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Published by Elsevier Homepage  [3184 journals]
  • Reusable shuttles for exchangeable functional cargos: Reversibly
           assembled, magnetically powered organocatalysts for asymmetric aldol
    • Abstract: Publication date: Available online 10 September 2019Source: TetrahedronAuthor(s): Carolina Mendoza, Augustin de la Croix, Paola Riente, Lluís Llorens, Javier de Mendoza, Miquel A. Pericàs A supramolecular approach has been followed to support adamantyl substituted proline organocatalysts onto the surface of magnetite nanoparticles decorated with a β-cyclodextrin motif. The resulting magnetic nanoparticles (ca. ∼10 nm diameter) were used as modular, magnetically recyclable catalysts in the asymmetric aldol reaction of aromatic aldehydes with cyclic ketones in water. The catalytic assemblies can be easily dismantled in organic media, and the recovered nanoparticles (magnetically powered chemical shuttles) re-complexed with another suitably substituted catalytic unit (replaceable functional cargo).Graphical abstractImage 1
  • Total synthesis of PGF2α and 6,15-diketo-PGF1α and formal synthesis of
           6-keto-PGF1α via three-component coupling
    • Abstract: Publication date: Available online 10 September 2019Source: TetrahedronAuthor(s): Taehyeong Kim, Sung Il Lee, Sejin Kim, Su Yong Shim, Do Hyun Ryu The asymmetric total synthesis of PGF2α and 6,15-diketo-PGF1α and formal synthesis of 6-keto-PGF1α from a common key intermediate are described. The key intermediate, which has a chiral cyclopentane backbone possessing suitable functional groups with required stereochemistry for both side chains, was prepared from (R)-4-silyloxy-2-cyclopentenone through a three-component coupling reaction. The Wittig reaction, Nozaki-Hiyama-Kishi (NHK) coupling and cross metathesis completed the synthesis of PGF2α, 6,15-diketo-PGF1α and 6-keto-PGF1α.Graphical abstractImage 1
  • (S)-(−)-Fluorenylethylchloroformate (FLEC); preparation using asymmetric
           transfer hydrogenation and application to the analysis and resolution of
    • Abstract: Publication date: Available online 9 September 2019Source: TetrahedronAuthor(s): Mohammad A. Amin, Michelle A. Camerino, Simon J. Mountford, Xiao Ma, David T. Manallack, David K. Chalmers, Martin Wills, Philip E. Thompson Fluorenylethylchoroformate (FLEC) is a valuable chiral derivatisation reagent that is used for the resolution of a wide variety of chiral amines. Herein, we describe an improved preparation of (S)-(−)-FLEC using an efficient asymmetric catalytic transfer hydrogenation as the key step. We also demonstrate the application of FLEC as a chiral Fmoc equivalent for chiral resolution, with facile deprotection, of tetrahydroquinaldines, and its capacity for inducing regioselective outcomes in nitration reactions.Graphical abstractImage 1
  • Corrigendum to “Isosteric expansion of the structural diversity of
           chiral ligands: Design and application of proline-based N,N′-dioxide
           ligands for copper-catalyzed enantioselective Henry reactions”
           [Tetrahedron 75 (2019) 130492]
    • Abstract: Publication date: Available online 9 September 2019Source: TetrahedronAuthor(s): En Gao, Meng Li, Lili Duan, Lin Li, Yue-Ming Li
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    • Abstract: Publication date: 27 September 2019Source: Tetrahedron, Volume 75, Issue 39Author(s):
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    • Abstract: Publication date: 27 September 2019Source: Tetrahedron, Volume 75, Issue 39Author(s):
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    • Abstract: Publication date: 27 September 2019Source: Tetrahedron, Volume 75, Issue 39Author(s):
  • Structural, photoelectrical and thermol properties of ultra-stable
           Benzo[ghi]perylene trimide dimer anion
    • Abstract: Publication date: Available online 5 September 2019Source: TetrahedronAuthor(s): Siyu Wu, Caihong Cheng, Wenlong Hou, Qizhe Li, Danyang Dong, Yongshun Gao, Lu Liu, Bo Liang, Haiquan Zhang Perylene diimide and its various derivatives tend to form stable anion radicals, which can usually form a variety of aggregates with special properties. Herein, we reported synthesis and properties of the benzo[ghi]perylene trimide and its anion radical π-bonded dimer. The dimer exhibited high stable in solid status and in most organic solvents, but conversion of L-type π-bonded dimer to face to face type π-bonded dimer or π-stacked oligomer occurs in dimethyl formamide solution. The temperature and crystallization influenced the π-bonded length in the dimer and the partial memory can be reserved and probed in solution at room temperature.Graphical abstractImage 1
  • Unique photochromism of two solid-emissive boron difluoride-based
           diarylethenes with isomeric structures
    • Abstract: Publication date: Available online 5 September 2019Source: TetrahedronAuthor(s): Haichuang Lan, Yaqian Li, Shuang Yuan, Shuzhang Xiao Two solid-emissive boron difluoride-based diarylethenes with isomeric structures are synthesized and the boron-difluoride chromophores are one part of the photoisomerization units in both diarylethenes. These two diarylethenes show similar fluorescent properties in the solid state as in dilute chloroform solutions because intermolecular planar π-π interactions are significantly alleviated as verified by their X-ray single crystal structures. However, only one of these two diarylethenes exhibits typical reversible absorption and fluorescence changes upon UV or visible light irradiation, and their diverse response to light irradiation is investigated by X-ray single crystal analysis and also DFT calculation. The investigation presented here provides valuable insight into the designing and development of diarylethene-based fluorescent switches in the solid state.Graphical abstractImage 1
  • Synthesis of polyunsaturated fatty boronic esters and their in vitro
           inhibition to HCT116 cell lines
    • Abstract: Publication date: Available online 5 September 2019Source: TetrahedronAuthor(s): Yongkai Yuan, Peng Chen, Shuaizhong Zhang, Xiang Lan, Zhuzhu Liu, Dongfeng Wang, Ying Xu, Xun Sun Five polyunsaturated fatty boronic esters (PUFB) were synthesized using a photoinduced decarboxylative borylation reaction from corresponding polyunsaturated fatty acids (PUFA) and in vitro anti-proliferation activity of these molecules on HCT116 cell lines was tested. The yield of the photoinduced decarboxylative borylation reaction was negatively correlated with the number of double bonds in PUFA. Additionally, application of vacuum to the reaction significantly improved the yield. All PUFBs showed anti-proliferation effect on HCT116 cell lines and the mixture of the 5 PUFBs showed higher toxicity than each individual PUFB. Again, the cytotoxicity was positively correlated with number of double bonds. Furthermore, PUFBs showed weaker anticancer activity than the corresponding PUFAs and this is tentatively attributed to the change of antioxidant potency and we categorize PUFBs to “secondary antioxidants”. We hope our findings deepen the understanding of photoinduced decarboxylative borylation reaction and provide further insights to the design of PUFA based bioactive molecules.Graphical abstractImage 1
  • Total synthesis of apios isoflavones and investigation of their tyrosinase
           inhibitory activity
    • Abstract: Publication date: Available online 5 September 2019Source: TetrahedronAuthor(s): Nana Asebi, Ken-ichi Nihei Apios isoflavone glucosides 1 and 2 were synthesized for the first time via Friedel–Crafts reaction, Bischler–Napieralski-type cyclization, and phase-transfer catalyzed glycosylation as the key steps. In addition, aglycones 4 and 5 and related natural isoflavone cajanin (6) were synthesized in short steps. Evaluation of the inhibitory activity of these compounds toward tyrosinase indicated that all the compounds were active. In particular, the half-maximal inhibitory concentration of compound 1 toward tyrosinase was measured to be 729 μM.Graphical abstractImage 1
  • Willgerodt-Kindler reaction at room temperature: Synthesis of thioamides
           from aromatic aldehydes and cyclic secondary amines
    • Abstract: Publication date: Available online 5 September 2019Source: TetrahedronAuthor(s): Arun D. Kale, Yogesh A. Tayade, Sachin D. Mahale, Rahul D. Patil, Dipak S. Dalal A simple method for the synthesis of thioamide derivatives in DMSO at room temperature and at 120 °C has been developed. Total 27 compounds were prepared under both conditions via a one-pot, three component reaction between substituted aromatic aldehydes, elemental sulfur powder, and cyclic secondary amines. By optimizing the mole ratio of sulfur powder and amines, we have successfully carried out Willgerodt-Kindler reaction of aromatic aldehydes at room temperature. At 120 °C, it is catalyst free reaction with lower reaction time whereas at room temperature, due to the additional amine molecule, Willgerodt-Kindler reaction of aromatic aldehydes is successfully carried out at room temperature. On gram-scale, the reaction is successfully attempted under both conditions with good yields.Graphical abstractImage 1
  • C+bond+cleavage+of+arylidene+Meldrum's+acid+and+malononitrile+derivatives&rft.title=Tetrahedron&rft.issn=0040-4020&">A transition metal free expedient approach for the CC bond cleavage of
           arylidene Meldrum's acid and malononitrile derivatives
    • Abstract: Publication date: Available online 4 September 2019Source: TetrahedronAuthor(s): Muthiah Suresh, Anusueya Kumari, Raj Bahadur Singh A transition metal free expedient approach for the CC bond cleavage of electron deficient alkenes such as arylidene Meldrum's acid and malononitrile derivatives are discussed. The CC bond of these compound were cleaved to benzoic acid in good yield at high temperature. Most importantly, with oxone in CH3CN/H2O at 45 °C or m-CPBA in DCM or NaClO2 in THF/H2O or PIDA in THF at room temperature furnished benzaldehyde derivatives selectively in excellent yields.Graphical abstractImage 1
  • Mn(III)acetate-mediated additions of active methylene compounds to
           bicyclic olefins: Synthesis of bicyclic olefin-fused dihydrofurans
    • Abstract: Publication date: Available online 4 September 2019Source: TetrahedronAuthor(s): Raşit Çalışkan, Bahadır Alabaş Bicyclic alkenes such as benzonorbornadiene, oxabenzonorbornadiene, norbornene, and norbornadiene were reacted with 1,3-cyclohexanedione and ethyl acetoacetate in the presence of Mn(OAc)3 and Cu(OAc)2. Except for the reaction of benzonorbornadiene and ethyl acetoacetate, dihydrofuran derivatives were the only products obtained. The formation of naphthalene derivatives was observed together with dihydrofuran in the aforementioned benzonorbornadiene/ethyl acetoacetate reaction. Additionally, the dihydrofuran product from the addition of ethyl acetoacetate to norbornadiene was slowly converted into epoxide derivative with air. The mechanism for the formation of the products is discussed.Graphical abstractImage 1
  • Inclusion abilities towards hexyne isomers by co-crystallization with
           extended V-shaped host molecule
    • Abstract: Publication date: Available online 1 September 2019Source: TetrahedronAuthor(s): Masatoshi Kawahata, Masahide Tominaga, Kousuke Fujimaru, Tadashi Hyodo, Kentaro Yamaguchi Disubstituted adamantane derivative possessing chloropyrazine (1) was synthesized and used as an extended V-shaped host molecule for the preparation of inclusion crystals containing hexyne isomers. The crystallization of 1 with 3-hexyne or 2-hexyne in chloroform provided co-crystals (1a, 1b) with 1:2 host:guest complexation stoichiometry, whereas guest-free crystals (1c) were produced in the case of 1-hexyne. In the co-crystals, the dimers built from 1 through CH···O interaction were arranged into a molecular network through multiple intermolecular interactions, and the guest molecules were accommodated within the cavity built from four molecules of 1. From the crystallization of equimolar binary mixtures of 3-hexyne or 2-hexyne and 1-hexyne in the presence of 1, co-crystals 1a and 1b were supplied, respectively. Competition experiments revealed that the selectivity order of 1 for the hexyne isomers was 3-hexyne and 2-hexyne ≫ 1-hexyne.Graphical abstractImage 1
  • Desymmetrization of meso-bisphosphates via rhodium catalyzed asymmetric
           allylic arylation
    • Abstract: Publication date: Available online 31 August 2019Source: TetrahedronAuthor(s): Reece Jacques, Alexander M.L. Hell, Robert D.C. Pullin, Stephen P. Fletcher The desymmetrization of meso-compounds allows for the unmasking of previously installed stereogenic centers, and quaternary centers are of special interest as they are frequently challenging to form with control in synthesis. Here, we report the desymmetrization of highly functionalized cyclic meso-bisphosphates via Rhodium-catalyzed enantioselective allylic arylation. The highly enantioselective introduction of functionalized (hetero)aryl moieties to a prostereogenic quaternary center generates three continuous stereogenic centers. Typical (hetero)arylboronic acids are tolerated in synthetically useful yields and excellent enantioselectivity.Graphical abstractImage 1
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    • Abstract: Publication date: 20 September 2019Source: Tetrahedron, Volume 75, Issue 38Author(s):
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    • Abstract: Publication date: 20 September 2019Source: Tetrahedron, Volume 75, Issue 38Author(s):
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    • Abstract: Publication date: 20 September 2019Source: Tetrahedron, Volume 75, Issue 38Author(s):
  • A solvent-dependent fluorometric dual-mode probe for Pd2+ and ClO− in
           living cells
    • Abstract: Publication date: Available online 30 August 2019Source: TetrahedronAuthor(s): Meipan Yang, Li Wang, Xin Leng, Yuan Zhang A solvent-dependent probe based on rhodamine was designed, and the sensing behaviors were investigated by spectral properties. Especially, the probe exhibited highly sensitive and selective fluorescence enhancement upon addition of Pd2+ in ethanol/PBS (2:8, v/v) and ClO− in DMSO/PBS (1:9, v/v) at physiological range with two kinds of mechanisms. Furthermore, the probe was applied for biological imaging which confirmed that it could be used for monitoring Pd2+ and ClO− in living cells with satisfying results.Graphical abstractImage 1
  • Synthetic access to 3,4-disubstituted pyroglutamic acid from tetramate
           derivatives from serine, allo-threonine and cysteine
    • Abstract: Publication date: Available online 29 August 2019Source: TetrahedronAuthor(s): Halima Bagum, Kirsten E. Christensen, Miroslav Genov, Alexander Pretsch, Dagmar Pretsch, Mark G. Moloney A route allowing the conversion of substituted tetramates to 3,4-disubstituted pyroglutamates, making use of Suzuki coupling on an enol mesylate, followed by reduction, is both general and fully stereoselective.Graphical abstractImage 1
  • Organocatalytic asymmetric [3+2]-cycloaddition of 3-isothiocyanato
           oxindoles with 1,3,5-trisubstituted-hexahydro-1,3,5-triazines to access
    • Abstract: Publication date: Available online 29 August 2019Source: TetrahedronAuthor(s): Chuan-Bao Zhang, Pei-Hao Dou, Yong You, Zhen-Hua Wang, Ming-Qiang Zhou, Xiao-Ying Xu, Wei-Cheng Yuan An efficient asymmetric [3 + 2]-cycloaddition reaction of 3-isothiocyanato oxindoles and formaldimines in-situ generated from 1,3,5-trisubstituted-hexahydro-1,3,5-triazines with a cinchona alkaloid-derived thiourea as the catalyst has been developed. A range of biologically important spiro-imidazolidinethione-oxindoles were obtained in excellent yields with good enantioselectivities (up to 99% yield and 93% ee).Graphical abstractImage 1
  • Efficient access to β- and γ-carbolines from a common starting material
    • Abstract: Publication date: Available online 29 August 2019Source: TetrahedronAuthor(s): Tran Quang Hung, Do Trung Hieu, Dinh Van Tinh, Ha Nam Do, Tuan Anh Nguyen Tien, Dang Van Do, Le Thanh Son, Ngoc Han Tran, Nguyen Van Tuyen, Vu Minh Tan, Peter Ehlers, Tuan Thanh Dang, Peter Langer Two efficient and practical approaches are reported for the synthesis of β- and γ-carboline derivatives from 3,4-dibromopyridine as a common starting material. The β-carbolines were prepared by site-selective Pd-catalyzed C–C coupling with o-bromophenylboronic acid and subsequent cyclization by double C–N coupling with amines. γ-Carbolines were prepared from the same starting material by C–N coupling with anilines and subsequent annulation by domino C–C/C–N coupling with o-bromophenylboronic acid.Graphical abstractImage 1
  • Tacamine-type alkaloids from Tabernaemontana bovina together with their
           configuration determination
    • Abstract: Publication date: Available online 28 August 2019Source: TetrahedronAuthor(s): Yang Yu, Mei-Fen Bao, Yi Wang, Ying Zeng, Xiang-Hai Cai Eleven undescribed tacamine type alkaloids, named tabercamines A–K were isolated from leaves of Tabernaemontana bovina, together with six known alkaloids. The planar structure of the undescribed alkaloids were determined by comprehensive spectroscopic data analysis. Their absolute configuration were established based on the combination of the electronic circular dichroism and single X-ray crystal diffraction analysis. The NMR rules (in acetone-d6) of identifying of the stereo-configuration at C-20/16 was established.Graphical abstractImage 1
  • Synthesis of non-symmetrical alkynylpyridines by chemoselective
           Sonogashira cross-coupling reactions
    • Abstract: Publication date: Available online 28 August 2019Source: TetrahedronAuthor(s): Rodisnel Perdomo Rivera, Peter Ehlers, Lars Ohlendorf, Marian Blanco Ponce, Eugenio Torres Rodríguez, Peter Langer 4-Bromo-2,3,5-trichloro-6-iodopyridine was studied as a new substrate in chemoselective Sonogashira reactions. This approach provides an efficient access to non-symmetrical mono-, di-, tri- and pentaalkynylated pyridines in good yields. Selected pentaalkynylated pyridines were studied with regard to their UV/Vis- and emission properties showing moderate to high fluorescence quantum yields.Graphical abstractImage 1
  • Rh(I)-catalyzed ring-opening of cyclobutanols via C–C bond activation:
           Synthesis of cis-olefin with a remote aldehyde
    • Abstract: Publication date: Available online 27 August 2019Source: TetrahedronAuthor(s): Yu Nie, Jianzhong Chen, Wanbin Zhang A Rh(I)-catalyzed ring-opening of cyclobutanols has been developed with ring opening products bearing cis-olefin and a remote aldehyde. Various substrates bearing different substituted aryl groups, heterocyclic groups and alkyl groups were compatible with the mild reaction conditions. A β-C elimination pathway was proposed based on the results of preliminary mechanistic studies.Graphical abstractImage 1
  • Synthesis of β-oxo carbonyl and thiocarbonyl compounds via
           basic sulfur abstraction
    • Abstract: Publication date: Available online 26 August 2019Source: TetrahedronAuthor(s): Saúl Silva, Christopher D. Maycock Sulfur abstraction from suitable thioesters represents a mild method for the formation of carbon-carbon bonds and the formation of 1,3-dicarbonyl compounds. A study of the scope and limitations of this reaction for the synthesis of these or mixed 1,3-carbonyl/thiocarbonyl compounds by a base promoted sulfur abstraction rearrangement is described. These reactions were typically very clean and the products were obtained in good yield (65–95%) in just 30 min. This method is particularly efficient for the introduction of thiocarbonyl containing groups. Thus, it constitutes a synthetic strategy for the generation of a new carbon-carbon bond and the regioselective preparation of mixed β-dicarbonyl compounds.Graphical abstractImage 1
  • Molecular structure and basic spectroscopic properties of
           3-selenocyanatoindole: An important reference compound in organoselenium
    • Abstract: Publication date: Available online 26 August 2019Source: TetrahedronAuthor(s): Atsuki Ikeda, Shahed Rana, Soichi Sato, Kazunori Hirabayashi, Masahiko Hada, Toshio Shimizu, Ken-ichi Sugiura Studies of the molecular structure and the basic spectroscopic properties of 3-selenocyanatoindole, an important reference compound in organoselenium chemistry, were carried out. Single-crystal diffraction analysis revealed that the selenocyanation of indole occurred at 3-position. The characteristic feature of its molecular structure is the perpendicularly connected SeCN group. Theoretical studies indicated that the SeCN group attached to arene rotates freely at room temperature and takes any conformation in the solid state depending on the packing effect. A hitherto unreported 77Se NMR spectrum of the title compound showed a large upfield shift that suggests the strong electron-donating nature of indole-3-yl.Graphical abstractImage 1
  • Transformation of aromatic bromides into aromatic nitriles with n-BuLi,
           pivalonitrile, and iodine under metal cyanide-free conditions
    • Abstract: Publication date: Available online 24 August 2019Source: TetrahedronAuthor(s): Ko Uchida, Hideo Togo Various aromatic nitriles could be obtained in good yields by the treatment of aryl bromides with n-butyllithium and then pivalonitrile, followed by the treatment with molecular iodine at 70 °C, without metal cyanides under transition-metal-free conditions. The present reaction proceeds through the radical β-elimination of imino-nitrogen-centered radicals formed from the reactions of imines and N-iodoimines under warming conditions. © 2019 Elsevier Science. All rights reserved.Graphical abstractImage 1
  • A highly sensitive fluorescence probe for thiophenol in living cells via a
           substitution-cyclization strategy
    • Abstract: Publication date: Available online 24 August 2019Source: TetrahedronAuthor(s): Linlin Yang, Yang Liu, Yanping Li, Hao Wang, Haihua Zhang, Jinhe Xu, Liguo Ji, Qingzhi Wang, Guangjie He A novel fluorescent probe 1 was synthesized for the detection of thiophenol on the basis of a unique thiophenol-mediated substitution-cyclization reaction. The probe 1 displayed 420-fold fluorescence intensity enhancement and highly selective and sensitive response for thiophenol over other competing sulfur species. This probe showed an excellent linear relationship in 10–140 μM and the low detection limit of 29 nM. The recognition mechanism of probe 1 toward PhSH was supported by the NMR spectrum and ESI-MS. Furthermore, the probe 1 was successfully applied for detection of thiophenol in living HepG2 cells.Graphical abstractImage 1
  • Regioselective bromination of arenes mediated by triphosgene-oxidized
    • Abstract: Publication date: Available online 23 August 2019Source: TetrahedronAuthor(s): Yingzhou Xu, Dufen Hu, Hui Zheng, David Mei, Zhaobo Gao This article first time describes triphosgene (BTC) as an oxidant while the non-toxic and easy-to-handle potassium bromide (KBr) as the source of bromine to the bromination reaction of aromatic substrates. The novel brominating protocol gives excellent para-regioselectivity of the alkoxyl/hydroxyl arenes and high yield, offering good potential of commercial scale applications. The mechanism of “Triphosgene oxidize bromide” was proposed.Graphical abstractThis article first time describes triphosgene (BTC) as an oxidant while the non-toxic and easy-to-handle potassium bromide (KBr) as the source of bromine to the bromination reaction of aromatic substrates. The novel brominating protocol gives excellent para-regioselectivity of the alkoxyl/hydroxyl arenes and high yield, offering good potential of commercial scale applications. The mechanism of “Triphosgene oxidize bromide” was proposed.Image 1
  • Base-free Pd-MOF catalyzed the Suzuki-Miyaura cross-coupling reaction of
           arenediazonium tetrafluoroborate salts with arylboronic acids
    • Abstract: Publication date: Available online 23 August 2019Source: TetrahedronAuthor(s): Yangyang Liu, Jie Wang, Tang Li, Zesheng Zhao, Wan Pang A convenient and environmental benign synthesis of biaryls has been demonstrated by a straightforward reaction catalyzed by the palladium-containing metal-organic framework (Pd-MOF) [Pd (2-pymo)2]n (2-pymo = 2-pyrimidinolate). A series of functionalized biaryl derivatives have been synthesized in good to excellent yields by the Suzuki-miyaura cross-couplings of sustainable arenediazonium salts with a variety of arylboronic acids and the reactions were catalyzed by the Pd-MOF using methanol as a benign solvent. Those base- and additive-free catalytic reactions proceeded smoothly under non-anhydrous and non-degassed condition. Such transformation avoided high reaction temperature, tolerated many functional groups and presented a wide substrate scope. The catalyst could be recovered by filtration and reused for four successive cycles before collapse of the MOF structure.Graphical abstractA convenient and environmental benign synthesis of biaryls has been demonstrated by a straightforward reaction catalyzed by the palladium-containing metal-organic framework (Pd-MOF) [Pd(2-pymo)2]n (2-pymo = 2-pyrimidinolate). Fonts or abstract dimensions should not be changed or altered.Image 1
  • Iodine/persulfate-promoted site-selective direct thiolation of quinolones
           and uracils
    • Abstract: Publication date: Available online 22 August 2019Source: TetrahedronAuthor(s): Danupat Beukeaw, Medena Noikham, Sirilata Yotphan A simple and general method for direct thiolation of 4-quinolones with disulfides or thiols under I2/K2S2O8 system has been developed. Under the optimal conditions, the C–S bond coupling can take place effectively with good to decent yields and excellent regioselectivity of the S-linked products. The established metal-free site-selective approach was also applicable to transform a range of uracil substrates to the thio-substituted products under mild conditions. Further transformation to the sulfone derivatives can be conveniently performed in one-pot. These easy-to-handle protocols represent a useful and interesting synthetic alternative with good substrate scope and functional group compatibility.Graphical abstractImage 1
  • Singlet oxygen mediated one pot synthesis of N-pyridinylamides via
           oxidative amidation of aryl alkyl ketones
    • Abstract: Publication date: Available online 21 August 2019Source: TetrahedronAuthor(s): Firdoos Ahmad Sofi, Rohit Sharma, S.N. Kavyasree, Sumi Aisha Salim, Pravin J. Wanjari, Prasad V. Bharatam An environmental friendly, efficient protocol has been realized for the synthesis of N-pyridinylamides via copper catalyzed oxidative amidation of aryl alkyl ketones with 2-aminopyridines. This one pot protocol involves chemo selective cleavage of C (O)–C bond in the presence of singlet oxygen. The reaction conditions are simple, tolerates wide range of substrates and the products were formed in good to excellent yields. This method offers a moderate improvement over the earlier successful attempts in generating N-pyridinylamides.Graphical abstractImage 1
  • Cu(0)/Selectfluor system-catalyzed intramolecular Csp2-H/Csp2-H
           cross-dehydrogenative coupling (CDC)
    • Abstract: Publication date: Available online 21 August 2019Source: TetrahedronAuthor(s): Hanyang Bao, Xiaojun Hu, Jian Zhang, Yunkui Liu A Cu(0)/Selectfluor system-catalyzed intramolecular Csp2-H/Csp2-H bond cross-dehydrogenative coupling of 2-aryloxybenzaldehydes is described. A variety of substituted xanthone derivatives are synthesized in moderate to excellent yields. Reaction can also be extended to the synthesis of 9H-thioxanthen-9-one 10,10-dioxide and phenanthridin-6(5H)-ones, respectively.Graphical abstractImage 1
  • AgOTf-catalyzed reaction of sulfonyl hydrazones with ynamides led to
           stereoselective synthesis of α-amino alkenyl-substituted hydrazone
    • Abstract: Publication date: Available online 21 August 2019Source: TetrahedronAuthor(s): Ziping Cao, Shikun Yan, Changyin Zhao, Xuejun Sun, Laijin Tian, Xin Meng A novel method for the synthesis of α-amino alkenyl-substituted hydrazone derivatives was disclosed through silver-catalyzed reaction of sulfonyl hydrazones with ynamides. The present method features mild conditions, high stereoselectivity and good yields. The proposed mechanism involves silver-mediated generation of a keteniminium ion intermediate to facilitate the stereoselective addition of hydrazones in the presence of K2CO3, while pyrazole ring could not be constructed under the current conditions.Graphical abstractImage 1
  • Unified synthesis of diverse building blocks for application in the
           discovery of bioactive small molecules
    • Abstract: Publication date: Available online 20 August 2019Source: TetrahedronAuthor(s): Scott Rice, Daniel J. Cox, Stephen P. Marsden, Adam Nelson The synthesis of large numbers of diverse molecular scaffolds with controlled molecular properties is a significant challenge in synthetic organic chemistry. A modular unified synthesis was developed, and was exploited in the synthesis of sixteen diverse three-dimensional scaffolds. The approach exploited two cyclisation precursors to be converted, using a toolkit of cyclisation reactions, into spirocyclic and fused-ring scaffolds. Remarkably, Pd-catalysed aminoarylation of substituted N-Boc-hex-5-enylamine cyclisation precursors to yield N-Boc piperidine-containing scaffolds was successful which was ascribed to a significant Thorpe−Ingold effect. Computational property analysis showed that the decorated scaffolds are shape-diverse, and enable diverse lead-like chemical space to be targeted.
  • Reactions of alkyl 4-hydroxybut-2-ynoates with arenes under
           superelectrophilic activation with triflic acid or HUSY zeolite:
           Alternative propargylation or allenylation of arenes, and synthesis of
    • Abstract: Publication date: Available online 19 August 2019Source: TetrahedronAuthor(s): Natalia A. Devleshova, Stanislav V. Lozovskiy, Aleksander V. Vasilyev Reactions of alkyl 4-aryl(or 4,4-diaryl)-4-hydroxybut-2-ynoates [Ar(H or Ar')(OH)C4–C3≡C2–CO2Alk] with arenes under the action of triflic acid TfOH or HUSY zeolite result in the formation of two main compounds, aryl substituted furan-2-ones or products of propargylation of electron rich arenes. Key reactive intermediates in these transformations are the corresponding O,O-diprotonated forms of starting butynoates, Ar(H or Ar')(+OH2)C4–C3≡C2– C(=O+H)(OAlk), dehydration of which gives rise to mesomeric propargyl-allenyl cations Ar(H or Ar')(OH)4C+–C3≡C2–C(=O+H)(OAlk) ↔ Ar(H or Ar')(OH)4C = C3 = 2C+–C(=O+H)(OAlk), having two electrophilic centers on the carbons C4 and C2 respectively. Reactions of these species with arenes at C4 lead to products of arene propargylation, alternatively, reactions at C2 result in allenylation of arenes, followed by further transformation into furan-2-ones. Using quantum chemical calculations by the DFT method, it has been shown that the reactivity of such propargyl-allenyl cations is mainly explained by orbital factors. Plausible reaction mechanism is discussed.Graphical abstractImage 1
  • Generating cis-aza-diaryl and triaryl ethers via organoBrønsted acid
           catalysed aza-Darzens chemistry
    • Abstract: Publication date: Available online 19 August 2019Source: TetrahedronAuthor(s): Sean P. Bew, Simon J. Coles, Mateusz B. Pitak, Wim T. Klooster, Polly-Anna Ashford, Victor Zdorichenko We report the efficient combination of SNAr and organic Brønsted acid catalysis protocols for the construction of cis-aziridine-derived biaryl and triaryl ethers. Using aza-Darzens chemistry mono-cis-aziridine-biaryl and bis-(cis-aziridine)-triaryl ethers have been generated; these motifs have significant potential as easily synthesised, functionalised precursors of a glycopeptide backbone.Graphical abstractImage 1
  • A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and
           their use in amidoalkylation of hydrogen, heteroatom, and carbon
    • Abstract: Publication date: Available online 19 August 2019Source: TetrahedronAuthor(s): Anastasia A. Fesenko, Alexander N. Yankov, Anatoly D. Shutalev A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.Graphical abstractImage 1
  • Caryophyllene sesquiterpenes, chromones and 10-membered macrolides from
           the marine-derived fungus pseudopestalotiopsis sp. PSU-AMF45
    • Abstract: Publication date: Available online 17 August 2019Source: TetrahedronAuthor(s): Haryadi N. Putra, Vatcharin Rukachaisirikul, Saowanit Saithong, Souwalak Phongpaichit, Sita Preedanon, Jariya Sakayaroj, Sarinya Hadsadee, Siriporn Jungsuttiwong Three new caryophyllene sesquiterpenes, pestalotiopsins I–K, one new chromone, pseudopestalone, and one new 10-membered macrolide, decarestrictine Q, were isolated from the fermentation broth of the marine-derived fungus Pseudopestalotiopsis sp. PSU-AMF45 along with twelve known compounds. Their structures were identified by spectroscopic data including 1D and 2D NMR. The absolute configuration of pestalotiopsin I was assigned based on single-crystal X-ray diffraction crystallography whereas that of the secondary alcohol moiety in pestalotiopsin J was established by Mosher's method. For pseudopestalone, the absolute configuration was determined by ECD spectrum associated with TD-DFT calculation. The antimicrobial activity of the isolated compounds was evaluated.Graphical abstractImage 1
  • Stereoselective synthesis of a new methyl-substituted inositol derivative
    • Abstract: Publication date: Available online 16 August 2019Source: TetrahedronAuthor(s): Latif Kelebekli, Ilknur Atlı The stereoselective synthesis of methyl-substituted inositol derivative is described. Diene diacetate which is a key compound was first prepared via three steps starting from 2-methyl-p-benzoquinone. Osmium-catalyzed regio- and stereoselective dihydroxylation of diene diacetate afforded cis-diol diasetate, which then produced tetra acetate via acetylation with Ac2O-pyridine. Oxidation and acetylation of the other alkene moiety in the compound gave a hexaacetate compound stereoselectively. Finally, the acetate groups were removed by NH3 leading to formation of the desired new methyl-substituted inositol derivative having a muco-inositol-type stereochemical pattern in the six-membered ring. Spectroscopic methods were used for characterization of all synthesized compounds.Graphical abstractImage 1
  • Synthesis of fluorinated acyclic nucleoside phosphonates with
           5-azacytosine base moiety
    • Abstract: Publication date: Available online 16 August 2019Source: TetrahedronAuthor(s): Karel Pomeisl, Marcela Krečmerová, Radek Pohl, Robert Snoeck, Graciela Andrei With respect to the strong antiviral activity of (S)-1-[3-hydroxy-2-(phosphonomethoxy)propyl]-5-azacytosine various types of its side chain fluorinated analogues were prepared. The title compound, (S)-1-[3-fluoro-2-(phosphonomethoxy)propyl]-5-azacytosine (FPMP-5-azaC) was synthesised by the condensation reaction of (S)-2-[(diisopropoxyphosphoryl)methoxy)-3-fluoropropyl p-toluenesulfonate with a sodium salt of 5-azacytosine followed by separation of appropriate N [1] and O [2] regioisomers and ester hydrolysis. Transformations of FPMP-5-azaC to its 5,6-dihydro-5-azacytosine counterpart, amino acid phosphoramidate prodrugs and systems with an annelated five-membered imidazole ring, i.e. imidazo [1,2-a][1,3,5]triazine derivatives were also carried out. 1-(2-Phosphonomethoxy-3,3,3-trifluoropropyl)-5-azacytosine was prepared from 5-azacytosine and trifluoromethyloxirane to form 3,3,3-trifluoro-2-hydroxypropyl-5-azacytosine which was treated with diisopropyl bromomethanephosphonate followed by deprotection of esters. Antiviral activity of all newly prepared compounds was studied. FPMP-5-azaC diisopropyl ester inhibited the replication of herpes viruses with EC50 values that were about three times higher than that of the reference anti-HCMV drug ganciclovir without displaying cytotoxicity.Graphical abstractImage 1
  • First synthesis of both enantiomers of pseudohygrophorone A12, an
    • Abstract: Publication date: Available online 14 August 2019Source: TetrahedronAuthor(s): Yuzuki Yamamoto, Yusuke Ogura, Hidenori Watanabe, Hirosato Takikawa Pseudohygrophorone A12, a highly oxygenated cyclohexenone derivative isolated from Hygrophorus abieticola, exhibits anti-fungal activity against several phytopathogenic fungi and oomycete. The first synthesis of both enantiomers of pseudohygrophorones A12 was accomplished starting from an optically active sulfoxide. In our approach, the diastereoselective Michael−aldol cascade reaction was featured as the key step.Graphical abstractImage 1
  • Erythrina alkaloids from leaves of Erythrina arborescens
    • Abstract: Publication date: Available online 14 August 2019Source: TetrahedronAuthor(s): Bing-Jie Zhang, Wen-Na Xiao, Jing Chen, Mei-Fen Bao, Johann Schinnerl, Qi Wang, Xiang-Hai Cai Continued interest in Erythrina alkaloids resulted in the isolation of 38 alkaloids including 7 undescribed ones from the leaves of Erythrina arborescens Roxburgh. Among the new compounds, erythrivarines H-I were two dimeric alkaloids, while others were Erythrina alkaloid glucosides. Dimeric Erythrina alkaloids and monomers, turcomanidine and isoboldine, showed medium xanthine oxidase inhibition.Graphical abstractImage 1
  • Dialkoxymethano[60]fullerenes as electron acceptors in thin-film organic
           solar cells
    • Abstract: Publication date: Available online 10 August 2019Source: TetrahedronAuthor(s): Mohammed Y. Suleiman, Yue Ma, Takafumi Nakagawa, Hiroshi Ueno, Yutaka Matsuo This study presents the synthesis, characterization, and electrochemical properties of four new dialkoxymethanofullerenes, as well as their performance in organic solar cells (OSCs) devices. Dialkoxymethanofullerenes were synthesized in 27%–32% yield by thermolysis of dialkoxyoxadiazolines and reaction with C60 under reflux in toluene. The prepared compounds were then characterized and used for the first time as electron-acceptor materials in thin-film bulk heterojunction OSCs with PBTZT-stat-BDTT-8 as the electron donor material. The devices made with ethoxy-hexyloxymethanofullerene and methoxy-hexyloxymethanofullerene exhibited optimal power conversion efficiencies (PCEs) of 3.79% and 4.65%, with open-circuit voltage of 0.832 and 0.831 V, respectively. In contrast, the devices made with ethoxy-ethoxymethanofullerene and methoxy-ethoxymethanofullerene exhibited very low PCEs of
  • DDQ-promoted direct C–H amination of ethers with N-alkoxyamides under
           visible-light irradiation and metal-free conditions
    • Abstract: Publication date: Available online 8 August 2019Source: TetrahedronAuthor(s): Yan Zhang, Lei Wang, Zhiming Wang, Wei Chen A C(sp3)–N bond forming reaction between N-alkoxyamides and simple ethers has been developed. In the presence of commercially available 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ), a variety of N-methoxyamides and ethers undergo this transformation smoothly to deliver the corresponding products in good yields under visible-light irradiation and metal-free conditions at room temperature.Graphical abstractImage 1
  • Straightforward synthesis of 4,5-bifunctionalized 1,2-oxazinanes via Lewis
           acid promoted regio- and stereo-selective nucleophilic ring-opening of
           3,6-dihydro-1,2-oxazine oxides
    • Abstract: Publication date: Available online 24 May 2019Source: TetrahedronAuthor(s): Xiu-Rong Huang, Yu-Mei Zhang, Ting-Biao Wan, Piao Zhang, Xiu-Xiu Zhang, Fang-Ming Wang, Defeng Xu, Mei-Hua Shen, Hua-Dong Xu Functionalized 1,2-oxazinanes are interesting and valuable heterocycles with potential applications in synthetic and medicinal chemistry. A straightforward strategy for quick access to unprecedented trans-4-hydroxyl-5-azido/cyano/amino 1,2-oxazinanes are developed: N-COR 3,6-dihydro- 1,2-oxazine oxides are prepared with ease from related dihydro- 1,2-oxazines and opened by nucleophiles TMSN3, TMSCN and aryl/alkyl amines. Appropriate Lewis acid catalysts are found playing a vital role for both reaction rate and regioselectivity. The N-COR group can be removed under mild conditions to provide highly desirable NH 1,2-oxazinanes inaccessible via previous methods.Graphical abstractLewis acid catalysis enabled highly selective ring-opening of 3,6-dihydro-1,2-oxazine oxide with nucleophiles gives rise to valuable functionalized 1,2-oxazinanes with readily removable N-COR group.Image 1
  • A lifetime journey into the world of chemistry
    • Abstract: Publication date: Available online 21 May 2019Source: TetrahedronAuthor(s): Léon GhosezABSTRACTThe professional life of the author has been a fascinating journey through the magnificent landscapes of synthetic organic chemistry. A friendly editor invited him to share a few of these travel memories.This review is thus a (very) personal and (totally) prejudiced account of the author’s research in organic chemistry. It describes the work of his associates and coworkers at UCLouvain in Belgium or at IECB in France.All schemes only deal with work which was done in both research groups. The names of the coworkers will appear in the references. The author apologizes to those coworkers whose work has not been cited but he had to sail within his pages’ allocation. As will be seen, many areas of organic synthesis have been visited. The results of the research were put into perspective with the status of the field when the research was undertaken. Obviously several of these fields of research have dramatically expanded later on; credit could not be given here to these important developments. However, when available, some recent reviews will be cited to give a flavour of the most recent work. Thus, the reader should not expect to read a “classical” review of a topical subject. The purpose of this paper is merely the sharing of professional experiences of a modest but enthusiastic teacher and researcher.
  • Controlled and diastereoselective synthesis of α-(3-hydroxy-2
    • Abstract: Publication date: Available online 1 April 2019Source: TetrahedronAuthor(s): Muthumanickam Shenbagapushpam, Thennila Muthukumar, Muthu Mareeswaran Paulpandian, Arun Prasath Lingam Kandhapalam, Selvakumar Kodirajan An efficient synthesis of non-natural, diastereoselective, α-hydroxyoxoindolin appended β-aminoester derivatives has been demonstrated from unprotected Morita-Baylis-Hillman (MBH) adducts of oxindole via simple aza-Michael addition strategy. The judicious choice of sodium hydride and bulky 2,4,6-triisopropylbenzenesulphonamide provided a controlled and diastereoselective addition products with MBH adducts of oxindole for the first time.Graphical abstractImage 1
  • Synthesis of chroman-4-one and indanone derivatives via silver catalyzed
           radical ring opening/coupling/cyclization cascade
    • Abstract: Publication date: Available online 29 July 2019Source: TetrahedronAuthor(s): Qiang Liu, Guanqun Xie, Qiang Wang, Zhendong Mo, Chen Li, Shujiang Ding, Xiaoxia Wang A variety of chroman-4-one and indanone derivatives were conveniently synthesized from readily available cyclopropanols and alkenyl aldehydes via a silver catalyzed radical ring-opening/coupling/cyclization cascade. The reaction proceeded under mild and neutral conditions with broad substrate scope and afforded the desired products in moderate to good yields. A probable mechanism for the cascade reaction was also proposed.Graphical abstractImage 1
  • Novel biferrocene-based phosphoramidite ligands: The combination of a
           rather unexplored chiral backbone and a privileged ligand scaffold
    • Abstract: Publication date: Available online 20 June 2019Source: TetrahedronAuthor(s): W. Kimpe, P. Janssens, K. Bert, S. Wackens, J.L. Goeman, J. Van der Eycken A small library of novel chiral monodentate phosphoramidite ligands, characterized by a dihydroazepine-biferrocene backbone was prepared. In order to obtain this biferrocene substructure, a mild and efficient homocoupling was developed. This allowed to synthesize the dihydroazepine ligand precursor and the phosphoramidite ligands with good overall yields and high enantiomeric excess. These ligands were successfully tested in a rhodium(I)-catalyzed hydrogenation of activated olefins.Graphical abstractImage 1
  • Rapid decoloration and acidichromism of photochromic
    • Abstract: Publication date: Available online 22 July 2019Source: TetrahedronAuthor(s): Bin Li, Zipei Sun, Yan Zhai, Jianlan Jiang, Yaodong Huang, Jiben Meng Pyranoquinoline, with its light-sensitive fragment and coordination node, provides an ideal matrix for the development of multi-functional photochromic compounds. This paper presents the synthesis and photochromic properties of 3,3-diaryl-3H-pyrano[3,2-f]quinoline derivatives QP1-QP8. All exhibited good photochromism under UV light irradiation followed by biexponential kinetic decay in the dark at ambient temperature. Their photochromic processes were reversible, and acidichromism was observed to occur in solution. The fading speeds of QP2 and QP6 were higher than those of their known naphthopyran counterparts, whereas the decoloring speeds of the six other compounds were all over an order of magnitude higher than those of QP2 and QP6. The synthesized pyranoquinolines exhibited very good fatigue resistance both in solution and the solid state. Compared to other pyranoquinolines, the optical densities of QP2 and QP6, i.e., the compounds with 2,4-dimethoxylphenyl and 1-naphthyl, were enhanced dramatically. For all the synthesized pyranoquinolines, a distinct bathochromic shift was observed with increasing solvent polarity. The structure-property relationship of the pyranoquinolines was revealed through the single-crystal X-ray analysis of QP1 and QP7.Graphical abstractImage 1
  • Bicarbazole/nitrogen heterocycle based bipolar host materials for
           efficient green phosphorescent organic light-emitting diodes
    • Abstract: Publication date: Available online 29 June 2019Source: TetrahedronAuthor(s): Yue Liu, Jiangnan Zhu, Yi Chen, Wenting Liang, Haitao Zhou, Jinhai Huang, Zhenyuan Xia, Jianhua Su In this paper, three novel bipolar host materials, 9,9′-Diphenyl-6-(4-pyridinyl)-3,3′-bicarbazole(BCz4Py), 9,9′-Diphenyl-6-(3-pyridinyl)-3,3′-bicarbazole(BCz3Py) and 9,9′-Diphenyl-6-(5-pyrimidinyl)-3,3′-bicarbazole(BCz5Pm), were synthesized by incorporation of bicarbazole as donor with pyridine/pyridimide based N-hexahydroxy nitric heterocycle as acceptor units. The photophysical, thermal and electrochemical properties of these three materials were fully investigated. These compounds all exhibited superior thermal stability with high glass-transition temperature (Tg > 130 °C) and decomposition temperature (Td > 400 °C). Appropriate HOMO (highest occupied molecular orbitial) -LUMO (lowest unoccupied molecular orbital) levels and and triplet energy (2.74–2.75 eV) of these compounds make them suitable hosts for green iridium pohosphor Ir(ppy)3 in phosphorescent organic light emitting devices (PhOLEDs). Among them, the BCz3Py hosted device exhibited outstanding performance with maximum external quantum efficiency (EQE) of 14.9%, maximum current efficiency (CE) of 49.9 cd/A, and maximum power efficiency (PE) of 29.1 lm/W, suggesting that BCz3Py is a promising bipolar material for high-efficiency green PhOLEDs.Graphical abstractImage 1
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