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Ene Reaction

Jie Chen, Hongfei Li, Hengchen Zhang, Xiaojuan Liao, Huijing Han, Lidong Zhang, Ruyi Sun, Meiran Xie
Ring-closure and ring-expansion techniques are the two routes for extensive synthesis of cyclic polymers. Here, we report an alternative blocking-cyclization technique referred to as the third route to prepare cyclic polymers with regulated ring size and ring number by ring-opening metathesis polymerization of di- and monofunctional monomers in a one-pot process, where the polymer intermediates bearing two single-stranded blocks are efficiently cyclized by the cyclizing unit of propagated ladderphane to generate corresponding mono-, bis-, and tricyclic polymers, and the well-defined ladderphane structure plays a crucial role in forming the cyclic topology...
December 14, 2018: Nature Communications
Sung-Eun Suh, Shuming Chen, K N Houk, David M Chenoweth
This article describes an experimental and computational investigation on the possible aryne reactivity modes in the course of the reaction of two highly energetic molecules, an aryne and a 1,2,4,5-tetrazine. Beyond the triple aryne-tetrazine (TAT) reaction, it was observed that combinations of several reactivity modes afford several heterocyclic compounds. Density Functional Theory (DFT) calculations of competition between a second Diels-Alder reaction and the nucleophilic addition pathways indicates the latter to be more favorable...
October 21, 2018: Chemical Science
Rasmus R Svejdal, Eleanor R Dickinson, Drago Sticker, Jörg P Kutter, Kasper D Rand
Hydrogen/deuterium exchange monitored by mass spectrometry (HDX-MS) has become a routine approach for sensitive analysis of the dynamic structure and interactions of proteins. However, transient conformational changes and weak affinity interactions found in many biological systems typically only perturb fast-exchanging amides in proteins. Detection of HDX changes for such amides require shorter deuterium labeling times (sub-second) than can be performed reproducibly by manual sample handling. Here, we describe the development and validation of a microfluidic chip capable of rapid on-chip protein labeling and reaction quenching...
December 10, 2018: Analytical Chemistry
Andrew N Chan, Walter J Wever, Elisabetta Massolo, Scott E Allen, Bo Li
The dithiolopyrrolone (DTP) natural products contain a unique ene-disulfide that is essential for their antimicrobial and anticancer activities. The ene-disulfide in some DTPs is oxidized to a cyclic thiosulfonate, but it is unknown how the DTP thiosulfonates react with biomolecules. We studied the reactivity of the thiosulfonate derivative of the DTP holomycin, oxo-holomycin, and discovered a unique redox reaction: oxo-holomycin is reduced to its parent disulfide, while oxidizing small molecule and protein thiols to disulfides...
December 7, 2018: Chemical Research in Toxicology
Jomana Al-Nu'airat, Bogdan Z Dlugogorski, Xiangpeng Gao, Nassim Zeinali, Jakub Skut, Phillip R Westmoreland, Ibukun Oluwoye, Mohammednoor Altarawneh
Photo-degradation of organic pollutants plays an important role in their removal from the environment. This study provides an experimental and theoretical account of the reaction of singlet oxygen O2(1Δg) with the biodegradable-resistant species of phenol in an aqueous medium. The experiments combine customised LED-photoreactors, high-performance liquid chromatography (HPLC), and electron paramagnetic resonance (EPR) imaging, employing rose bengal as a sensitiser. Guided by density functional theory (DFT) calculations at the M062X level, we report the mechanism of the reaction and its kinetic model...
December 5, 2018: Physical Chemistry Chemical Physics: PCCP
Luis Almagro, Manuel Nogueras, Margarita Suárez, Justo Cobo, Christopher Glidewell
Two new functionalized steroids containing both chloro and formyl substituents in ring A, and intended as precursors for the synthesis of hybrid systems, have been synthesized from ketosteroid precursors. 3-Chloro-2-formyl-17,17-dimethyl-18-nor-5α-androstane-2,13-diene, (I), and methyl 3-chloro-4-formyl-12-oxo-5β-cholan-3-ene-24-oate, C26 H37 ClO4 , (IV), have been synthesized using Vilsmeier reactions with 17β-hydroxy-17α-methyl-5α-androstan-3-one and methyl 3,13-dioxo-5β-cholan-24-oate, respectively...
December 1, 2018: Acta Crystallographica. Section C, Structural Chemistry
Pei Lay Yap, Shervin Kabiri, Diana N H Tran, Dusan Losic
Engineering of multifunctional binding chemistry on graphene composites using thiol-ene click reaction for selective and highly efficient adsorption of mercury (II) is demonstrated. Graphene oxide (GO) is used as an initial material for covalent attachment of cysteamine molecules by thiol-ene click reaction on C=C groups to achieve a partially reduced graphene surface with multiple binding chemistry such as O, S, and N. Batch adsorption studies showed remarkable adsorption rate with only 1 mg L-1 dosage of adsorbent used to remove 95 % Hg (II) (~1...
December 3, 2018: ACS Applied Materials & Interfaces
Mingchuang He, Zhaohua Yan, Fuyuan Zhu, Sen Lin
A copper-catalyzed iminyl radical-mediated C-C bond cleavage/cross-coupling tandem reaction of cyclobutanone oxime esters with aryl thiols in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) at room temperature was developed and aryl cyanopropyl sulfides were smoothly synthesized in 20-88% yields. By altering copper reagent and the molar ratio of cyclobutanone oxime ester/aryl thiol/DBU, substitutional products N-arylthio cyclobutanone imines were selectively generated in 50-91% yields. Using this protocol, C-S bond and N-S bond formations using aryl thiols as sulfur sources were realized under very mild conditions without the use of photocatalysis and electrocatalysis techniques...
November 30, 2018: Journal of Organic Chemistry
Peng An, Hsuan-Yi Wu, Tracey M Lewandowski, Qing Lin
Two hydrophilic spiroalkenes, azaspiro[2.3]hex-1-ene and azaspiro[2.4]hept-1-ene, were designed and synthesized. Compared to the previously reported spiro[2.3]hex-1-ene, the azaspiroalkenes exhibited greater water solubility and reactivity as dipolarophiles in the photoinduced tetrazole-alkene cycloaddition reaction. In addition, an azaspiro[2.3]hex-1-ene-containing amino acid, AsphK, was found to be charged by an engineered pyrrolysyl-tRNA synthetase into proteins via amber codon suppression in E. coli as well as in mammalian cells...
November 28, 2018: Chemical Communications: Chem Comm
Jiaoqin Liu, Chenguang Li, Ruijuan Qu, Jianfang Feng, Lianhong Wang
Tetrahydroperfluorocarboxylic acids (2H,2H,3H,3H-PFCAs) have aroused the interest of scholars worldwide due to their potential to generate perfluorinated compounds. In this work, we systematically examined the photodegradation kinetics and mechanisms of typical 2H,2H,3H,3H-PFCAs (Cn F2n+1 C2 H4 COOH, n = 6, 7, 8) in aqueous solution by a 500 W Hg lamp. The photodecomposition of 2H,2H,3H,3H-PFCAs all followed pseudo-first-order kinetics, and the photolysis rate coefficients increased with the increasing carbon chain length...
November 17, 2018: Science of the Total Environment
Hatice Mutlu, Ezgi Berfin Ceper, Xiaohui Li, Jingmei Yang, Wenyuan Dong, Mehmet Murat Ozmen, Patrick Theato
Sulfur and its functional groups are major players in an area of exciting research taking place in modern polymer and materials science, both in academia and industry. In fact, manifold sulfur-based reactions that are both exceptionally versatile as well as tremendously useful have been implemented, and further utilized for the design and preparation of polymeric materials that lead to a plethora of applications ranging from medicine to optics and nanotechnology to separation science. Hence, within this review, an overview of strategies and developments used over the last 5 years to reinforce the importance of the sulfur functional group in modern polymer and materials science is presented...
November 23, 2018: Macromolecular Rapid Communications
Shumei Xia, Yu Song, Xuedong Li, Hongru Li, Liang-Nian He
To circumvent the thermodynamic limitation of the synthesis of oxazolidinones starting from 2-aminoethanols and CO₂ and realize incorporation CO₂ under atmospheric pressure, a protic ionic liquid-facilitated three-component reaction of propargyl alcohols, CO₂ and 2-aminoethanols was developed to produce 2-oxazolidinones along with equal amount of α-hydroxyl ketones. The ionic liquid structure, reaction temperature and reaction time were in detail investigated. And 15 mol% 1,5,7-triazabicylo[4.4.0]dec-5-ene ([TBDH][TFE]) trifluoroethanol was found to be able to synergistically activate the substrate and CO₂, thus catalyzing this cascade reaction under atmospheric CO₂ pressure...
November 20, 2018: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Ngangbam Renubala Devi, Sabera Sultana, Madhurjya Borah, Anil K Saikia
Bismuth trifluoromethanesulfonate (Bi(OTf)3) can be efficiently used for the preparation of dihydropyrans from β-allenols and aldehydes by oxonium-ene reaction in good yields. The reaction is highly regioselective. On the other hand, the same reaction with trimethylsilyl trifluoromethanesulfonate (TMSOTf) at -45 oC affords hexahydropyrano[4,3-b]pyran skeleton in moderate yields.
November 21, 2018: Journal of Organic Chemistry
Liang Chen, Hao Min, Weilan Zeng, Xiaoming Zhu, Yun Liang, Guobo Deng, Yuan Yang
A novel, atom economical, and transition-metal-free strategy for the synthesis of thiophenes from substituted buta-1-enes with potassium sulfide has been presented. The reaction achieves double C-S bond formations via cleavage of multiple C-H bonds and provides an efficient approach to access various functionalized thiophenes. Moreover, the strategy can also be used for the synthesis of thiophenes from 1,4-diaryl-1,3-dienes. Mechanistically, DMSO plays a role of oxidant and S3 •- in situ generated from K2 S is involved...
November 21, 2018: Organic Letters
Patrick-Kurt Dannecker, Ansgar Sehlinger, Michael A R Meier
The synthesis of macrocycles based on the Ugi-4CR has been thoroughly explored by Wessjohann and coworkers, while polymerizations utilizing the Ugi-4CR are already patented by Ugi and recently studied more in detail, developing a new trend in polymer chemistry. Here, the combination of both, that is, the synthesis of polymacrocycles, is demonstrated. As diverse functional groups can be easily introduced in a macrocycle via Ugi-4CR, a straightforward design of polymacrocycles is achieved in a two-step procedure...
November 20, 2018: Macromolecular Rapid Communications
Haijun Lin, Baocheng Jiang, Chen Chen, Yan Song, Min Yang, Huilian Huang, Guangtong Chen
The microbial transformation of cycloastragenol (CA) by Mucor racemosus AS 3.20 was investigated. Seven isolated products were identified as (20R,24S)-3β,6α,16β,25- tetrahydroxy-20,24-epoxy-9,10-seco-cycloartan-9(11),10(19)-diene (1), (20R,24S)- 3β,6α,16β,25-tetrahydroxy-20,24-epoxy-9,10-seco-cycloartan-1(10),9(11)-diene (2), (20R,24S)-3β,16β,25-trihydroxy-6α,19α;20,24-diepoxy-9,10-seco-cycloartan-9(11)-ene (3), (20R,24S)-6α,16β,25-trihydroxy-3β,10β;20,24-diepoxy-9,10-seco- cycloartan-11-one (4), (20R,24S)-16β,25-dihydroxy-6α-methoxy-3β,10β;20,24- diepoxy-9,10-seco-cycloartan-7(8),9(11)-diene (5), (20R,24S)-6α,16β,25-trihydroxy-3β,10β;20,24-diepoxy-9,10-seco-cycloartan-9(11)-ene (6), and (20R,24S)-3β,6α,16β,25-tetrahydroxy-19-acetoxy-ranunculan-9(10)-ene (7) by spectroscopic analysis...
November 17, 2018: Natural Product Research
Gheorghe Duca, Aculina Aricu, Kaleria Kuchkova, Elena Secara, Alic Barba, Ion Dragalin, Nicon Ungur, Gabriella Spengler
Using sclareol and sclareolide as starting materials, the guanidine derivatives of 12-amino-11-dihomodrimane-8α-ol and 13-amino-14,15-bis-dinorlabd-8(9)-ene were synthesized by the reaction of the corresponding amines with sodium hydrogencyanamide in ethanol - water solution. Monoacyl- and diacylguanidines were prepared from activated with N,N-carbonyldiimidazole Δ8,9 -bicyclohomofarnesenoic acid by the reaction with guanidine. Their structures were confirmed by the 1 H and 13 C NMR, IR spectral and elemental analysis data...
November 16, 2018: Natural Product Research
Song Liu, Tao Zhang, Lei Zhu, Kangbao Zhong, Jianxian Gong, Zhen Yang, Ruopeng Bai, Yu Lan
Theoretical calculations have been performed to investigate the mechanism and stereoselectivity of rhodium-catalysed intramolecular [3+2] cycloaddition for construction of a substituted hexahydropentalene complex. A new C-C bond cleavage mechanism, retro-Aldol-type, is proposed and verified for this Rh-catalysed [3+2] cycloaddition reaction.
November 16, 2018: Chemical Communications: Chem Comm
Adriano Bof de Oliveira, Johannes Beck, Jörg Daniels
The reaction between 4,5,6,7-tetra-hydro-2-(4,5,6,7-tetra-hydro-1,3-benzodi-thiol-2-yl-idene)-1,3-benzodi-thiole (common name: 4,4',5,5',6,6',7,7'-octa-hydro-dibenzo-tetra-thia-fulvalene, OMTTF) and an excess of iodine in tetra-hydro-furan (THF) yielded the respective radical organic polyiodide salt, C14 H16 S4 + ·I3 - . The asymmetric unit contains one and a half formula unit of both the cation and the anion, with the half-ions completed through inversion symmetry. The (OMTTF + ) positive charge can be assigned by the bond distances and the planar structure of the C2 S2 C=CS2 C2 central fragment...
November 1, 2018: Acta Crystallographica. Section E, Crystallographic Communications
Shobanbabu Bommagani, Narsihma R Penthala, Sean Parkin, Peter A Crooks
The title compound, C21 H25 NO3 [systematic name: (1a R ,4 E ,7a S ,8 E ,10a S ,10b R )-8-(2-amino-benzyl-idene)-1a,5-dimethyl-2,3,6,7,7a,8,10a,10b-octa-hydro-oxireno[2',3':9,10]cyclo-deca-[1,2- b ]furan-9(1a H )-one], was synthesized by the reaction of parthenolide [systematic name (1a R ,7a S ,10a S ,10b S , E )-1a,5-dimethyl-8-methyl-ene-2,3,6,7,7a,8,10 a ,10b-octa-hydro-oxireno[2',3':9,10]cyclo-deca-[1,2- b ]furan-9(1a H )-one] with 2-iodo-aniline via Heck reaction conditions. The mol-ecule is composed of fused ten-, five- (lactone), and three-membered (epoxide) rings...
November 1, 2018: Acta Crystallographica. Section E, Crystallographic Communications
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