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  • Synthesis of Stilbene-Quinone Hybrids through Heck Reactions in PEG-400
    Synthesis (IF 2.650) Pub Date : 2017-08-28
    Demidoff, Felipe C., de Souza, Fabrícia P., Netto, Chaquip D.

    Styrenes were coupled with 3-iodolawsone in PEG-400 at 90 °C, leading stereoselectively to (E)-stilbene-quinone hybrids through Heck reactions. The best reaction conditions were found to be the use of NaOH (3 equiv) and 10 mol% of palladium acetate at 90 °C for 15 minutes. The chemical yields of the Heck reactions using styrenes with electron-withdrawing groups (65–98%) were greater than styrenes bearing electron-donating groups (7–32%) on the aromatic ring. In particular, the chemical yields of Heck reactions involving nitrostyrenes were the best ones observed.

    更新日期:2017-08-29
  • Synthesis of the Tripeptide Antibiotic Resormycin
    Synthesis (IF 2.650) Pub Date : 2017-08-28
    Kaduskar, Rahul D., Pinto, Andrea, Scaglioni, Leonardo, Musso, Loana, Dallavalle, Sabrina

    A short and efficient synthesis of resormycin, a metabolite of Streptomyces platensis MJ953-SF5 with herbicidal and antifungal activity, is described. The key step in our synthetic approach is a late-stage stereospecific dehydration of a β-hydroxy amino acid to install the Z-olefin. Because of the modular nature of the synthesis, access to analogues for biological evaluation is readily available.

    更新日期:2017-08-29
  • Copper-Catalyzed C–N Bond Exchange of N-Heterocyclic Substituents around Pyridine and Pyrimidine Cores
    Synthesis (IF 2.650) Pub Date : 2017-08-28
    Tao, Sheng, Ji, Enhui, Shi, Lei, Liu, Ning, Xu, Liang, Dai, Bin

    A copper-catalyzed transfer N-heteroarylation strategy using a C–N bond exchange reaction is described. This reaction accommodates a wide range of pyridine and pyrimidine rings bearing halogen atoms, which have wide utility for subsequent transformations. This method provides a direct and operationally simple approach for modifying complex molecules by the exchange of N-heterocyclic substituents.

    更新日期:2017-08-29
  • Recycled Pd/C-Catalyzed Heck Reaction of 2-Iodoanilines under Ligand-Free Conditions
    Synthesis (IF 2.650) Pub Date : 2017-08-28
    Zhou, Xiao-Yu, Chen, Xia, Wang, Liang-Guang

    Recyclable Pd/C-catalyzed Heck reaction of 2-iodoanilines with acrylate has been developed. The reaction occurred readily in 1,4-dioxane using Pd/C (10 wt%) as catalyst under ligand-free conditions, and the cross-coupling products were obtained with medium to high yield. Gram-scale reactions and recycling of the catalyst were also demonstrated.

    更新日期:2017-08-29
  • Catalyst- and Solvent-Free Addition of the P–H Species to Alkenes and Alkynes: A Green Methodology for C–P Bond Formation
    Synthesis (IF 2.650) Pub Date : 2017-08-28
    Gusarova, Nina K., Chernysheva, Nataliya A., Trofimov, Boris A.

    Traditional methods for C–P bond formation via direct addition of P–H species to unsaturated compounds are usually implemented in the presence of base and metal catalysts or radical initiators in various organic solvents. During the last five years, a novel efficient and general catalyst/initiator- and solvent-free version of the hydrophosphination and hydrophosphinylation of multiple C–C bonds with H-phosphines and their chalcogenides has begun to develop and it is attracting growing attention. This approach corresponds to the recently emerged pot-, atom-, and step-economy (PASE) green paradigm. This review covers the literature on the synthesis of useful and in-demand organophosphorus compounds via catalyst- and solvent-free addition of P–H species to alkenes and alkynes.

    更新日期:2017-08-29
  • Recent Advances in Transition-Metal-Catalyzed, Directed Aryl C–H/N–H Cross-Coupling Reactions
    Synthesis (IF 2.650) Pub Date : 2017-08-28
    Henry, Martyn C., Mostafa, Mohamed A. B., Sutherland, Andrew

    Amination and amidation of aryl compounds using a transition-metal-catalyzed cross-coupling reaction typically involves prefunctionalization or preoxidation of either partner. In recent years, a new class of transition-metal-catalyzed cross-dehydrogenative coupling reaction has been developed for the direct formation of aryl C–N bonds. This short review highlights the substantial progress made for ortho-C–N bond formation via transition-metal-catalyzed chelation-directed aryl C–H activation and gives an overview of the challenges that remain for directed meta- and para-selective reactions.

    更新日期:2017-08-29
  • Recent Developments in the Deoxyfluorination of Alcohols and Phenols: New Reagents, Mechanistic Insights, and Applications
    Synthesis (IF 2.650) Pub Date : 2017-08-28
    Hu, Wen-Li, Hu, Xiang-Guo, Hunter, Luke

    This short review describes the development of new reagents and methods for the deoxyfluorination of phenols and alcohols during the period of 2011 to 2017. Important advances in the mechanistic understanding of these processes are discussed. The continuing importance of deoxyfluorination chemistry for the synthesis of valuable target molecules is highlighted through case studies including examples of 18F-radiosynthesis and the preparation of exotic multifluorinated compounds.

    更新日期:2017-08-29
  • Phenol Oxidative Dearomatization of Modified Nucleoside Templates: A Simple Access to the C7-Spiroannulated Octosyl Acid Framework
    Synthesis (IF 2.650) Pub Date : 2017-08-28
    Mullapudi, Venkannababu, Bhogade, Ravindra B., Deshpande, Mukund V., Ramana, Chepuri V.

    Phenol oxidative dearomatization and cyclization has been executed successfully on nucleoside templates to synthesize C7-spiroannulated perhydrofuropyran nucleosides and C6-spiroannulated perhydrofurofuran nucleosides as novel analogues of octosyl acid and related peptidyl nucleosides.

    更新日期:2017-08-29
  • An Update on Direct C–H Bond Functionalization of Nitrogen-Containing Fused Heterocycles
    Synthesis (IF 2.650) Pub Date : 2017-08-25
    Aziz, Jessy, Piguel, Sandrine

    This report highlights the recent advances in direct C–H bond functionalization of 5,5- and 6,5-fused heterocycles containing at least two nitrogen atoms. Besides C–C bond formation, C–N, C–S, C–P, and C–Si bonds can also be created via a metal-catalyzed process. Some examples, where a C–H functionalization approach was applied for the synthesis of drug candidates, will be presented as well.

    更新日期:2017-08-26
  • Synthesis of Penta-2,4-dienenitriles by the Horner–Wadsworth–Emmons Olefination of Enones
    Synthesis (IF 2.650) Pub Date : 2017-08-24
    Bencke, Carlos E., Marangoni, Mário A., Camargo, Adriano F., Fantinel, Cassio A., Bonacorso, Helio G., Martins, Marcos A. P., Zanatta, Nilo

    Three new series of compounds, 5-alkoxy-3-(trifluoromethyl)penta-2,4-dienenitriles, 5-(phenylthio)-3-(trifluoromethyl)penta-2,4-dienenitriles, and ethyl 4-alkoxy-2-(cyanomethylene)but-3-enoates, obtained from the olefination reaction of the respective enones with diethyl cyanomethylphosphonate via the Horner–Wadsworth–Emmons olefination are reported. All products were obtained as single regioisomers; however, the composition of the stereoisomers changed according to the enone substituents. A study based on 1H and 13C NMR chemical shifts, 1H–19F and 13C–19F NMR coupling constants, 1H NMR signal integrals, and HSQC, HMBC, and NOESY experiments was performed in order to assign the structure and percentage of each stereoisomer obtained.

    更新日期:2017-08-25
  • Zincation and Magnesiation of Functionalized Silylated Cyano­hydrins Using TMP-Bases
    Synthesis (IF 2.650) Pub Date : 2017-08-24
    Castelló-Micó, Alicia, Knochel, Paul

    Polyfunctional silylated cyanohydrins are readily magnesiated or zincated with TMPMgCl·LiCl or TMP2Zn·2MgCl2·2LiCl leading to the corresponding metallated derivatives. These Mg- or Zn-derivatives react with various electrophiles such as benzylic bromides, allylic bromides, acid chlorides, aldehydes, NCCO2Et, or MeSO2SMe. Subsequently, TBAF-deprotection provides the corresponding keto or 1,2-diketo derivatives.

    更新日期:2017-08-25
  • Recyclable [Ce(l-Pro)2]2 (Oxa) used as Heterogeneous Catalyst: One-Pot Synthesis of 2,3-Dihydroquinazolin-4(1H)-ones in Ethanol
    Synthesis (IF 2.650) Pub Date : 2017-08-24
    Katla, Ramesh, Chowrasia, Rakhi, da Silva, Caren D. G., de Oliveira, Aline R., dos Santos, Beatriz F., Domingues, Nelson L. C.

    [Ce(l-Pro)2]2 (Oxa) was used as a recyclable heterogeneous catalyst under mild conditions for the preparation of 2-aryl-2,3-dihydroquinazolin-4(1H)-one derivatives. The one-pot protocol proceeds in ethanol using anthranilamide with several aldehydes at 50–55 °C. The catalyst can be recycled and reused three cycles without significant loss of catalytic activity.

    更新日期:2017-08-25
  • Recent Advances on the Application of Electrocyclic Reactions in Complex Natural Product Synthesis
    Synthesis (IF 2.650) Pub Date : 2017-08-24
    Bian, Ming, Li, Lekai, Ding, Hanfeng

    The electrocyclic reaction is one of the most powerful tools for the construction of complex polycyclic scaffolds in a highly stereocontrolled fashion. In this review, recent advances in its application in the total synthesis of representative natural products are discussed, with the aim of providing a complement to existing reviews.

    更新日期:2017-08-25
  • Synthesis of Functionalized Cyclopentene Derivatives through Gold-Catalyzed Reaction of Stabilized Vinyldiazo Compounds and Styrenes
    Synthesis (IF 2.650) Pub Date : 2017-08-23
    López, Enol, Lonzi, Giacomo, López, Luis A.

    The reaction of alkenyldiazo compounds with styrene derivatives in the presence of [Au(IPr)(MeCN)][SbF6] provided cyclopentene derivatives resulting from a formal [3+2] cycloaddition reaction as major products. This reaction outcome stands in marked contrast to that previously observed for other olefinic derivatives. From a mechanistic point of view, this process would involve the initial generation of a highly electrophilic alkenylgold carbene intermediate, which would be subsequently involved in a stepwise carbocationic process.

    更新日期:2017-08-24
  • Synthesis and Bioactivity of Novel N-Benzylic and N-Phenethylic Ephedrine Derivatives
    Synthesis (IF 2.650) Pub Date : 2017-08-23
    Ellwart, Mario, Höfner, Georg, Gerwien, Aaron, Wanner, Klaus T., Knochel, Paul

    A range of N-benzylic and N-phenethylic ephedrine derivatives were prepared in a one-pot procedure starting from the two enantiomers of ephedrine using the Potier reagent, and a polyfunctional aryl- or benzylic organozinc halide. The biological activity in indatraline MS Binding Assays addressing hDAT, hNET and hSERT was determined and discussed.

    更新日期:2017-08-24
  • Palladium-Catalysed Cross-Coupling of Benzylammonium Salts with Boronic Acids under Mild Conditions
    Synthesis (IF 2.650) Pub Date : 2017-08-23
    Türtscher, Paul L., Davis, Holly J., Phipps, Robert J.

    Herein, we give a full account of the development of the palladium­-catalysed cross-coupling of benzylammonium salts with boronic acids. A range of benzylamine-derived quaternary ammonium salts can be coupled with boronic acids under relatively mild conditions. Our optimization has identified ligands that can be used to chemoselectively cross-couple at the ammonium in the presence of chlorides. We demonstrate that intramolecular palladium-catalysed C–H activation is also a viable pathway for the putative benzyl-Pd(II) intermediate obtained upon oxidative addition and have optimised this to obtain fluorene in good yield.

    更新日期:2017-08-24
  • The Transient Directing Group Strategy: A New Trend in Transition-Metal-Catalyzed C–H Bond Functionalization
    Synthesis (IF 2.650) Pub Date : 2017-08-23
    Zhao, Qun, Poisson, Thomas, Pannecoucke, Xavier, Besset, Tatiana

    In recent years, the C–H bond activation field has known very fast expansion offering valuable synthetic tools. Consequently, the quest for new approaches to afford atom- and step-economical processes has driven the scientific community to imagine original strategies. In this context, the direct functionalization of substrates by a transition-metal-catalyzed C–H bond activation using a transient directing group has emerged as a promising approach. This short review focuses on the major progress made in this field to provide to the reader an overview of the recent advances.

    更新日期:2017-08-24
  • Base-Promoted Synthesis of O-Aryl/Alkyl N,N-Dimethylthiocarbamates Starting from Inexpensive and Environmentally Benign Disulfide
    Synthesis (IF 2.650) Pub Date : 2017-08-22
    Dong, Zhi-Bing, Wang, Ming, Zhu, Hui, Liu, Xing, Chang, Cai-Zhu

    A series of O-aryl (alkyl) N,N-dimethylthiocarbamates were synthesized in good yields (70–77%) by reacting substituted phenols or alkyl alcohol with inexpensive, stable, and environmentally benign tetramethylthiuram disulfide (TMTD) in the presence of NaH. By avoiding use of the toxic and corrosive N,N-dialkylthiocarbamoyl chloride, the method provides a green and facile preparation for some important precursors of potentially biologically reactive compounds.

    更新日期:2017-08-23
  • Domino Reactions of 1-Aroyl-3,4-dihydroisoquinolines with α,β-Unsaturated Aldehydes
    Synthesis (IF 2.650) Pub Date : 2017-08-22
    Matveeva, Maria D., Borisova, Tatiana N., Titov, Alexander A., Anikina, Lada V., Dyachenko, Svetlana V., Astakhov, Grigorii S., Varlamov, Alexey V., Voskressensky, Leonid G.

    An efficient synthesis of pyrrolo[2,1-a]isoquinolines by a domino reaction from a variety of 3,4-dihydropyrrolo[2,1-a]isoquinolines and α,β-unsaturated aldehydes in the absence of catalyst in good yields under microwave irradiation, is reported.

    更新日期:2017-08-23
  • Synthesis of 3,3-Disubstituted 2-Oxindoles by Deacylative Alkylation of 3-Acetyl-2-oxindoles
    Synthesis (IF 2.650) Pub Date : 2017-08-22
    Ortega-Martínez, Aitor, Molina, Cynthia, Moreno-Cabrerizo, Cristina, Sansano, José M., Nájera, Carmen

    An innovative and efficient monoalkylation and nonsymmetrical 3,3-dialkylation of oxindoles has been achieved. First, the monoalkylation of 3-acetyl-2-oxindoles can be performed in good yields under mild reaction conditions using alkyl halides and benzyltrimethylammonium hydroxide (Triton B) as base at room temperature. This methodology is applied to construct the synthetically challenging compound 1,3-dimethyl-2-oxindole. Subsequent deacylative alkylation (DaA) of the alkylated 3-acetyl-2-oxindoles with alkyl halides takes place efficiently using LiOEt or by conjugate addition with electron-deficient alkenes in the presence of Triton B at room temperature under argon, affording the corresponding unsymmetrically 3,3-disubstituted 2-oxindoles. This simple methodology has been applied to the synthesis of precursors of horsfiline, esermethole, physostigmine, and phenserine alkaloids.

    更新日期:2017-08-23
  • Tf2NH-Catalyzed 1,6-Conjugate Addition of Vinyl Azides with p-Quinone Methides: A Mild and Efficient Method for the Synthesis of β-Bis-Arylamides
    Synthesis (IF 2.650) Pub Date : 2017-08-22
    Rathod, Jayant, Sharma, Brijesh M., Mali, Pramod S., Kumar, Pradeep

    Tf2NH-catalyzed tandem 1,6-conjugate addition/Schmidt type rearrangement using vinyl azides and p-quinone methides to access a variety of β-bis-arylated amides is reported. The method is quick, efficient, mild, and high yielding with broad substrate scope.

    更新日期:2017-08-23
  • Copper-Catalyzed C–S Cross-Coupling Reaction: S-Arylation of Arylthioureas
    Synthesis (IF 2.650) Pub Date : 2017-08-22
    Zhu, Hui, Liu, Xing, Chang, Cai-Zhu, Dong, Zhi-Bing

    A simple and efficient copper-catalyzed S-arylation of aryl­thioureas was developed. Arylthioureas were smoothly converted into aryl-isothioureas with good yield by copper-catalyzed S-arylation. The features of this method include the use of a ligand-free catalyst, good yield, short reaction time, and broad substrate scope. The method provides a facile and convenient preparation of some potentially biologically active compounds.

    更新日期:2017-08-23
  • Reactions of Arynes Involving Transition-Metal Catalysis
    Synthesis (IF 2.650) Pub Date : 2017-08-22
    Feng, Minghao, Jiang, Xuefeng

    Arynes are important building blocks for introducing aromatic rings into molecules and they are frequently utilized in syntheses. Historically, arynes were generated under harsh conditions and this limited their use. Arynes can now be generated under milder conditions, e.g. from 2-(trimethylsilyl)phenyl triflate, and utilized in transition-metal­ catalyzed reactions such as [2+2+2] reactions, insertion into σ-bonds, cascade cyclizations and C–H activation reactions. This short review focuses on transition-metal-catalyzed reactions relevant to aryne intermediates generated from 2-(trimethylsilyl)phenyl triflates and other aryne precursors.

    更新日期:2017-08-23
  • Synthesis and Properties of Nitrogen-Containing Curved Heterosuperbenzene
    Synthesis (IF 2.650) Pub Date : 2017-08-16
    Shi, Yubai, Li, Cheng, Ma, Shaohua, Zhang, Yin

    A novel nitrogen-functionalized curved superbenzene was prepared via oxidative cyclodehydrogenation of a suitable hexaarylbenzene precursor under mild conditions. The spectroscopic and electrochemical properties are detailed here and compared with those of permethoxylated hexa-peri-hexabenzocoronene. The crystal structure analysis confirmed that the molecule has an unequal ‘double-concave’ aromatic core due to the inclusion of a pyrimidine subunit and the steric encumbrance of the methoxy groups at the periphery.

    更新日期:2017-08-16
  • Asymmetric Desymmetrization of Substituted Cyclohexadienones by Rhodium-Catalyzed Conjugate Hydrosilylation and Theoretical Calculations of Its Mechanistic Aspects
    Synthesis (IF 2.650) Pub Date : 2017-08-15
    Naganawa, Yuki, Ito, Jun-ichi, Kawagishi, Mayu, Nishiyama, Hisao

    Asymmetric desymmetrization was demonstrated by means of transition-metal-catalyzed conjugate reduction with hydrosilanes as reductants. Chiral rhodium-bis(oxazolinyl)phenyl complexes [Rh(Phebox-R)] were found to be effective catalysts for conjugate hydrosilylation of differently γ,γ-disubstituted cyclohexadienones to provide the corresponding product with chiral quaternary centers. The mechanistic consideration was also performed by theoretical calculation. These attempts provided information about i) the initial activation of Rh(III) complex into Rh(I) species assisted by hydrosilanes, ii) the complete catalytic cycle, and iii) an explanation of the asymmetric induction and the difference of the structure of cyclohexadienones in enantioselectivity.

    更新日期:2017-08-15
  • Desymmetrization of Hepta-1,6-dien-4-ol by a Highly Stereo­selective Tandem Prins–Ritter Cyclization: Access to New THP Acetamides
    Synthesis (IF 2.650) Pub Date : 2017-08-14
    Glachet, Thomas, Fache, Fabienne, Pelotier, Béatrice, Piva, Olivier

    Prins–Ritter cyclization performed from hepta-1,6-dien-4-ol and various aldehydes, promoted by bismuth(II) triflate, afforded N-(tetrahydropyranyl)acetamides in moderate to high yields. Subsequent Wacker-type oxidation using Dess–Martin periodinane (DMP) delivered the corresponding ketones.

    更新日期:2017-08-15
  • Axially Chiral Shape-Persistent Encapsulating Agents
    Synthesis (IF 2.650) Pub Date : 2017-08-11
    Míguez-Lago, Sandra, Cid, María Magdalena

    In this review is presented the results of investigations during the last two decades on molecular recognition processes, mainly chiral host–guest systems insofar as they deal with intermolecular recognition events. Attention is devoted to those systems involving chiral hosts whose chirality does not arise from the presence of a chiral center and that possess a defined cavity to accommodate guests. Thus, the scope of this short review is restricted to chiral containers in which size, shape, and functionality are critical aspects, while those examples involving chirality transfer processes are excluded. The systems covered are those with axial chirality, including helical chirality, in which the chirality, that can be inherent or induced by steric interactions, originates from the 3D helical array of substituents. More specifically, the focus is on both macrocycles that bear open cavities and molecular cages with more enclosed voids.

    更新日期:2017-08-12
  • 5,6,7,8-Tetrahydronaphthalen-1-amine as Precursor for Thiazolidi­nones and Benzothiazepinones: Synthesis and Atropisomeric Relationship
    Synthesis (IF 2.650) Pub Date : 2017-08-10
    Drawanz, Bruna B., Zimmer, Georgia C., Rodrigues, Leticia V., Nörnberg, Andressa B., Hörner, Manfredo, Frizzo, Clarissa P., Cunico, Wilson

    The one-pot reaction of 5,6,7,8-tetrahydronaphthalen-1-amine, mercaptoacetic acid, and arenealdehydes having strong and weak electron-withdrawing groups gave the corresponding 1,3-thiazolidin-4-ones (47–70%). When arenealdehydes bearing strong and weak electron-donating groups were used as precursors, the 1,4-benzothiazepin-2-ones were obtained (30–72%) by p-TsOH catalysis. All compounds are unknown and were characterized by GC-MS and NMR techniques, and available crystals by X-ray diffraction studies. The atropisomerism phenomenon was observed in several 1,3-thiazolidin-4-ones as confirmed by VTNMR method. The Tc was established as 332 K and the energy required for the interconversion of one atrop­isomer into another is around 16.8 kcal·mol–1. Chemical quantum calculation and NOESY displayed that more stable isomer has the tetrahydro­naphthalene portion below the five-ring plane. Only a small difference between isomers (–0.21 to –0.84 kcal·mol–1) was observed by calculated energy.

    更新日期:2017-08-11
  • Synthesis of Glycosyl Azides and Their Applications Using CuAAC Click Chemistry to Generate Bis- and Tris(triazolyl)glycosyl Derivatives
    Synthesis (IF 2.650) Pub Date : 2017-08-10
    Shamim, Anwar, Vasconcelos, Stanley N. S., de Oliveira, Isadora Maria, Reis, Joel S., Pimenta, Daniel C., Zukerman-Schpector, Julio, Stefani, Hélio A.

    2,3-Unsaturated C-(triazolyl)glycosyl acetates have been synthesized from 3,4,6-tri-O-acetyl-d-glucal using C-glycosylation and click chemistry and were then used in a palladium-catalyzed Tsuji–Trost type allylic azidation reaction to afford the corresponding regioisomeric glucal-azide derivatives. Copper-catalyzed azide-alkyne cycloaddition (CuAAC) reactions with these glucal-based allylic azides using CuI as the catalyst, led to the corresponding glucal-based bis(triazole) derivatives. Performing further functional group modification and another click (CuAAC) reaction with each of these bis(triazolyl) glycosyl derivatives afforded tris(triazolyl)glycosyl derivatives. Two libraries of regioisomeric bis(triazole) derivatives and a small library of regioisomeric tris(triazole) derivatives of glucal were then synthesized using different alkynes.

    更新日期:2017-08-11
  • Pd-catalyzed Auto-Tandem Cascades Based on N-Sulfonylhydrazones: Hetero- and Carbocyclization Processes
    Synthesis (IF 2.650) Pub Date : 2017-08-10
    Barroso, Raquel, Cabal, María P., Valdés, Carlos

    The Pd-catalyzed cross-coupling between N-tosylhydrazones and organic halides is a powerful method for the creation of C–C bonds. This transformation has been included recently in cascade processes in which the same catalyst promotes various independent catalytic steps, a process known as auto-tandem catalysis. This strategy proves to be very useful for the construction of relatively complex carbo- and heterocyclic structures, as well as for the generation of molecular diversity. This short review will cover the different Pd-catalyzed auto-tandem reactions­ involving N-tosylhydrazones organized by the bond-forming sequence: C–C/C–N and C–C/C–C. Some examples of related tandem reactions leading to acyclic compounds are also highlighted.

    更新日期:2017-08-11
  • Visible-Light-Induced Trifluoromethylation of Highly Functionalized Arenes and Heteroarenes in Continuous Flow
    Synthesis (IF 2.650) Pub Date : 2017-08-09

    We report a continuous-flow protocol for the trifluoromethylation of arenes, heteroarenes, and benzofused heterocycles. This photoredox methodology relies on the use of solid sodium trifluoromethanesulfinate (CF3SO2Na) as the trifluoromethylating agent and the iridium complex [Ir{dF(CF3)ppy}2](dtbpy)]PF6 as the photoredox catalyst. A diverse set of highly functionalized heterocycles proved compatible with the methodology, and moderate to good yields were obtained within 30 minutes of residence time.

    更新日期:2017-08-10
  • Synthesis of α-Amino Esters via α-Nitro or α-Oxime Esters: A Review
    Synthesis (IF 2.650) Pub Date : 2017-08-09

    This review is an in-depth survey of the reported synthetic approaches for the preparation of racemic α-amino esters via the reduction of α-nitro or α-oxime ester intermediates. Accordingly, it describes the many pathways that have been designed to prepare such intermediates­. This includes synthesis starting with α-nitroacetates, dialkyl malonates, acetoacetates, diethyl oxalates as well as [2+3] or [2+4] cycloadditions using, respectively, alkyl carbonocyanidate N-oxides or alkyl 2-nitrosoacrylates. This review also contains the description of a myriad of side reactions which can occur when working with α-nitro esters­.

    更新日期:2017-08-10
  • Vinylation of Iododifluoromethylated Alcohols via a Light-Promoted Intramolecular Atom-Transfer Reaction
    Synthesis (IF 2.650) Pub Date : 2017-08-07

    A method for the synthesis of gem-difluorohomoallylic alcohols by the substitution of iodine in the iododifluoromethyl group by a vinyl fragment is described. The reaction proceeds via an intramolecular iodine atom transfer followed by β-elimination. The reaction is performed in the presence of an iridium photocatalyst, fac-Ir(ppy)3, and triphenylphosphine under irradiation with light-emitting diodes.

    更新日期:2017-08-07
  • The Palladium-Catalyzed Heteroarylation of Adamantylalkyl Amines with Dihalogenopyridines: Scope and Limitations
    Synthesis (IF 2.650) Pub Date : 2017-08-07

    Palladium-catalyzed heteroarylation of adamantylalkyl amines characterized by different steric hindrances at the amino group was carried out using 2,3-, 2,5-, 2,6-, and 3,5-dihalogenopyridines. The dependence of the results of the coupling on the nature of the halogen atoms (bromine, chlorine), their position in the pyridine ring, and on the structure of adamantylalkyl amines was investigated. The application of dichloropyridines or bromochloropyridines was shown to be advantageous over the use dibromopyridines in many cases. Selective substitution of bromine atom in positions 3 and 5 in the presence of chlorine atom in position 2 of the pyridine ring was observed. The possibility of N,N-diheteroarylation of adamantane-containing amines with 2,5-dihalogenopyridines was shown, and diamination of 2,6- and 3,5-dihalogenopyridines was demonstrated.

    更新日期:2017-08-07
  • Recent Advances in Nitrogen–Nitrogen Bond Formation
    Synthesis (IF 2.650) Pub Date : 2017-08-07

    Over the last decade, N–N bond formation as a synthetic strategy has emerged as a powerful key step in the construction of highly valuable heterocycles from easily obtained materials. This review focuses on recent methods used to build N–N bonds, classified by intra- and intermolecular reactions with various types of N–X (O, C, N, H) bond cleavage.

    更新日期:2017-08-07
  • 1,3,4-Oxadiazole and Heteroaromatic-Fused 1,2,4-Triazole Synthesis­ Using Diverted Umpolung Amide Synthesis
    Synthesis (IF 2.650) Pub Date : 2017-08-07

    Umpolung Amide Synthesis (UmAS) has emerged as a superior alternative to conventional amide synthesis methods based on carbonyl electrophiles in a range of situations, particularly when epimerization-prone couplings are prescribed. In an unanticipated development during our most recent studies, we discovered that diacyl hydrazide products from UmAS were not formed as intermediates when using an acyl hydrazide as the amine acceptor. This resulted in a new preparation of 1,3,4-oxadiazoles from α-bromonitroalkane donors. We hypothesized that a key tetrahedral intermediate in UmAS was diverted toward a more direct pathway to the heterocycle product rather than through formation of the diacyl hydrazide, a typical oxadiazole progenitor. In studies reported here, diversion to 1,2,4-triazole products is described, a behavior hypothesized to also result from an analogous tetrahedral intermediate, but one formed from heteroaromatic hydrazine acceptors.

    更新日期:2017-08-07
  • Copper-Catalyzed C–S Bond Formation via the Cleavage of C–O Bonds in the Presence of S8 as the Sulfur Source
    Synthesis (IF 2.650) Pub Date : 2017-08-03

    Useful and applicable methods for one-pot and odorless synthesis of unsymmetrical and symmetrical diaryl sulfides via C–O bond activation are presented. First, a new efficient procedure for the synthesis of unsymmetrical sulfides using the cross-coupling reaction of phenolic esters such as acetates, tosylates, and triflates and with arylboronic acid or triphenyltin chloride as the coupling partners is reported. Depending on the reaction, S8/KF or S8/NaOt-Bu system is found to be an effective source of sulfur in the presence of copper salts and in poly(ethylene glycol) as a green solvent. Then, the synthesis of symmetrical diaryl sulfides from phenolic compounds by using S8 as the sulfur source and NaOt-Bu in anhydrous DMF at 120 °C under N2 is described. By these protocols, the synthesis of a variety of unsymmetrical and symmetrical sulfides become easier than the available protocols in which thiols and aryl halides are directly used for the preparation of the sulfides.

    更新日期:2017-08-04
  • Metal-Catalyzed Isomerization of 5-Heteroatom-Substituted Isoxazoles­ as a New Route to 2-Halo-2H-azirines
    Synthesis (IF 2.650) Pub Date : 2017-08-03

    A convenient gram-scale method for the preparation of 2-halo-2H-azirine-2-carboxylic acid esters, thioesters and amides via metal-catalyzed isomerization of 5-heteroatom-substituted 4-haloisoxazoles is developed. The formation of the esters and amides is efficiently catalyzed by Rh2(Piv)4, while FeCl2·4H2O is the catalyst of choice for the synthesis of the thioesters. In addition, rhodium catalysis is successfully applied in the synthesis of azirine-2-carboxylates from non-halogenated 5-alkoxyisoxazoles.

    更新日期:2017-08-04
  • Synthesis of Fluoropyrrolidines and (Fluoroalkyl)pyrrolidines
    Synthesis (IF 2.650) Pub Date : 2017-08-03

    Pyrrolidines and their derivatives are of great interest in medicinal chemistry and organic synthesis. Fluoropyrrolidines and (fluoroalkyl)pyrrolidines have been utilized in the preparation of medicinal drugs and also as organocatalysts. The synthesis of such compounds is achieved through the fluorination of pyrrolidine derivatives or by multistep synthesis from already containing fluoroalkyl precursors.

    更新日期:2017-08-04
  • Synthesis of Novel Polyazinyl-Substituted Triazolopyridines from [1,2,3]Triazolo[1,5-a]pyridines
    Synthesis (IF 2.650) Pub Date : 2017-08-02

    A series of 7-azinyl-substituted triazolopyridines and 3-(6-azi­nyl-substituted 2-pyridyl)triazolopyridines were synthesized by addition of the corresponding 3-substituted 7-lithiotriazolopyridine to pyrimidine, pyrazine, pyridazine, and 1,3,5-triazine respectively, followed by hydrolysis and oxidation.

    更新日期:2017-08-03
  • The Friedel–Crafts Reaction of Indoles with Michael Acceptors Catalyzed by Magnesium and Calcium Salts
    Synthesis (IF 2.650) Pub Date : 2017-08-02

    Friedel–Crafts alkylation of indole and its derivatives with a variety of electron-deficient alkenes catalyzed by Mg and Ca salts has been studied. The dependence of the results on the nature of the starting olefins, substituents on indole, and Michael acceptors, as well as on the composition of the Lewis acid is discussed. High yields of the addition products were achieved in the addition of indole to β,γ-unsaturated α-keto esters and coumarin derivatives, some nitroolefins, and arylidenemalonates. Reactions involving arylidenemalonates were found to be the most versatile and smooth, the best yields reached 92%. Among the Mg and Ca salts tested, magnesium iodide (MgI2) proved to be the most appropriate catalyst in the addition to various unsaturated carbonyl compounds, while calcium triflimide [Ca(NTf2)2] efficiently catalyzed the addition to nitroolefins.

    更新日期:2017-08-03
  • Practical Preparation of Octa- and Tetrabromoperylene Diimides and Derivatives Thereof
    Synthesis (IF 2.650) Pub Date : 2017-08-02

    A mild synthesis of fully brominated perylene dianhydride and diimides in one step from easily available unsubstituted precursors is presented. The partial reduction of ortho-bromo substituents with hydrazine hydrate allowed for a gram-scale synthesis of a valuable intermediate, 1,6,7,12-tetrabromoperylene diimide. Several new twisted fully core-substituted perylene diimide derivatives having sulfur, nitrogen, or oxygen substituents were synthesized using regioselective nucleophilic substitution reactions.

    更新日期:2017-08-03
  • Palladium-Catalyzed Copper-Free Sonogashira Coupling of 2-Bromoarylcarbonyls: Synthesis of Isobenzofurans via One-Pot Reductive Cyclization
    Synthesis (IF 2.650) Pub Date : 2017-08-02

    Palladium-catalyzed copper-free Sonogashira coupling of 2-bromocarbonyls is presented. This method afforded the 2-alkynylaryl carbonyls, useful synthons for the accomplishment of many carbocyclic and heterocyclic motifs. Significantly, the strategy was extended to the one-pot synthesis of isobenzofurans via reduction followed by intramolecular 5-exo-dig cyclization.

    更新日期:2017-08-03
  • Triflic Anhydride Promoted Intramolecular Cyclization of N-Aryl Cinnamides: Access to Polysubstituted Quinolin-2(1H)-ones
    Synthesis (IF 2.650) Pub Date : 2017-08-02

    A facile and efficient synthesis of polysubstituted quinolin-2(1H)-ones is developed via intramolecular cyclization of readily available N-aryl cinnamides promoted by triflic anhydride in N,N-dimethyl trifluoroacetamide (DTA) under mild conditions.

    更新日期:2017-08-03
  • Organocatalytic Asymmetric Synthesis of 2,3′-Connected Bis-Indolinones by Mannich Reactions of N-Acetylindolin-3-ones with Isatin N-Boc Ketimines
    Synthesis (IF 2.650) Pub Date : 2017-08-01

    A highly diastereo- and enantioselective Mannich reaction of N-acetylindolin-3-ones with isatin N-Boc ketimines to form 2,3′-connected bis-indolinones is developed employing a low loading of a readily available bifunctional thiourea catalyst. The asymmetric synthesis connects two indolinones via a vic-diamine unit and generates two neighboring stereocenters.

    更新日期:2017-08-02
  • Sc(OTf)3-Catalyzed Oligomerization of Indole: One-Pot Synthesis of 2-[2,2-Bis(indol-3-yl)ethyl]anilines and 3-(Indolin-2-yl)indoles
    Synthesis (IF 2.650) Pub Date : 2017-08-01

    Oligomerization of substituted indoles and N-methylindoles was investigated in the presence of catalytic amounts of scandium triflate in dichloromethane. Two types of indole oligomer, 2-[2,2-bis(indol-3-yl)ethyl]anilines and 3-(indolin-2-yl)indoles were obtained based on the substituent on indole ring. This study constitutes the first example of Sc(OTf)3-catalyzed oligomerization of indoles and gave good yield of 2-[2,2-bis(indol-3-yl)ethyl]anilines and 3-(indolin-2-yl)indoles.

    更新日期:2017-08-02
  • A Short and Scalable Synthesis of Orthogonally Protected Bis(aminomethyl)malonic Acid: Access to Bioactive Macrocyclic Peptides
    Synthesis (IF 2.650) Pub Date : 2017-08-01

    A short and scalable process for the preparation of multi-gram quantities of orthogonally protected bis(aminomethyl)malonic acid in good yield from readily available starting material is described. These orthogonally protected amino acids are important building blocks to make peptides based drugs, glycoconjugates, and in the total synthesis of peptide natural products. The newly developed route has only six steps with an overall yield of 27%, which involves nucleophilic attack of a malonate on an imide as one of the key steps.

    更新日期:2017-08-02
  • Recent Advances in the Synthesis of Hydrogenated Azocine-Containing­ Molecules
    Synthesis (IF 2.650) Pub Date : 2017-08-01

    This review covers recent advances in synthesis of azocine-containing systems. The most approaches towards azocines are discussed.

    更新日期:2017-08-02
  • Palladium-Catalyzed Regio- and Stereoselective Hydrosulfonation of Propiolate Esters
    Synthesis (IF 2.650) Pub Date : 2017-07-31

    An efficient palladium-catalyzed addition reaction of alkyl- and arylsulfonic acids to propiolate esters to yield alkenyl sulfonates is demonstrated. The formation of alkenyl sulfonates is highly regio- and stereoselective with favorable yields of up to 95%, and two of the alkenyl sulfonates are utilized for a Sonogashira cross-coupling reaction to produce (Z)-1,3-enynoates.

    更新日期:2017-08-02
  • Pd/Indanone-Based Ligands: An Efficient Catalyst System for Ullmann­-Type, Suzuki–Miyaura, and Mizoroki–Heck Cross-Coupling Reactions with Aryl Tosylates and Aryl Halides
    Synthesis (IF 2.650) Pub Date : 2017-07-31

    2-Hydroxyindan-1-ones have been efficiently synthesized and successfully applied as ligands in Pd-catalyzed Ullmann type, Suzuki–Miyaura, and Mizoroki–Heck cross-coupling reactions with aryl tosylates and aryl halides. The ligands are air- and moisture-stable and have shown high catalytic activity with Pd(OAc)2 in these cross-coupling reactions. The system tolerates a variety of functional groups in the product and can be re-used at least three times with maximum efficiency.

    更新日期:2017-08-02
  • Improved Synthesis of Symmetrical 2,5-Diarylimidazoles by One-Pot Palladium-Catalyzed Direct Arylation Tailored on the Electronic Features of the Aryl Halide
    Synthesis (IF 2.650) Pub Date : 2017-07-31

    Two methods for the one-pot synthesis of 2,5-diarylimidazoles by palladium-catalyzed direct C–H arylation of 1-substituted imidazoles with aryl bromides have been devised. The first method, promoted by copper(I) iodide, is best suited for electron-poor aryl bromides, and also allows the 2,5-diarylation of thiazole and oxazole. The use of xylene instead of DMA is the key for the efficiency of the second method, which gives the best results with electron-rich aryl bromides.

    更新日期:2017-08-02
  • Short and Diastereoselective Total Synthesis of the Polyhydroxylated Pyrrolidine LAB-1: A Potent α-Glycosidase Inhibitor
    Synthesis (IF 2.650) Pub Date : 2017-07-27

    We described herein a total synthesis of 1,4-dideoxy-1,4-imino-l-arabinitol [(2S,3S,4S)-2-(hydroxymethyl)pyrrolidine-3,4-diol, LAB-1], a polyhydroxylated pyrrolidine, which has been demonstrated to be a selective and potent α-glycosidase inhibitor. The main features of our approach are its shortness, efficiency, and simplicity. The total synthesis was accomplished in 6 steps with an overall yield of 12%, starting from a chiral optically active Morita–Baylis–Hillman (MBH) adduct prepared (without epimerization), from Garner’s aldehyde. As far as we know, this is the first report describing the total synthesis of this biologically active pyrrolidine by exploring the synthetic versatility of a MBH adduct.

    更新日期:2017-07-28
  • meta- and para-Functionalized Thermally Crosslinkable OLED-Materials through Selective Transition-Metal-Catalyzed Cross-Coupling Reactions
    Synthesis (IF 2.650) Pub Date : 2017-07-26

    Herein, a synthetic approach using selective transition-metal-catalyzed cross-coupling reactions to thermally crosslinkable OLED materials­ based on vinyl-functionalized arylamines is reported. In a modular approach, 9,9-dialkyl-2,7-diiodo-9H-fluorene underwent a selective Ullmann cross-coupling reaction with bromo-substituted-diphenylamines to give 9,9-dialkyl-2,7-bis(bromo-substituted-diphenylamino)-9H-fluorenes that underwent end-functionalization by the Suzuki–Miyaura reaction using potassium vinyltrifluoroborate to give the corresponding 9,9-dialkyl-2,7-bis(vinyl-substituted-diphenylamino)-9H-fluorenes. Novel meta-functionalized materials were synthesized, which are difficult to prepare by traditional synthetic pathways. The thermal behavior of the compounds was investigated by DSC measurements, indicating a lower thermal sensitivity of the meta-substituted materials than their para-functionalized analogues.

    更新日期:2017-07-28
  • N-Heterocyclic Carbene-Catalyzed Activation of α-Chloroaldehydes: Asymmetric Synthesis of 5-Cyano-Substituted Dihydropyranones
    Synthesis (IF 2.650) Pub Date : 2017-07-26

    An N-heterocyclic carbene (NHC)-catalyzed asymmetric [4+2] annulation of (E)-2-benzoyl-3-phenylacrylonitriles with α-chloroaldehydes has been developed. The protocol leads to 5-cyano-substituted dihydropyranones in good to excellent yields with excellent diastereo- and enantioselectivities (up to 93% yield, >20:1 d.r. and 99% ee).

    更新日期:2017-07-28
  • Efficient One-Pot Synthesis of 2,4-Disubstituted Thiazoles and Dimeric Thiazoles Directly from Acyl Chlorides and β-Azido Disulfides
    Synthesis (IF 2.650) Pub Date : 2017-07-26

    A simple and effective one-pot cascade procedure to provide 2,4-disubstituted thiazoles and symmetrical dimeric thiazoles directly from commercially available acid chlorides and β-azido disulfides in moderate to high yields is described. This cascade transformation consists of disulfide cleavage, thiocarbonylation, phosphine-promoted intramolecular Staudinger/aza-Wittig reaction and dehydrogenation to form the corresponding thiazoles. The application of our methodology is demonstrated by the concise two-step synthesis of anticancer agent SMART and its O-linked dimer in 64% and 46% overall yields, respectively. This directed cascade reaction could be easily handled and scaled up under mild conditions, enabling the construction of focused thiazole derivatives for further pharmacological evaluation.

    更新日期:2017-07-28
  • Recent Advances in Reactions of Heteroatom-Centered Radicals
    Synthesis (IF 2.650) Pub Date : 2017-07-26

    Heteroatom-centered radicals show versatile reactivity and offer useful synthetic methods in organic chemistry. The development of new approaches for forming heteroatom-centered radicals has recently expanded the practicality of radical chemistry for synthesis. This review focuses on recent advances in reactions of representative heteroatom-centered radicals.

    更新日期:2017-07-28
  • Formation of Bicyclic Cyclopentenone Derivatives by Robinson-Type Annulation of Cyclic β-Oxoesters Containing a 1,4-Diketone Moiety
    Synthesis (IF 2.650) Pub Date : 2017-07-25

    Robinson-type cyclopentannulations of cyclic β-oxoesters possessing a 1,4-diketone moiety are accomplished under four different Brønsted basic reaction conditions. Using pyrrolidine/acetic acid in DMSO, an oxohexahydrocyclopenta[a]indene (42%) and an N-Boc-protected oxohexahydrocyclopenta[c]pyridine derivative (62%) are obtained with retention of the ester moieties. The latter compound defines an interesting new scaffold for medicinal chemistry with three positions allowing further derivatizations. The use of KOtBu in DMSO or NaH in toluene leads to cyclopentene derivatives with either partial ester saponification and decarboxylation or displacement of the ester moiety within the carbon skeleton. With aqueous KOH, the cyclopentannulations are successful in almost all cases, but with the ester moieties cleaved off. The respective bicyclic and tricyclic products are obtained in good to excellent yields. The 1,4-diketone starting materials are prepared by cerium-catalyzed oxidative coupling of β-oxoesters with isopropenyl acetate. Alternatively, a two-step sequence consisting of α-propargylation followed by palladium-catalyzed alkyne hydration is used.

    更新日期:2017-07-26
  • An Efficient Organic Electrosynthesis of β-Hydroxysulfones
    Synthesis (IF 2.650) Pub Date : 2017-07-25

    An efficient organic electrosynthesis of tertiary β-hydroxysulfones from functionalized α-methylstyrenes with substituted sodium sulfinates has been established. The novel electrosynthetic method provided the desired products in excellent yields, and the key structure was confirmed by X-ray single-crystal diffraction analysis.

    更新日期:2017-07-26
  • Facile Access to Amido (Thio)xanthates under Eco-Friendly Conditions by One-Pot Three-Component Reaction (3-CR)
    Synthesis (IF 2.650) Pub Date : 2017-07-25

    A straightforward three-component reaction (3-CR) for the preparation of a variety of biologically interesting amido (thio)xanthates has been developed. By the proper choice of a potassium (thio)xanthate salt, a cyclic or acyclic imine, and an acyl chloride as substrates a broad scope with respect to the substituents can be realized. This operationally simple one-pot method proceeds under mild and environmentally friendly conditions while potassium chloride is produced as the single waste-product.

    更新日期:2017-07-26
  • An Intramolecular Cycloaddition Approach to Construct Polysubstituted Pyrrolidones from Alkynyl Carboxamides and PTSA
    Synthesis (IF 2.650) Pub Date : 2017-07-25

    An efficient synthetic route to highly substituted pyrrolidone derivatives has been developed from an easily available alkynyl carboxamide and 4-methylbenzenesulfonic acid (PTSA). In the reaction, PTSA is not only used as acid catalyst but also as a reactant to provide a source for OTs group. A mechanism is proposed to involve the protonation of the alcohol substrate/cyclopropylcarbinol-homoallylic rearrangement/intramolecular N-nucleophilic cyclization reactions.

    更新日期:2017-07-26
Some contents have been Reproduced with permission of the American Chemical Society.
Some contents have been Reproduced by permission of The Royal Society of Chemistry.
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