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Tetrahedron
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  • Graphical abstract TOC
    • Abstract: Publication date: 18 October 2018Source: Tetrahedron, Volume 74, Issue 42Author(s):
       
  • Graphical Abstract TOC contd
    • Abstract: Publication date: 18 October 2018Source: Tetrahedron, Volume 74, Issue 42Author(s):
       
  • Graphical abstract TOC
    • Abstract: Publication date: 18 October 2018Source: Tetrahedron, Volume 74, Issue 42Author(s):
       
  • Corrigendum to “Chemical-epigenetic method to enhance the chemodiversity
           of the marine algicolous fungus, Aspergillus terreus OUCMDZ-2739”
           [Tetrahedron 74 (2018) 83–87]
    • Abstract: Publication date: Available online 21 September 2018Source: TetrahedronAuthor(s): Kunlai Sun, Guoliang Zhu, Jiejie Hao, Yi Wang, Weiming Zhu
       
  • Corrigendum to “A catalytic Koenigs-Knorr glycosylation based on
           
    • Abstract: Publication date: Available online 21 September 2018Source: TetrahedronAuthor(s): Changwei Li, Haijing Liang, Zhan-xin Zhang, Zhaoyan Wang, Lan Yu, Huanxiang Liu, Fengli An, Shaohua Wang, Lixia Ma, Weihua Xue
       
  • Computational study of Rh(I)-Catalyzed Cycloaddition–Fragmentation of
           N-cyclopropylacrylamides
    • Abstract: Publication date: Available online 20 September 2018Source: TetrahedronAuthor(s): Shuting Lv, Yilu Xu, Juan LiRh-catalyzed cycloaddition–fragmentation of N-cyclopropylacrylamides is an effective method to directly obtain substituted azocanes. In this transformation, the challenging step is insertion of CO and alkene into the more hindered proximal cyclopropane C–C bond while avoiding competitive less hindered proximal C–C activation. Given the importance of this novel strategy, we performed a density functional theory study to clarify the catalytic mechanism. The calculations confirm that cleavage of the more hindered bond is more favorable than cleavage of the less hindered bond for Rh-catalyzed (7 + 1) cycloaddition of N-cyclopropylacrylamides. Comparison between Rh-catalyzed (3 + 1 + 2) and (7 + 1) cycloaddition shows that the coordination mode with different ligand plays a crucial role in enabling different C–C cleavage. The main factors responsible for the occurrence of β-hydride elimination rather than C–C reductive elimination are also discussed. The kinetic preference for β-hydride elimination can be attributed to the transition state of C–C reductive elimination being more distorted and forming in a much more concerted fashion than that of β-hydride elimination. Additionally, C4–H elimination is disfavored owing to weaker interaction energy compared with C7–H elimination by analyzing using the distortion/interaction model.Graphical abstractDFT calculations were performed to investigate the Rh-catalyzed N-directed C–C bond cleavage of three-membered cyclopropanes.Image 1
       
  • Mechanoenzymatic resolution of racemic chiral amines, a green technique
           for the synthesis of pharmaceutical building blocks
    • Abstract: Publication date: Available online 20 September 2018Source: TetrahedronAuthor(s): Mario Pérez-Venegas, Eusebio JuaristiVery recently, several successful biocatalytic processes using mechanical activation to carry out enantioselective reactions have been reported. The present work describes the use of Candida antarctica Lipase B (CALB) in the kinetic resolution of racemic chiral amines by means of High-Speed Ball Milling (HSBM), minimizing the use of solvent and reducing reaction times. This approach provides an efficient and easily scalable strategy that was used for the green synthesis of enantiopure Rasagiline, as an illustrative example.Graphical abstractImage 1
       
  • Nickel-catalyzed C(sp2)-H selenation of imidazo[1,2-α]pyridines with
           arylboronic acids or alkyl reagents using selenium powder
    • Abstract: Publication date: Available online 18 September 2018Source: TetrahedronAuthor(s): Jie Zhu, Wenhui Zhu, Ping Xie, Charles U. Pittman, Aihua ZhouA novel and efficient Ni-catalyzed aryl- and alkyl-selenation of imidazo[1,2-α]pyridines employing selenium powder has been developed for the first time. The significant advantages of this protocol are that it is an inexpensive nickel catalyst and exhibits broad functional-group compatibility and good reaction yields.Graphical abstractImage 1
       
  • Exploration of synthetic strategies for the stereoselective preparation of
           novel tetrahydrofuran-containing biaryls: A high-pressure promoted
           Diels-Alder approach
    • Abstract: Publication date: Available online 18 September 2018Source: TetrahedronAuthor(s): Francesca Piazzolla, Carlo Siciliano, Lucio Minuti, Andrea TemperiniThree stereoselective synthetic approaches to tetrahydrofuran-containing biaryl scaffolds are described. All approaches involve a high-pressure promoted Diels-Alder reaction of substituted diene with methyl propiolate to give, after aromatization, the corresponding biaryl. The tetrahydrofuran moiety can be created starting from aryl-Br or aryl-CO2Me functional groups through a γ-phenylseleno ketone intermediate.Graphical abstractImage 1
       
  • The rearrangement of 1H,1′H-spiro[quinoline-4,2′-quinoxaline]-2,3′
           (3H,4′H)-diones – A new and efficient method for the synthesis of
           4-(benzimidazol-2-yl)quinolin-2(1H)-ones
    • Abstract: Publication date: Available online 18 September 2018Source: TetrahedronAuthor(s): Vakhid A. Mamedov, Elena A. Khafizova, Victor V. Syakaev, Aidar T. Gubaidullin, Aida I. Samigullina, Nataliya E. Algaeva, Shamil K. LatypovA new and highly efficient method for the synthesis of 4-(benzimidazol-2-yl)quinolin-2(1H)-ones via the rearrangement of spiroquinoxalinones in moderate-to-excellent yields has been developed. The rearrangement represents a facile approach to medicinally important biheterocyclic compounds. Compared to other methods, the present protocol has a number of advantages such as – cost-effectiveness, avoidance of difficult of access quinolin-2-one and benzimidazole derivatives as reaction partners, and easy accessibility of starting materials, making it a highly practical approach to access various 4-(benzimidazol-2-yl)quinolin-2(1H)-ones.Graphical abstractImage 1
       
  • Palladium-catalyzed direct allylation of fluorinated benzothiadiazoles
           with allyl chlorides
    • Abstract: Publication date: Available online 18 September 2018Source: TetrahedronAuthor(s): Jing Wang, Yan-Bo Yu, Xingang ZhangA palladium catalyzed cross-coupling of fluorinated benzothiadiazoles (FBTs) with allyl chlorides is reported. The significant feature of this method is synthetic simplicity, providing a straightforward access to unsymmetrical and symmetrical alkylated FBT derivatives that are of interest in organic electronic and optoelectronic materials.Graphical abstractImage 1
       
  • Gas-liquid flow hydrogenation of nitroarenes: Efficient access to a
           pharmaceutically relevant pyrrolobenzo[1,4]diazepine scaffold
    • Abstract: Publication date: Available online 18 September 2018Source: TetrahedronAuthor(s): Eleni Dimitriou, Richard H. Jones, Robin G. Pritchard, Gavin J. Miller, Matthew O'BrienUsing a Tube-in-Tube device based on the amorphous Teflon AF-2400 fluoropolymer, a series of nitroarenes was hydrogenated to afford the corresponding aniline compounds. The system was then applied to the construction of a pyrrolobenzo[1,4]diazapene scaffold through a tandem hydrogenation-condensation-hydrogenation sequence.Graphical abstractImage 1
       
  • Catalytic hydroboration of aldehydes and ketones with sodium hydride:
           Application to chemoselective reduction of aldehydes over ketones
    • Abstract: Publication date: Available online 17 September 2018Source: TetrahedronAuthor(s): Won Kyu Shin, Hanbi Kim, Ashok Kumar Jaladi, Duk Keun AnSodium hydride-promoted catalytic hydroboration of aldehydes and ketones with pinacolborane (HBpin) was examined, and 10 mol% of NaH was found to cause the HBpin to participate in hydroboration in a convenient and efficient manner at mild reaction conditions. Further chemoselective hydroboration of aldehyde over ketone functionality was also analyzed. In addition, no hydroboration was observed form ester, acyl chloride, amide, nitrile, alkene, alkyne, alkyl halide and epoxide functional groups indicate that present system (HBpin, NaH) is highly selective for aldehydes and ketones.Graphical abstractImage 1
       
  • Improvement of chemical stability of conjugated dienes by chlorine
           substitution
    • Abstract: Publication date: Available online 17 September 2018Source: TetrahedronAuthor(s): Tetsuo Narumi, Takuma Nishizawa, Tomoyuki Imai, Ryuji Kyan, Hiroki Taniguchi, Kohei Sato, Nobuyuki MaseConjugated systems have versatile utilities in various fields including organic synthesis, pharmaceutical development, and material science. Such systems take advantage of their properties, which include their unique reactivity, relatively rigid structures, and low HOMO-LUMO gap energies. Their utility and the handling of conjugated systems however are both limited by excessively high photosensitivity and reactivity. We now report a novel molecular approach to the improvement of the chemical stability of the acyclic conjugated system against the photolysis and oxidation reactions simply by introduction of a chlorine atom into the conjugated system. Systematic studies of substrates with various substituents reveals that the improved chemical stability is based on the additive effects of the steric and electronic properties of the chlorine atom substituent.Graphical abstractImage 1
       
  • Cascade reactions as efficient and universal tools for construction and
           modification of 6-, 5-, 4- and 3-membered sulfur heterocycles of
           biological relevance
    • Abstract: Publication date: Available online 15 September 2018Source: TetrahedronAuthor(s): Piotr Przybylski, Katarzyna Pyta-Klich, Krystian Pyta, Anna JanasSulfur-heterocycles are found in nature and they are recognized by biological systems as effective pharmacophores inducing anticancer, antimicrobial, antiviral, anti-diabetic activities via e.g. blocking functionality of many enzymes and receptors. Due to the biological importance of sulfur heterocycles, novel and efficient synthetic strategies, opening the access to regio- and stereoselective construction and functionalization of these scaffolds are in high demand. The advantages and some limitations of tandem strategies are discussed in view of challenges related to the construction of adequately functionalized or fused main heterocyclic sulfur frameworks of biological interest. In addition, examples of sulfur-heterocycles of important biological potency as well as domino reaction mechanisms revealing novel possibilities and ideas for construction of these attractive molecules, are reviewed. Bibliography presented in this review contains references to papers, which appeared mainly during the period from 2009 to 2018.Graphical abstractImage 1
       
  • Copper-catalyzed radical oxytrifluoromethylation of alkenyl oximes at
           ambient temperature
    • Abstract: Publication date: 11 October 2018Source: Tetrahedron, Volume 74, Issue 41Author(s): Xi-Tao Li, Ling Lv, Qiang-Shuai Gu, Xin-Yuan LiuA mild and efficient copper-catalyzed radical oxytrifluoromethylation reaction of alkenyl oximes was successfully developed. The method provides a straightforward access to a wide range of CF3-containing isoxazolines in good to excellent yields.Graphical abstractImage 1
       
  • Graphical abstract TOC
    • Abstract: Publication date: 11 October 2018Source: Tetrahedron, Volume 74, Issue 41Author(s):
       
  • Bifunctional thiophosphinamide catalyzed highly enantioselective Michael
           addition of acetone to (E)-2-azido β-nitrostyrenes and the subsequent
           reductive cyclization
    • Abstract: Publication date: 11 October 2018Source: Tetrahedron, Volume 74, Issue 41Author(s): Hao Zhang, Youming Wang, Zhenghong ZhouWe have proven that primary amine/thiophosphinamide incorporating (1R,2R)-1,2-diphenylethane-1,2-diamine is an efficient catalyst for the asymmetric Michael addition of acetone to (E)-2-azido β-nitrostyrenes. Under the optimal reaction conditions, the corresponding Michael addition products were obtained in excellent yields with almost perfect stereocontrol. Upon treatment with Et3SiH/InCl3, the Michael addition products could be successfully converted to the related 2-methyltetrahydroquinolines in acceptable yields with moderate to excellent diastereoselectivity and without appreciable loss in optical purity. This process provides a highly enantioselective pathway for the synthesis of biologically important 2-methyltetrahydroquinoline derivatives.Graphical abstractImage 1
       
  • Highly efficient synthesis of 1,2-disubstituted acetylenes derivatives
           from the cross-coupling reactions of 1-bromoalkynes with organoalane
           reagents
    • Abstract: Publication date: 11 October 2018Source: Tetrahedron, Volume 74, Issue 41Author(s): Xue-Bei Shao, Xin Jiang, Qing-Han Li, Zhi-Gang ZhaoA Highly efficient route for the synthesis of 1,2-disubstituted acetylene derivatives has been developed by palladium catalyzed cross-couplings of alkynyl halides with (hetero)aryl aluminium reagents under mild conditions. This has given corresponding cross-coupling products good to excellent isolated yields of up to 99%. The aryls bearing electron-donating or electron-withdrawing groups in either alkynylhalides or arylaluminum substrates gave cross-coupling products good yields. This process was simple and easily performed, which provides an efficient method for the synthesis of 1,2-disubstituted acetylenes derivatives. On the basis of the experimental results, a possible catalytic cycle has been proposed.Graphical abstractImage 1
       
  • Efficient 2-aryl benzothiazole formation from acetophenones, anilines, and
           elemental sulfur by iodine-catalyzed oxidative C(CO)-C(alkyl) bond
           cleavage
    • Abstract: Publication date: 11 October 2018Source: Tetrahedron, Volume 74, Issue 41Author(s): Yafeng Liu, Xinglong Yuan, Xin Guo, Xueguo Zhang, Baohua ChenA novel and efficient iodine-catalyzed one-pot reaction of aromatic amines, acetophenones, and elemental sulfur for the synthesis of 2-aryl benzothiazoles is described. The process involves sequential C−S and C-N bond formation followed by C(CO)−C bond cleavage from readily accessible starting materials. A wide range of functional groups is tolerated under oxidant and metal-free condition and moderate to good product yields are obtained.Graphical abstractImage 1
       
  • Studies towards iodine-catalyzed dehydrative-cycloisomerization of
           pent-4-yne-1,2-diols to di- and tri-substituted furans
    • Abstract: Publication date: 11 October 2018Source: Tetrahedron, Volume 74, Issue 41Author(s): H. Surya Prakash Rao, Vijjapu Satish, Silambarasan Kanniyappan, Priyanka KumariAn efficient and single-step iodine catalyzed and metal-free synthesis of di and tri-substituted 2-methylfuran derivatives were achieved from 1-popargyl-1,2-diols. Stereospecific synthesis of starting 1,2-diols was achieved by indium mediated Barbier type propargylation on corresponding keto-alcohols or by sodium borohydride mediated reduction of 2-hydroxy-2-propargyl ketones. The furan synthesis proceeded through iodine mediated 5-exo-trig cyclization, dehydration and reductive deiodination. The method was applied to the synthesis of 2-methylfuran fused to phenanthrene, pyrene and acenaphthylene rings.Graphical abstractImage 1
       
  • Graphical Abstract TOC cont'd
    • Abstract: Publication date: 11 October 2018Source: Tetrahedron, Volume 74, Issue 41Author(s):
       
  • Palladium-catalyzed synthesis of 3-trifluoromethylated 1,3-dienes from
           acrylate derivatives and BTP
    • Abstract: Publication date: 11 October 2018Source: Tetrahedron, Volume 74, Issue 41Author(s): Qun Zhao, Jianjun Wang, Tatiana Besset, Xavier Pannecoucke, Jean-Philippe Bouillon, Thomas PoissonHere we reported a Pd-catalyzed coupling reaction between acrylate derivatives and BTP (2-bromo-3,3,3-trifluoropropene) to access 3-trifluoromethylated 1,3-dienes. The reaction allows the formation of the corresponding products in good to excellent yields and moderate Z/E diastereoisomeric ratios. This method broadens the current toolbox to access 3-trifluoromethylated 1,3-dienes.Graphical abstractImage 1
       
  • Enantioselective palladium-catalyzed addition of malonates to
           3,3-difluoropropenes
    • Abstract: Publication date: 11 October 2018Source: Tetrahedron, Volume 74, Issue 41Author(s): Myriam Drouin, Jean-François PaquinMonofluoroalkenes bearing a malonate unit at the β position can be synthesized by the enantioselective addition of diesters to 3,3-difluoropropenes. The difference in reactivity regarding the geometry and the substituents of the alkene of the 3,3-difluoropropenes, as well as the alkyl groups of the malonates, was studied and limitations were identified. The reaction was also performed with different 3,3-difluoropropenes. Further synthetic transformations of a newly functionalized monofluoroalkene were also accomplished.Graphical abstractImage 1
       
  • Rapid and scalable synthesis of chiral bromolactones as precursors to
           α-exo-methylene-γ-butyrolactone-containing sesquiterpene lactones
    • Abstract: Publication date: 11 October 2018Source: Tetrahedron, Volume 74, Issue 41Author(s): Roman Lagoutte, Miryam Pastor, Mathéo Berthet, Nicolas WinssingerThe sesquiterpene lactones cover a diverse and pharmacologically important diversity space. In particular, the electrophilic α-exo-methylene-γ-butyrolactone moiety that is preponderant in this natural product family has been shown to readily engage in covalent inhibition via conjugate addition of cysteine residues in target proteins. However, the synthetic accessibility of sesquiterpenes or related probes to investigate their mode of action remains laborious. Herein, we present a rapid and scalable route to chiral bromolactones as enabling precursors in the synthesis of sesquiterpene lactones.Graphical abstractImage 1
       
  • Synthesis of modular building blocks using glycosyl phosphate donors for
           the construction of asymmetric N-glycans
    • Abstract: Publication date: 11 October 2018Source: Tetrahedron, Volume 74, Issue 41Author(s): Supriya Dey, Sumit O. Bajaj, Tsung-I. Tsai, Hong-Jay Lo, Kevin Wu, Chi-Huey WongGlycosyl phosphates are known as versatile donors for the synthesis of complex oligosaccharides both chemically and enzymatically. Herein, we report the stereoselective construction of modular building blocks for the synthesis of N-glycan using glycosyl phosphates as donors. We have synthesized four trisaccharide building blocks with orthogonal protecting groups, namely, Manβ2GlcNAc(OAc)3β6GlcNAc (9), Manβ2GlcNAc-β6GlcNAc(OAc)3 (15), Manβ2GlcNAc(OAc)3β4GlcNAc (18) and Manβ2GlcNAcβ4GlcNAc(OAc) (22) for further selective elongation using glycosyltransferases. The glycosylation reaction using glycosyl phosphate was found to be high yielding with shorter reaction time. Initially, The phthalimide protected glucosamine donor was exploited to ensure the formation of β-glycosidic linkage and later converted to the N-acetyl group before the enzymatic synthesis. The selective deprotection of O-benzyl group was performed prior to enzymatic synthesis to avoid its negative interference.Graphical abstractImage 1
       
  • Graphical abstract TOC
    • Abstract: Publication date: 11 October 2018Source: Tetrahedron, Volume 74, Issue 41Author(s):
       
  • Iminium ion-enamine cascade reaction enables the asymmetric total
           syntheses of aspidosperma alkaloids vincadifformine and ervinceine
    • Abstract: Publication date: Available online 15 September 2018Source: TetrahedronAuthor(s): Ganesh Pandey, Jagadish Khamrai, Akash Mishra, Pulak Maity, Prasanna Kumara ChikkadeAsymmetric total synthesis of (+)-vincadifformine and (+)-ervinceine is reported by utilizing an iminium ion triggered cascade reaction using chiral 3,3-disubstituted piperidine imine and 2,3-disubstituted indole derivatives coupling partner. In the first generation total synthesis, the pivotal imine is prepared in excellent stereoselectivity but in moderate yield involving a Birch reduction-alkylation strategy. Furthermore, to improve upon the synthesis of the decisive imine, the more practical second generation route is devised through a Johnson-Claisen rearrangement to access chiral 3,3-disubstituted piperidinone in excellent yield and stereoselectivity. Apart from synthesizing (+)-vincadifformine, this strategy is also exploited for the first asymmetric total synthesis of (+)-ervinceine employing an iminium ion mediated cascade reaction. This distinctive strategy simultaneously sets up two new rings, two new stereogenic centers, and three new sigma bonds in a single operation.Graphical abstractImage 1
       
  • Highly sensitive and selective “naked eye” sensing of Cu(II) by a
           novel acridine-based sensor both in aqueous solution and on the test kit
    • Abstract: Publication date: Available online 15 September 2018Source: TetrahedronAuthor(s): Qiuzi Dai, Chunmei Gao, Yijia Liu, Haiyang Liu, Boren Xiao, Chengken Chen, Jiwei Chen, Zigao Yuan, Yuyang JiangA highly selective and sensitive acridine-based colorimetric sensor 2-((7-chloro-2-methoxybenzo[b][1,5]naphthyridin-10-yl)amino)phenol (NAP) was developed for detection of Cu2+ ions both in aqueous solution and on test papers. Sensor NAP responses to Cu2+ ions by changing its color from yellow to pink, which could be easily observed by the naked eyes. Furthermore, the mechanism of the binding model of NAP-Cu2+ complex was investigated by 1H NMR, HRMS analysis, and DFT calculations.Graphical abstractThe first acridine derivative used as a colorimetric sensor for Cu2+ detection was reported with a color change from yellow to pink observed by naked-eyes.Image 1
       
  • Enantioselective synthesis of indolo[2,3-b]-dihydrothiopyranones via [3+3]
           cycloaddition of chiral α,β-unsaturated acylammonium salts
    • Abstract: Publication date: Available online 14 September 2018Source: TetrahedronAuthor(s): Jing-Hai Jin, Xiang-Yu Li, Xiaoyan Luo, Wei-Ping DengA nucleophile-catalyzed Michael addition/proton transfer/lactonization (NCMPL) organocascade process of chiral α,β-unsaturated acylammonium salts and indoline-2-thiones is described, which delivers the indolo[2,3-b]dihydrothiopyranone motifs in high yields (up to 97%) with good to excellent enantioselectivities (up to 98% ee).Graphical abstractImage 1
       
  • Ozone, chemical reactivity and biological functions
    • Abstract: Publication date: Available online 14 September 2018Source: TetrahedronAuthor(s): Gérard Audran, Sylvain R.A. Marque, Maurice SantelliVarious aspects of the structure, the reactivity in organic synthesis, in the atmosphere, in environment, in biology of ozone are described. Emphasis is placed on the relation with singlet oxygen and dihydrotrioxide.Graphical abstractOzone structure; Reactions with alkenes; Ozonation of heteroatoms and carbon radicals; Ozonolyse in gas phase; in the atmosphere; Ozonation of C–H bonds; Hydrogen trioxide; Peroxone; Ozone in biology; Natural ozonides.Image 1
       
  • Synthesis of fluorinated amino acid derivatives through late-stage
           deoxyfluorinations
    • Abstract: Publication date: Available online 14 September 2018Source: TetrahedronAuthor(s): Attila Márió Remete, Melinda Nonn, Santos Fustero, Ferenc Fülöp, Loránd KissFluorine chemistry has represented a hot topic in drug research over the last decade. Because of their pharmaceutical potential, fluorine-containing amino acids and related derivatives have acquired high importance among medicinal chemists. Therefore their synthesis and the development of various synthetic methods for these types of molecular scaffolds have gained increasing interest in synthetic organic chemistry. The current review focuses on synthetic protocols towards fluorine-containing amino acid derivatives through late-stage fluorination with various nucleophilic reagents, describing the access of various open-chain and cyclic α-, β-, γ-amino acid derivatives.Graphical abstractImage 1
       
  • Application of copper(II)-mediated radical cross-dehydrogenative coupling
           to prepare spirocyclic oxindoles and to a formal total synthesis of
           Satavaptan
    • Abstract: Publication date: Available online 13 September 2018Source: TetrahedronAuthor(s): Timothy E. Hurst, Ryan Gorman, Pauline Drouhin, Richard J.K. TaylorApplication of radical cross-dehydrogenative coupling (CDC) procedures to prepare a range of novel spirocyclic oxindoles and to a formal total synthesis of the vasopressin V2 receptor antagonist Satavaptan is reported. The key step involves a copper-mediated oxidative cyclisation of a simple linear anilide precursor to give the spirocyclic oxindole core. This synthetic approach was also used to prepare novel Satavaptan scaffolds and analogues.Graphical abstractImage 1
       
  • Catalytic trifluoromethoxylation reactions
    • Abstract: Publication date: Available online 13 September 2018Source: TetrahedronAuthor(s): Katarzyna N. Lee, Johnny W. Lee, Ming-Yu NgaiTrifluoromethoxy (OCF3) group exhibits unique properties, which render it a highly desirable structural motif in life and materials sciences. The numbers of newly synthesized trifluoromethyl ethers are booming as new synthetic methods are constantly being developed to access these valuable compounds. This Review summarizes recent catalytic approaches towards preparation of trifluoromethyl ethers. Alkene, allylic, benzylic, and aryl trifluoromethoxylation reactions are discussed herein.Graphical abstractImage 1
       
  • Functionalized N-containing heterocyclic scaffolds derived from
           N-substituted pyrroles via inter- and intramolecular annulations
    • Abstract: Publication date: Available online 12 September 2018Source: TetrahedronAuthor(s): Nana Shao, Jinbiao Li, Huajian Zhu, Shuaizhong Zhang, Hongbin ZouTwo series of N-containing heterocycles were synthesized by one-step intramolecular or intermolecular annulations of N-substituted pyrrole-2-carbaldehydes and pyrrole-2-carbonitriles. These facile and atom-economic synthetic routes involved the inherent three potential electrophilic and nucleophilic reactive sites of the synthons and the reaction solvent plays a crucial role leading to these different types of products. Additionally, plausible mechanisms are proposed.Graphical abstractImage 1
       
  • A dehydrative arylation and thiolation of tertiary alcohols catalyzed by
           in situ generated triflic acid - Viable protocol for C-C and C-S bond
           formation
    • Abstract: Publication date: Available online 12 September 2018Source: TetrahedronAuthor(s): Deblina Roy, Gautam PandaThe title paper discusses a mild strategy for an efficient CC and CS bond formation through ortho-quinone methide intermediate. A total of 29 examples (23 tetrasubstituted methanes with a quaternary carbon center and 6 triarylmethyl thioarenes) with diverse substitution patterns could be prepared in high yields (up to 82%). Use of indium triflate allowed the transformation to be carried out in an open flask without taking special care leaving water as the only by product. Control experiments revealed that the triflic acid generated in situ from indium triflate, probably through the coordination with substrate, acted as the actual catalyst for the transformation. Further this protocol can be utilized for the synthesis of promising bioactives such as CDRI-830 analogues, dihydrochromeno[2,3-b]indoles and 9-(1H-indol-3-yl)-9-phenyl-9H-xanthen-1-ol.Graphical abstractImage 1
       
  • Ruthenium-catalyzed annulation of aromatic ketones with internal alkynes:
           A reliable route to substituted naphthalene derivatives
    • Abstract: Publication date: Available online 12 September 2018Source: TetrahedronAuthor(s): Jie Gao, Shujia Zhang, Yuhong ZhangWe report herein the preparation of polysubstituted naphthalene derivatives by the ruthenium-catalyzed benzannulation reaction of aromatic ketones with internal alkynes. This method (1) forms two new carbon-carbon bonds in one single step, (2) accommodates a variety of functional groups, and (3) undergoes mild reaction conditions.Graphical abstractImage 1
       
  • Formyloxyacetoxyphenylmethane and 1,1-diacylals as versatile O-formylating
           and O-acylating reagents for alcohols
    • Abstract: Publication date: Available online 11 September 2018Source: TetrahedronAuthor(s): Robert S.L. Chapman, Molly Francis, Ruth Lawrence, Joshua D. Tibbetts, Steven D. BullFormyloxyacetoxyphenylmethane, symmetric 1,1-diacylals and mixed 1-pivaloxy-1-acyloxy-1-phenylmethanes have been used as moisture stable O-formylating and O-acylating reagents for primary and secondary alcohols, allylic alcohols and phenols under solvent/catalyst free conditions to afford their corresponding esters in good yield.Graphical abstractImage 1
       
  • Oxidative radical phosphonotrifluoromethylthiolation of unactivated
           alkenes with alkyl phosphonate, silver(I) trifluoromethanethiolate and
           potassium persulfate
    • Abstract: Publication date: Available online 11 September 2018Source: TetrahedronAuthor(s): Zhiwei Xiao, Yongan Liu, Liping Zheng, Xiumiao Zhou, Youzhuan Xie, Chao Liu, Yong Guo, Qing-Yun ChenWe report herein a mild and efficient oxidative radical intermolecular phosphonotrifluoromethylthiolation of unactivated alkenes with good functional group tolerance. The reaction operates via a radical pathway involving oxidative generation of phosphonyl radicals and umpolung radical coupling of silver trifluoromethanethiolate.Graphical abstractImage 1
       
  • Investigation for the cyclization efficiency of linear tetrapeptides:
           Synthesis of tentoxin B and dihydrotentoxin
    • Abstract: Publication date: Available online 8 September 2018Source: TetrahedronAuthor(s): Ryota Sato, Kie Oyama, Hiroyuki KonnoInvestigation of the cyclization efficiency of N-methyl linear tetrapeptides using a molecular modeling study and chemical synthesis is described. The linear peptide with two N-methyl groups, MeAla-Leu-MePhe-Gly, forms γ-turn like conformation with the amine at N-terminus and the carbonyl at C-terminus in closer proximity to give the desired cyclic tetrapeptide, dihydrotentoxin. In addition, synthesis of tentoxin B by the combination of Fmoc solid-phase peptide synthesis and cyclization in solution phase has been reported. An unusual amino acid, an L-N-methyl-β-hydroxyphenylalanine derivative, which was assembled on solid support, was prepared from ethyl cinnamate. Cyclic tetrapeptide formation and cleavage of benzyl ether were optimized with DIPCI/HOBt/DIPEA and Et3SiH/Pd(OH)2, respectively.Graphical abstractImage 1
       
  • A multi-controllable selective fluorescent turn-on chemosensor for Al3+
           and Zn2+ based on a new diarylethene with a
           3-(4-methylphenyl)-1H-pyrazol-5-amine Schiff base group
    • Abstract: Publication date: Available online 8 September 2018Source: TetrahedronAuthor(s): Wendan Gao, Yaping Zhang, Hui Li, Shouzhi PuA novel diarylethene containing a 3-(4-methylphenyl)-1H-pyrazol-5-amine was synthesized. Its multi-responsive properties induced by UV/Vis lights and metal ions were studied in detail by absorption and fluorescence emission spectroscopy. It showed excellent fluorescence sensing ability for Al3+ and Zn2+ with very low detection limit. In addition, based on the multi-responsive characteristics, a logic circuit was constructed by using both UV/Vis lights and chemical species stimuli as inputs and fluorescence intensity as outputs. Moreover, the diarylethene was successfully applied to effectively detect Al3+ and Zn2+ in actual water samples.Graphical abstractImage 1
       
  • Mechanistic studies of hydrogen-peroxide-mediated anthocyanin oxidation
    • Abstract: Publication date: Available online 8 September 2018Source: TetrahedronAuthor(s): Ryuya Satake, Emiko YanaseThe oxidation of cyanidin-3-O-glucoside by hydrogen peroxide was investigated in a range of solvents. The reaction products had chemical structures identical to those formed by the reaction of this compound with the alkylperoxyl radical 2,2ʹ-azobis(2,4-dimethyl)valeronitrile. A plausible oxidation mechanism was proposed based on the obtained reaction products, and this mechanism was confirmed by HPLC–MS experiments using 18O-labeled reagents. Further, the reaction conditions were found to influence both the reaction rate and the products formed during the transformation, which validated the proposed mechanism.Graphical abstractImage 1
       
  • Synthesis of N-aminopyrazoles by Fe(II)-catalyzed rearrangement of
           4-hydrazonomethyl-substituted isoxazoles
    • Abstract: Publication date: Available online 6 September 2018Source: TetrahedronAuthor(s): Ekaterina E. Galenko, Viktor K. Ivanov, Mikhail S. Novikov, Andrey A. Zolotarev, Alexander F. KhlebnikovA novel effective method is reported for the preparation of 1-amino-1H-pyrazole-4-carboxylic acid derivatives by Fe(II)-catalyzed rearrangement of isoxazoles having (2,4-dinitrophenylhydrazono)methyl substituent at C4. The reaction proceeds smoothly for both E and Z isomers of 4-(hydrazonomethyl)isoxazoles, and this means it is not necessary to separate mixtures of E/Z-isomers of the hydrazones prepared by reaction of 5-methoxy/pirrolidino-4-carbonylisoxazoles and 2,4-dinitrophenylhydrazine. The rearrangement proceeds via the formation of an aziridine intermediate which can be isolated in certain cases. The 2-nitro group in the synthesized 1-[(2,4-dinitrophenyl)amino]-1H-pyrazole-4-carboxylic esters can be selectively reduced in two steps via acylation of the amino group followed by hydrogenation-deacylation using H2-Pd/C.Graphical abstractImage 1
       
  • Palladium catalysed regio- and stereoselective synthesis of
           (E)-4-aryl-1,3-bis(trimethylsilyl)but-3-en-1-ynes
    • Abstract: Publication date: Available online 6 September 2018Source: TetrahedronAuthor(s): Szymon Rogalski, Maciej Kubicki, Cezary PietraszukA practical and general synthetic approach to a series of 4-aryl-but-3-en-1-ynes is described. In the presence of palladium complexes a variety of aryl bromides (or iodides) undergo coupling with two equivalents of trimethylsilylacetylene with the formation of (E)-4-aryl-1,3-bis(trimethylsilyl)but-3-en-1-ynes. The protocol is simple, efficient, and affords synthesis of regio- and stereoselectively target products in good to high yields.Graphical abstractImage 1
       
  • Diversity-oriented synthesis of
           1,2,3,5-tetrahydrobenzo[e][1,2,4]oxadiazepines and
           2,3-dihydro-1H-benzo[e][1,2,4]triazepines by base-induced [4 + 3]
           annulation reactions
    • Abstract: Publication date: Available online 6 September 2018Source: TetrahedronAuthor(s): Wuyan Long, Shuangqun Chen, Xiaohong Zhang, Ling Fang, Zhiyong WangThe base-induced formal [4 + 3] annulation reactions of N-(ortho-chloromethyl)aryl amides with nitrones or hydrazonoyl chlorides have been reported. When nitrones are used as the 1,3-dipole, the corresponding reaction afforded a series of 1,2,3,5-tetrahydrobenzo[e][1,2,4]oxadiazepine derivatives. Highly functionalized 2,3-dihydro-1H-benzo[e][1,2,4]triazepine derivatives were also synthesized via an unprecedented tandem aza-Michael addition/rearrangement aromatization between N-(ortho-chloromethyl)aryl amides and hydrazonoyl chlorides.Graphical abstractImage 1
       
  • Efficient and facile strategy to substituted 2-aminothiazoles via ring
           opening of α-nitroepoxides
    • Abstract: Publication date: Available online 6 September 2018Source: TetrahedronAuthor(s): Yue Zhu, Qilin Wang, Haofan Luo, Guolin Zhang, Yongping YuA novel and efficient reaction has been developed to synthesize a set of substituted 2-aminothiazoles from α-nitroepoxides and ammonium thiocyanate. This reaction could proceed smoothly at mild condition, to afford products for a wide range of substrates with good to excellent yields. A possible mechanism has also been proposed.Graphical abstractImage 1
       
  • Organocatalytic asymmetric fulvene formation
    • Abstract: Publication date: Available online 6 September 2018Source: TetrahedronAuthor(s): Paul Sieverding, Johanna Osterbrink, Paul KögerlerThe first catalytic asymmetric formation of a fulvene from a racemic α,α-disubstituted aldehyde has been developed. Dynamic kinetic resolution of rac-2-phenylpropanal by a simple, modularly designed supramolecular organocatalyst consisting of inexpensive components has been established, producing the desired fulvene in good yields and moderate enantioselectivities. Herein we propose a mechanistic interpretation of the observed solvent- and additive-induced stereoselectivity reversal.Graphical abstractImage 1
       
  • An efficient deprotection method for
           5′-[O,O-bis(pivaloyloxymethyl)]-(E)-vinylphosphonate containing
           oligonucleotides
    • Abstract: Publication date: Available online 5 September 2018Source: TetrahedronAuthor(s): Jonathan O'Shea, Christopher S. Theile, Rajat Das, I. Ramesh Babu, Klaus Charisse, Muthiah Manoharan, Martin A. Maier, Ivan Zlatev5′-(E)-Vinylphosphonate (VP) is an effective bioisostere of the natural 5′-monophosphate in small interfering RNAs (siRNAs). Solid-phase synthesis of VP-siRNAs requires the use of appropriately protected VP-phosphoramidites in combination with optimal oligonucleotide deprotection conditions. Addition of 3% (v) neat diethylamine to the standard aqueous ammonia deprotection conditions allows clean and rapid one-step deprotection of 5′-[O,O-bis(pivaloyloxymethyl)] (POM)-protected VP oligonucleotides, minimizing side reactions and impurities, which broadly enhances the scope of VP oligonucleotide synthesis.Graphical abstractImage 1
       
  • Thioquinomycins A-D, novel naphthothiophenediones from the marine-derived
           Streptomyces sp. SS17F
    • Abstract: Publication date: Available online 5 September 2018Source: TetrahedronAuthor(s): Dashan Zhang, Yongjun Jiang, Jiaqi Li, Wanjing Ding, Zhe Chen, Zhongjun MaThioquinomycins A-D (1–4), four novel naphthothiophenediones were isolated from the rice-based medium of the marine-derived Streptomyces sp. SS17F. Their structures were elucidated by spectroscopic methods and HRESIMS data. The absolute configurations of all the compounds were elucidated by X-ray diffraction analysis, ECD and Mosher's method combined with 19F-NMR. Compounds 1–4 showed moderate cytotoxicity against NCI-H1975 with IC50 values from 17.5 to 50 μM. In addition, compounds 1–4 also exhibited inhibitory activities against PKCα and ROCK2 protein kinase.Graphical abstractImage 1
       
  • Enantioselective anti-Mannich reaction catalyzed by modularly
           designed organocatalysts
    • Abstract: Publication date: Available online 5 September 2018Source: TetrahedronAuthor(s): Swapna Konda, John C.-G. ZhaoA highly stereoselective method for achieving the anti-Mannich reaction of aldehydes and ketones with ethyl (4-methoxyphenylimino)acetate was realized using the modularly designed organocatalysts (MDOs) self-assembled from cinchona alkaloid derivatives and (R)-pyrrolidien-3-carboxylic acid in the reaction media. The desired anti-Mannich products were obtained in good to excellent yields (up to 93%), excellent diastereoselectivities (up to 99:1 dr), and good to high enantioselectivities (up to 99% ee).Graphical abstractImage 1
       
  • NbCl5 a multifunctional reagent for the synthesis of new halogenated
           aminoquinoline compounds through innovative one-pot reaction and the
           acidochromism effect
    • Abstract: Publication date: Available online 5 September 2018Source: TetrahedronAuthor(s): Giovanny Carvalho dos Santos, Vitor Fernandes Moreno, Paula Beatriz Oshiro, Luiz Carlos da Silva-FilhoThis paper describes an original one-pot way to synthesize nine new halogenated aminoquinoline derivatives using reactions conducted by niobium pentachloride. Subsequently, we describe an efficient and selective reduction reaction of nitroquinolines using niobium pentachloride and zinc, producing important compounds in the organic synthesis.The results showed that it is an important tool to synthesize these compounds, besides being time- and resources-saving and generating good yields. A quick study of acidochromism was performed.Graphical abstractAn efficient new method for aminoquinoline synthesis was developed using simple and readily available starting materials in mild conditions.Image 1
       
  • Efficient synthesis of alkynyl amides via aminocarbonylation of
           iodoalkynes
    • Abstract: Publication date: Available online 5 September 2018Source: TetrahedronAuthor(s): Péter Szuroczki, Borbála Boros, László KollárIodoethynylbenzene as iodoalkyne model compound was aminocarbonylated with tert-butylamine under carbon monoxide atmosphere in the presence of in situ palladium(0) catalysts. The formation of the unsaturated carboxamide (alkynyl amide) is always accompanied by that of the Glaser coupling product, diphenylbutadiyne. The yield of the amide-forming reaction was optimised by the systematic variation of the phosphine ligand, carbon monoxide pressure and temperature. The scope of the reaction was investigated by using various primary and secondary amines including amino acid methyl esters as N-nucleophiles.17α-(Iodoethynyl)-testosterone was also functionalised by using this methodology providing the corresponding 17α-(carboxamidoethynyl)-testosterone derivatives in up to 96% yields. The reaction was extended to 1-(iodoethynyl)cyclohex-1-ene and 1-iodohex-1-yne. Ethyl iodopropiolate gave the enamine type product by the addition of amine to the alkyne functionality which was formed from the iodoalkyne via deiodination under standard aminocarbonylation conditions. The bromo analogue, bromoethynylbenzene has shown lower reactivity than the corresponding iodo derivative.Graphical abstractImage 1
       
  • Pyrrolidine-carbamate based new and efficient chiral organocatalyst for
           asymmetric Michael addition of ketones to nitroolefins
    • Abstract: Publication date: Available online 5 September 2018Source: TetrahedronAuthor(s): Amarjit Kaur, Kamal Nain Singh, Esha Sharma, Shilpy, Poonam Rani, Sandeep Kumar SharmaThe novel ((S)-pyrrolidin-2-yl)methyl phenylcarbamate was synthesized and used as an efficient organocatalyst for the asymmetric Michael addition of cyclic/acyclic ketones to nitroolefins. Interestingly, the resulting Michael adducts were obtained in good to high yields (up to 96%) with excellent stereoselectivity (ee up to>99%, dr up to>99:1) without using any additive.Graphical abstractImage 1
       
  • Formation of substituted 2-iminooxazolidines via intermolecular
           1,2-addition / intramolecular N-vinylation using
           3-substituted-2-bromo-2-propen-1-ols as substrates
    • Abstract: Publication date: Available online 4 September 2018Source: TetrahedronAuthor(s): Heike Weischedel, Dietmar Schmidt, Jürgen Conrad, Uwe BeifussThe Cu2O-catalyzed reaction between equimolar amounts of easily available 3-substituted-2-bromo-2-propen-1-ols and dicyclohexyl carbodiimide in DMSO at 100 °C using K3PO4 as the base and in the absence of any additive exclusively delivers substituted 2-iminooxazolidines with yields up to 80%. The highly selective transformation is assumed to start with an intermolecular 1,2-addition, which is followed by an intramolecular N-vinylation. The products can also be obtained in the absence of Cu2O, albeit in lower yields.Graphical abstractImage 1
       
  • Atroposelective arylation of biaryls by C-H activation
    • Abstract: Publication date: Available online 4 September 2018Source: TetrahedronAuthor(s): Quentin Dherbassy, Joanna Wencel-Delord, Françoise ColobertAxial chirality of biaryls is found in natural products, bioactive molecules, ligands and catalysts. Thus, the atroposelective palladium-catalyzed C-H functionalization of chiral biaryl sulfoxides was extended to a direct arylation reaction, affording ortho-terphenyls bearing one atropisomeric axis. The high stereoselectivities, good yields and operational simplicity, along with the traceless character of the sulfoxide moiety allows access to a wide range of optically active o-terphenyls.Graphical abstractImage 1
       
  • Aliphatic hydroxylation and epoxidation of capsaicin by cytochrome P450
           CYP505X
    • Abstract: Publication date: Available online 31 August 2018Source: TetrahedronAuthor(s): Anna K. Migglautsch, Melissa Willim, Bettina Schweda, Anton Glieder, Rolf Breinbauer, Margit WinklerMicrobial cytochrome P450 enzymes (CYPs) are able to mimic the metabolism of human CYPs. One challenge is to identify the respective drug metabolites and to compare substrate specificities to those of the human enzymes. In this study, a class VIII self-sufficient CYP from Aspergillus fumigatus (CYP505X) and variants of this enzyme were heterologously expressed in E. coli. The substrate scope of the variants was determined using active pharmaceutical ingredients (APIs) and (hetero)cyclic compounds. Capsaicin – the active compound in chili peppers – was oxidized most efficiently (4.36 μM/min) in a whole cell mediated biotransformation. The products were isolated, purified and their structures elucidated by 1D and 2D NMR. The two major metabolites showed modifications on the lipophilic side chain. Specifically, capsaicin was hydroxylated at position 8 to give (E)-8-hydroxy-N-(4-hydroxy-3-methoxybenzyl)-8-methylnon-6-enamide and epoxidized at the double bond to give N-(4-hydroxy-3-methoxybenzyl)-5-(3-isopropyloxiran-2-yl)-pentanamide.Graphical abstractImage 1
       
  • Novel synthesis of 3-carboxamidolactam derivatives via palladium-catalysed
           aminocarbonylation
    • Abstract: Publication date: Available online 29 August 2018Source: TetrahedronAuthor(s): László Kollár, Attila TakácsAminocarbonylation of alkenyl and (hetero)aryl iodides using medium-sized 3-aminolactams as N-nucleophiles was carried out in the presence of in situ palladium(0) catalysts. While the iodoalkenes were converted to the corresponding carboxamide under mild reaction condition (1 bar of CO, 50 °C) by using Pd(OAc)2/PPh3 catalysts, the iodobenzene shown decreased reactivity (39% conversion after 2 days) under the similar reaction conditions in the presence of 3-aminoazepan-2-one. The reactivity of iodobenzene and other iodo(hetero)aromatic substrates was increased with 3-aminoazepan-2-one under high (40 bar) carbon monoxide pressure, but the chemoselectivity was shifted towards the 2-ketocarboxamides formed via double carbon monoxide insertion (except 2-iodopyridine). Changing triphenylphosphine to Xantphos, the expected carboxamides were chemoselectively formed in all cases when iodo(hetero)aryl substrates were used in the presence of all of the three 3-aminolactams under mild reaction conditions. The products synthesized in the reactions mentioned above were isolated in moderate to high yields.Graphical abstractImage 1
       
  • An acyclic enediyne anticancer compound attributed to a Bergman
           cyclization at physiological temperature
    • Abstract: Publication date: Available online 25 August 2018Source: TetrahedronAuthor(s): Baojun Li, Bing Duan, Jing Li, Mengsi Zhang, Yuan Yuan, Yun Ding, Aiguo HuEnediyne cytotoxic drugs have attracted much attention because of their unique structure and potent anticancer activity. However, acyclic enediynes are long considered as inactive at physiological temperature due to their long C1-C6 distance. By adjusting the steric bulkiness of the functional groups at the alkynyl termini and the electron-withdrawing effect at the ene moiety, herein, a simple acyclic enediyne was designed and synthesized to achieve the onset of thermal Bergman cyclization at physiological temperature in polar solvents. The spontaneous generation of diradical intermediates was confirmed through EPR analysis and further supported by spin trapping experiment, radical indicator experiment, and high resolution MS analysis. The reactive diradicals generated in aqueous media induced single and double stranded cleavage of DNA, and showed high cytotoxicity to Hela cells. The IC50 value of the enediyne compound is comparable to many clinical used anti-tumor agents.Graphical abstractAn acyclic enediyne functions possibly through spontaneous Bergman cyclization to induce DNA cleavage, inhibit cancer cell growth, and lead cancer cells to apoptosis pathway.Image 1
       
  • Diastereoselective Weitz-Scheffer epoxidation of levoglucosenone for the
           synthesis of isolevoglucosenone and derivatives
    • Abstract: Publication date: Available online 25 August 2018Source: TetrahedronAuthor(s): Edward T. Ledingham, Ben W. GreatrexHigh-yielding epoxidation conditions for the cellulose pyrolysis product (−)-levoglucosenone (LGO) and 3-aryl derivatives of LGO have been developed. The reaction of LGO with hydrogen peroxide/base is known to give a Baeyer-Villiger reaction, however, it was found that the reactions of LGO or derivatives with tert-butylhydroperoxide/base affords solely epoxides through the Weitz-Scheffer reaction. A critical parameter in the successful isolation of the epoxide from LGO was to avoid all contact with water or alcohols during the reaction and workup. The epoxide products were reacted under Wharton conditions affording allylic alcohols and subsequent oxidation led to isolevoglucosenone or 3-arylisolevoglucosenone derivatives. Previously unreported reactions on isolevoglucosenone were then investigated.Graphical abstractImage 1
       
  • Synthesis of new 1,2-dideoxy C-linked carbo-β-amino acids and
           α/β-peptides with 11/9-helix, helix-turn and helix-turn-helix structures
           
    • Abstract: Publication date: Available online 24 August 2018Source: TetrahedronAuthor(s): Ramesh Adepu, Marumudi Kanakaraju, Nagula Chandramouli, Purushotham P. Reddy, Gangavaram V.M. Sharma, Akella V.S. Sarma, Ajit C. KunwarThe present study describes the synthesis of new C-linked carbo-β-amino acids [β-Caa(1,2-ddx)], with a 1,2-dideoxy D-xylo furanoside side chain (a tetrahydro furan derivative). The stereochemistry at the newly created amine centers was determined by modified Mosher method. The (S)-β-Caa(1,2-ddx) prepared from d-mannose diacetonide were utilized for the synthesis of 1:1 α/β-peptides with L-Ala. The conformational analysis (NMR, MD and CD) revealed the presence of 11/9-helix, helix induced helix-turn (HT) and helix-turn-helix (HTH) in these peptides. These side chains with tetrahydrofuran ring facilitated the formation of robust helix, unlike some other side chains from earlier studies.Graphical abstractImage 1
       
  • Anti-pathogens constituents and novel ergosterol derivatives with the
           broad-spectrum germicidal substances from earthworm, Pheretima aspergillum
           
    • Abstract: Publication date: Available online 7 July 2018Source: TetrahedronAuthor(s): H.Q. Liu, J.Y. Gao, B.Y. Lv, Q.Q. Yang, K. Liu, W.P. YinAntimicrobial activity-guided isolation found a series of new compounds from Pheretima aspergillum. Novel structures were elucidated by NMR spectroscopic and HRMS analyses, whereas their absolute configurations were established by ORD and CD spectrometer. The further evaluation for antipathogens activities showed that broad-spectrum germicidal effects of novel ergosterol derivatives for compound II and III. Our data provide antimicrobial mechanistic insights by molecular docking.Graphical abstractNew natural products (Compounds I-IV) including one alkaloids (I), two ergosterol derivatives (II-III) and one alkyl oligoglycosides (IV) were isolated for the first time from annulata earthworm, Pheretima aspergillum.Image 1
       
 
 
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