng, Jian,Lin, Jin-Hong,Yu, Liu-Ying,Wei, Yun,Zheng, Xing,Xiao, Ji-Chang
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p. 6150 - 6153
(2016/01/09)
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- SMALL MOLECULE LFA-1 INHIBITORS
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The present invention relates to novel compounds which are capable of inhibiting the interaction of LFA-1 with its counter ligands.
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Page/Page column 115
(2016/01/01)
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- Evidence that Additions of Grignard Reagents to Aliphatic Aldehydes Do Not Involve Single-Electron-Transfer Processes
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Addition of allylmagnesium reagents to an aliphatic aldehyde bearing a radical clock gave only addition products and no evidence of ring-opened products that would suggest single-electron-transfer reactions. The analogous Barbier reaction also did not pro
- Otte, Douglas A. L.,Woerpel
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supporting information
p. 3906 - 3909
(2015/08/18)
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- 1-Phenyl-1,2,4,6-cycloheptatetraene: The missing intermediate of the diphenylcarbene to fluorene rearrangement
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The photochemistry of diphenylcarbene 5, matrix-isolated in argon at 3-5K was investigated by UV-Vis, IR, and EPR spectros-copy. Although carbene 5 proved to be stable toward broadband UV irradiation, it slowly rearranges to 1-phenyl-1,2,4,6-cycloheptatet
- Costa, Paolo,Sander, Wolfram
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- NOVEL CEPHALOSPORIN DERIVATIVE AND PHARMACEUTICAL COMPOSITION THEREOF
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The present invention relates to novel cephalosporin derivatives represented by Chemical Formula 1. Wherein, X, Y, L, R1, and R2 are as same as defined in the description of the invention. The present invention also relates to pharmaceutical antibiotic compositions comprising a novel celphalosporin derivative represented by Chemical Formula 1, a prodrug thereof, a hydrate thereof, a solvate thereof, an isomer thereof, or a pharmaceutically acceptable salt thereof as an effective ingredient. According to the present invention, novel cephalosporin derivatives, a prodrug thereof, a hydrate thereof, a solvate thereof, an isomer thereof, or a pharmaceutically acceptable salt thereof as an effective ingredient for the broad spectrum of antibiotic resistant, low toxicity, particularly in Gram-negative bacteria, which can be useful with strong antimicrobial activity.
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- Potassium N-iodo p-toluenesulfonamide (TsNIK, iodamine-T): A new reagent for the oxidation of hydrazones to diazo compounds
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A new reagent for the oxidation of hydrazones to diazo compounds is described. N-Iodo p-toluenesulfonamide (TsNIK, iodamine-T) allows the preparation of α-diazoesters, α-diazoamides, α-diazoketones and α-diazophosphonates in good yield and in high purity after a simple extractive work-up. α-Diazoesters were also obtained in high yield from the corresponding ketones through a one-pot process of hydrazone formation/oxidation. Diazo compounds: N-Iodo p-toluenesulfonamide (TsNIK, iodamine-T), readily prepared from p-toluenesulfonamide and iodine in aqueous KOH, is a new reagent for the oxidation of hydrazones to diazo compounds in good yields and high purity (see scheme).
- Nicolle, Simon M.,Moody, Christopher J.
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p. 4420 - 4425
(2014/05/06)
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- A Novel Synthesis of Arylsulfonyl Hydrazine Derivatives Via the Reaction of Arylsulfonyl Hydrazone Salts and Hydrazonoyl Chlorides
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An efficient method for the synthesis of arylsulfonyl hydrazines and diazo compounds via arylsulfonyl hydrazone salts is described. The reaction was performed in DMF using hydrazonoyl chlorides and sodium arylsulfonyl hydrazones, which were easily prepare
- Khalili, Gholamhossein
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p. 1882 - 1886
(2015/10/29)
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- The highly reactive benzhydryl cation isolated and stabilized in water ice
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Diphenylcarbene (DPC) shows a triplet ground-state lying approximately 3 kcal/mol below the lowest singlet state. Under the conditions of matrix isolation at 25 K, DPC reacts with single water molecules embedded in solid argon and switches its ground state from triplet to singlet by forming a strong hydrogen bond. The complex between DPC and water is only metastable, and even at 3 K the carbene center slowly inserts into the OH bond of water to form benzhydryl alcohol via quantum chemical tunneling. Surprisingly, if DPC is generated in amorphous water ice at 3 K, it is protonated instantaneously to give the benzhydryl cation. Under these conditions, the benzhydryl cation is stable, and warming to temperatures above 50 K is required to produce benzhydryl alcohol. Thus, for the first time, a highly electrophilic and extremely reactive secondary carbenium ion can be isolated in a neutral, nucleophilic environment avoiding superacidic conditions.
- Costa, Paolo,Fernandez-Oliva, Miguel,Sanchez-Garcia, Elsa,Sander, Wolfram
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supporting information
p. 15625 - 15630
(2015/01/16)
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- Copper-catalyzed gem -difluoroolefination of diazo compounds with TMSCF3 via C-F bond cleavage
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A novel Cu-catalyzed gem-difluoroolefination of diazo compounds is described. This transformation starts from readily available TMSCF3 and diazo compounds, via trifluoromethylation followed by C-F bond cleavage, to afford the desired 1,1-difluoroalkene products.
- Hu, Mingyou,He, Zhengbiao,Gao, Bing,Li, Lingchun,Ni, Chuanfa,Hu, Jinbo
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p. 17302 - 17305
(2014/01/06)
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- Pyrimidin-4-one derivatives and their use in the treatment, amelioration or prevention of a viral disease
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The present invention relates to a compound having the general formula II, optionally in the form of a pharmaceutically acceptable salt, solvate, polymorph, prodrug, tautomer, racemate, enantiomer, or diastereomer or mixture thereof, which is useful in treating, ameloriating or preventing a viral disease. Furthermore, specific combination therapies are disclosed.
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Paragraph 0417
(2013/05/08)
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- Heteroaryl hydroxamic acid derivatives and their use in the treatment, amelioration or prevention of a viral disease
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The present invention relates to a compound having the general formula I, optionally in the form of a pharmaceutically acceptable salt, solvate, polymorph, prodrug, tautomer, racemate, enantiomer, or diastereomer or mixture thereof, which is useful in treating, ameliorating or preventing a viral disease. Furthermore, specific combination therapies are disclosed.
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Paragraph 0402-0403
(2013/05/08)
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- Synthesis of tartaric acid analogues of FR258900 and their evaluation as glycogen phosphorylase inhibitors
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Di-O-cinnamoylated, -p-coumaroylated, and -feruloylated d-, l- and meso-tartaric acids were synthesized as analogues of the natural product FR258900, a glycogen phosphorylase (GP) inhibitor with in vivo antihyperglycaemic activity. The new compounds inhib
- Varga, Gergely,Docsa, Tibor,Gergely, Pál,Juhász, László,Somsák, László
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p. 1789 - 1792
(2013/04/10)
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