bluuebunny/crossref_metadata_2025 huggingface dataset:
ChemInform Abstract: L‐Proline Catalyzed Efficient One‐Pot Three‐Component Aza‐Diels—Alder Reactions on Nitrostyrylisoxazoles: A Facile Synthesis of New Isoxazolyl Tetrahydroquinolines and Isoxazolo[2,3‐a]pyrimidines.
Authors: Rajanarendar E. , Reddy M. Nagi , Reddy K. Govardhan , Krishna S. Rama
Published: August 2012

Imines, generated in situ from aromatic aldehydes and amines, react with isoxazole substrates to give the trans‐cycloadducts with high diastereoselectivity (<80% d.e) in an enantiopure manner.
ChemInform Abstract: Microwave‐Assisted One‐Pot Synthesis of Benzothiazole and Benzoxazole Libraries as Analgesic Agents.
Authors: Praveen C. , Nandakumar A. , Dheenkumar P. , Muralidharan D. , Perumal P. T.
Published: August 2012

Libraries of the title compounds (III) and (V) are synthesized via iodosobenzene bis(trifluoroacetate) promoted cyclocondensation reactions.
ChemInform Abstract: Synthesis, Characterization and Evaluation of Antimicrobial Activity of Some Novel 1,2,4‐Triazoles and 1,3,4‐Thiadiazoles Bearing Imidazole Nucleus.
Authors: Aouad Mohamed Reda , Rezki Nadjet , Kasmi Mohamed , Aouad Linda , Rezki Merieme A.
Published: August 2012

The antimicrobial activity data of the new compounds reveal that derivatives bearing a triazole moiety exhibit better antibacterial activity compared to the thiadiazole substituent.
ChemInform Abstract: Facile Synthesis, Characterization and Pharmacological Activities of 3,6‐Disubstituted 1,2,4‐Triazolo[3,4‐b][1,3,4]thiadiazoles and 5,6‐Dihydro‐3,6‐disubstituted‐1,2,4‐triazolo[3,4‐b][1,3,4]thiadiazoles.
Authors: Chidananda N. , Poojary Boja , Sumangala V. , Kumari N. Suchetha , Shetty Prashanth , Arulmoli T.
Published: August 2012

Two new series of compounds, triazolothiadiazoles (V) and (VIII) are synthesized by cyclocondensation of dihydrotriazolethione (III) with aromatic carboxylic acids (IV) and by reaction of (III) with aromatic aldehydes (VI) yielding the open chain hydrazones (VII) which undergo intramolecular Mannich reaction in the presence of toluenesulfonic acid.
ChemInform Abstract: Copper(I)‐Catalyzed Hydroalkoxylation/Hydrogen‐Bonding‐Induced Asymmetric Hetero‐Diels—Alder Cycloaddition Cascade: An Approach to Aromatic Spiroketals.
Authors: Li Xin , Xue Jijun , Huang Chusheng , Li Ying
Published: August 2012

Under optimized conditions, o‐(hydroxypropynyl)phenols (I) react with o‐(acetoxymethyl)phenols (II) to give spiro[benzofuran‐2,2′‐benzopyran] derivatives (III) with <20:1 diastereoselectivity in all cases for the cis‐isomers.
ChemInform Abstract: Xanthan Sulfuric Acid: An Efficient and Recyclable Solid Acid Catalyst for Pechmann Condensation.
Authors: Kuarm B. Suresh , Madhav J. Venu , Rajitha B.
Published: August 2012

The reaction is conducted under solvent‐free conditions.
ChemInform Abstract: Palladium‐Catalyzed Oxidative Double C—H Functionalization/Carbonylation for the Synthesis of Xanthones.
Authors: Zhang Hua , Shi Renyi , Gan Pei , Liu Chao , Ding Anxing , Wang Qiuyi , Lei Aiwen
Published: August 2012

Xanthones with different functional groups (III) are obtained by reaction of diarylethers (I) with carbon monoxide in the presence of a simple catalytic system consisting of Pd(OAc)2, K2S2O8, and trifluoroacetic acid.
ChemInform Abstract: Molecular Scaffolds with Remote Directing Groups for Selective Palladium‐Catalyzed C—H Bond Functionalizations.
Authors: Stache Erin E. , Seizert Curtis A. , Ferreira Eric M.
Published: August 2012

In aminals such as (III) derived from L‐proline, a proximal relationship is established by the bicyclic moiety with syn‐orientation between the pyridyl directing group and the aromatic or aliphatic group originating from the aldehyde.
ChemInform Abstract: Direct Oxidative Arylation via Rhodium‐Catalyzed C—C Bond Cleavage of Secondary Alcohols with Arylsilanes.
Authors: Chen Kang , Li Hu , Li Yang , Zhang Xi‐Sha , Lei Zhi‐Quan , Shi Zhang‐Jie
Published: August 2012

Under optimized conditions using AgF as oxidant, 1,1‐biarylmethanols bearing a pyridyl directing group undergo a Rh(III)‐catalyzed C—C cleavage and subsequent coupling with arylsilanes to give (biphenyl)pyridine derivatives.
ChemInform Abstract: New Synthesis of Pyrvinium that Inhibits the β‐Catenin/TCF4 Pathway.
Authors: Mao Yongjun , Lin Nan , Tian Wang , Huang Ziwei , An Jing
Published: August 2012

The method uses easily available materials and simple reactions, including the key Friedlaender condensation, to assemble the quinoline ring.
ChemInform Abstract: A Catalytic Multicomponent Approach for the Stereoselective Synthesis of cis‐4,5‐Disubstituted Pyrrolidinones and Tetrahydro‐3H‐pyrrolo[3,2‐c]quinolines.
Authors: Roy Sudipta , Reiser Oliver
Published: August 2012

The reaction of a furancarbaldehyde, an aniline, and cyclopropanated pyrrole (I) affords cis‐5‐furyl‐4‐quinolyl‐substituted pyrrolidinones with excellent stereoselectivity.
ChemInform Abstract: Conventional and Microwave‐Assisted Synthesis of Pyrazole Derivatives and Screening of Their Antibacterial and Antifungal Activities.
Authors: Mistry B. D. , Desai K. R. , Patel J. A. , Patel N. I.
Published: August 2012

Three series of novel quinolylpyrazole derivatives (IV), (VI) and (VIII) are synthesized by condensation reactions of propenone derivatives (III) with hydrazine or semicarbazide derivatives under conventional heating or microwave irradiation conditions.
ChemInform Abstract: Two‐, Three‐ and Four‐Component Coupling to Form Isoquinolones Based on Directed Metalation.
Authors: Antczak Monika I. , Ready Joseph M.
Published: August 2012

Benzamides undergo ortho‐metalation with magnesiate bases to allow trapping with propargylic chlorides.
ChemInform Abstract: Isoquinoline Derivatives as Potent CRTH2 Receptor Antagonists: Synthesis and SAR.
Authors: Nishikawa‐Shimono Rie , Sekiguchi Yoshinori , Koami Takeshi , Kawamura Madoka , Wakasugi Daisuke , Watanabe Kazuhito , Wakahara Shunichi , Matsumoto Kayo , Takayama Tetsuo
Published: August 2012

The most potent compound, TASP0376377 (I) shows good CRTH2 antagonist potency, as well as sufficient selectivity for binding to CRTH2 over the DP1 prostanoid receptor and COX‐1 and COX‐2 enzymes.
ChemInform Abstract: Ultrasound‐Promoted One‐Pot Three‐Component Synthesis of Novel 7‐Aryl‐8H‐benzo[h]indeno[1,2‐b]quinolin‐8‐ones under Solvent‐Free Conditions.
Authors: Mamaghani Manouchehr , Larghani Tahere Hosseyni
Published: August 2012

10 Title compounds of type (IV) are prepared by a one‐pot three‐component reaction using ultrasound irradiation.
ChemInform Abstract: Skraup‐Like Cyclization of Polyfluoro‐2‐naphthylamines: Vicarious Electrophilic Substitution of Fluorine.
Authors: Selivanova Galina A. , Reshetov Alexey V. , Bagryanskaya Irina Yu , Shteingarts Vitalij D.
Published: August 2012

This rare fluorine substitution process putatively proceeds via the mechanism of vicarious electrophilic substitution.
ChemInform Abstract: A Novel Pathway to Imidazo[1,2‐a]pyridines. Access Through Imino Pyridinium Salts.
Authors: Neue Benedikt , Froehlich Roland , Wuerthwein Ernst‐Ulrich
Published: August 2012

The electrocyclization reaction of imino pyridinium salts (III) yields imidazopyridines (IV) or (V).
ChemInform Abstract: Thienopyridine Ureas as Dual Inhibitors of the VEGF and Aurora Kinase Families.
Authors: Curtin Michael L. , et al. et al.
Published: August 2012

New thienopyridine ureas (I) are potent inhibitors against the Aurora kinases that are efficacious in mouse tumor models after oral dosing.
ChemInform Abstract: New Efficient Synthesis of 5,6‐Disubstituted‐3‐phenyl‐1,2,3‐triazolo[4,5‐d]pyrimidin‐7‐ones via a Tandem Aza‐Wittig Reaction.
Authors: Wang Tao , Ke Xi Xian , Zhou Shui Tao , Chen Hui Zong
Published: August 2012

Most of the title compounds (VI) (12 examples) possess good herbicidal activity against the roots and stalk of rape and barnyard grass.
ChemInform Abstract: First Representative of 6b,9‐Epoxyisoindolo[2,1‐a]quinazoline‐10‐carboxylic Acids.
Authors: Zaytsev V. P. , Zubkov F. I. , Motorygina E. L. , Gorbacheva M. G. , Nikitina E. V. , Varlamov A. V.
Published: August 2012

Acylation of quinazolinones (IV) with maleic anhydride in refluxing toluene is accompanied by a spontaneous exo‐[4 + 2] cycloaddition to furnish the title compounds (IV) as single diastereomers.
ChemInform Abstract: Cytotoxicity and anti‐HIV Evaluations of Some New Synthesized Quinazoline and Thioxopyrimidine Derivatives Using 4‐(Thiophen‐2‐yl)‐3,4,5,6‐tetrahydrobenzo[h]quinazoline‐2(1H)‐thione as Synthon.
Authors: Mohamed Yahia A. , Amr Abd El‐Galil E. , Mohamed Salwa F. , Abdalla Mohamed M. , Al‐Omar Mohamed A. , Shfik Samira H.
Published: August 2012

A series of dihydrobenzo[h]quinazoline derivatives is synthesized starting from compounds (I), (IX) or (XVII).
ChemInform Abstract: Design and Optimization of Quinazoline Derivatives as Melanin Concentrating Hormone Receptor 1 (MCHR1) Antagonists. Part 2.
Authors: Sasmal Pradip K. , et al. et al.
Published: August 2012

Detailed SAR studies result in the identification of a lead optimized candidate (Ia).
ChemInform Abstract: Synthesis and Antibacterial Evaluation of Benzazoles Tethered Dihydro[1,3]oxazines.
Authors: Prasad Davinder , Rohilla Rajesh Kumar , Roy Nilanjan , Nath Mahendra
Published: August 2012

A variety of novel benzazoles tethered oxazines are synthesized via three‐component one‐pot Mannich type condensation—cyclization reactions of substituted phenols or β‐naphthol with formaldehyde and benzazolylphenylamines.
ChemInform Abstract: A Novel and Highly Efficient Protocol for the Synthesis of Chalcone Based 1,2‐Diazepine and 1,2‐Oxazepine Derivatives.
Authors: Babu B. Venkata , Ahmed Naseem
Published: August 2012

The mixing and grinding of 1,5‐diketones (III) with hydrazine affords the title compounds (IV) in high yields within 10 ‐ 20 min.
ChemInform Abstract: Unprecedented Temperature‐Dependent Formation of 3‐ and 7‐Methyl‐3H‐azepine Derivatives by the Reaction of o‐Nitrotoluene with Tributylphosphine in Nucleophilic Media.
Authors: Ulfa Siti Mariyah , Okamoto Hideki , Satake Kyosuke
Published: August 2012

The reaction of o‐methylphenylnitrene in the presence of alcohol (II) and amine (V) is expected to give isomeric pairs of 3‐and 7‐methyl‐3H‐azepine derivatives (III)/(IV) and (VI)/(VII).
ChemInform Abstract: Medium‐Sized Rings versus Macrocycles Through Rhodium‐Catalyzed Ring‐Expansion Reactions of Cyclic Acetals.
Authors: Ballesteros‐Garrido Rafael , Rix Diane , Besnard Celine , Lacour Jerome
Published: August 2012

Unprecedented polyoxygenated 8‐ and 9‐membered rings are synthesized in one pot by reaction of various α‐diazo β‐ketoesters and diketones with cyclic acetals.
ChemInform Abstract: Copper‐Catalyzed Double Borylation of Silylacetylenes: Highly Regio‐ and Stereoselective Synthesis of syn‐Vicinal Diboronates.
Authors: Jung Ho‐Young , Yun Jaesook
Published: August 2012

In the presence of copper catalyst, silylacetylene and aryl‐substituted alkynylsilanes undergo regio‐ and stereoselective bis‐borylation to afford products of type (III)/(V).
ChemInform Abstract: Ruthenium‐Catalyzed Orthoselective Aromatic C—H Silylation: Acceptorless Dehydrogenative Coupling of Hydrosilanes.
Authors: Sakurai Toru , Matsuoka Yusuke , Hanataka Tsurugi , Fukuyama Naoaki , Namikoshi Takeshi , Watanabe Shinji , Murata Miki
Published: August 2012

The intermolecular dehydrogenative coupling of trisiloxane (II) with aromatic compounds such as arylimines (I) and aryloxazolines (VI) in the presence of a Ru‐catalyst affords the corresponding ortho‐silylated products in good yields.
ChemInform Abstract: Hybrid Metal/Organo Relay Catalysis Enables Enynes To Be Latent Dienes for Asymmetric Diels—Alder Reaction.
Authors: Han Zhi‐Yong , Chen Dian‐Feng , Wang Ya‐Yi , Guo Rui , Wang Pu‐Sheng , Wang Chao , Gong Liu‐Zhu
Published: August 2012

Gold complex BPG in combination with chiral Broensted acid PHA catalyzes the title reaction of enynyl silanols with either naphthoquinone or quinones to give penta‐ and tetracyclic oxasiline derivatives, correspondingly, as single diastereomers and with excellent enantioselectivities.
ChemInform Abstract: Synthesis and Antitumor Activity of 3‐[(Methyl)bis(5‐trialkylsilylfuran‐2‐yl)silyl]propylamines.
Authors: Ignatovich L. , Romanov V. , Spura J. , Propelis J. , Domracheva I. , Shestakova I.
Published: August 2012

The title compounds (V) (8 examples) are obtained by hydrosilylation of aliphatic and heterocyclic N‐alkylamines in the presence of Speier′s catalyst.
ChemInform Abstract: Rhodium‐Catalyzed Intramolecular trans‐Bis‐silylation of Alkynes to Synthesize 3‐Silyl‐1‐benzosiloles.
Authors: Matsuda Takanori , Ichioka Yoichiro
Published: August 2012

This is the first example of the title reaction.
ChemInform Abstract: Base‐Catalyzed Direct Aldolization of α‐Alkyl‐α‐hydroxy Trialkyl Phosphonoacetates.
Authors: Corbett Michael T. , Uraguchi Daisuke , Ooi Takashi , Johnson Jeffrey S.
Published: August 2012

The direct addition of the title phosphonoacetates to aldehydes is based on the in situ generation of reactive glycolate enolate intermediates by a [1,2] phosphonate—phosphate rearrangement to give α‐hydroxy β‐phosphonyloxy esters with modest diastereoselectivities.
ChemInform Abstract: Synthesis of Cyclotriphosphazenes Containing Cyanostilbenes with Different Terminal Substituents.
Authors: Bao Rui , Pan Min , Zhou Yun , Qiu Jin‐Jun , Tang He‐Qing , Liu Cheng‐Mei
Published: August 2012

Cyclotriphosphazenes (IVa) and (IVb) with terminal substituents exhibit nematic phases.
ChemInform Abstract: Superbase‐Assisted Addition of Phosphine to 1‐Methoxy‐4‐vinylbenzene: Toward a Rare Family of Organic Phosphines.
Authors: Malysheva S. F. , Gusarova N. K. , Artem'ev A. V. , Belogorlova N. A. , Smirnov V. I. , Shagun V. A. , Kuimov V. A. , Trofimov B. A.
Published: August 2012

Gaseous phosphine reacts with p‐methoxystyrene at 70°C to afford bis(methoxyphenylethyl)phosphine (II) in high yield.
ChemInform Abstract: Stereocontrolled 1,3‐Phosphatyloxy and 1,3‐Halogen Migration Relay Toward Highly Functionalized 1,3‐Dienes.
Authors: Shiroodi Roohollah Kazem , Dudnik Alexander S. , Gevorgyan Vladimir
Published: August 2012

The first example of 1,3‐migration of iodine is presented, cf.
ChemInform Abstract: Synthesis of 3‐Fluoro‐2‐(diethoxyphosphoryl)imidazo[1,2‐a]pyridine.
Authors: Aksinenko Alexei Yu. , Goreva Tatyana V. , Epishina Tatyana A. , Sokolov Vladimir B.
Published: August 2012

The Arbuzov and defluorocyclization reaction are combined for the synthesis of the first representative of 3‐fluoro‐2‐(dialkoxyphosphoryl)imidazopyridines (V).
ChemInform Abstract: A Zinc Porphyrin‐Based Molecular Probe for the Determination of Contamination in Commercial Acetonitrile.
Authors: Yoon Hongsik , Lee Chi‐Hwa , Jeong Young‐Hwan , Gee Hyuk‐Chan , Jang Woo‐Dong
Published: August 2012

By means of charting the absorption spectrum in MeCN, the cyanide contamination concentration can be directly determined.
ChemInform Abstract: Azobenzenes in a New Light—Switching in vivo.
Authors: Wegner Hermann A.
Published: August 2012

The title compounds represent attractive tools for the control of biological functions in vivo by light.
ChemInform Abstract: Olean‐18‐ene Triterpenoids from Celastraceae Species Inhibit HIV Replication Targeting NF‐kB and Sp1 Dependent Transcription.
Authors: Osorio Alex A. , Munoz Alejandro , Torres‐Romero David , Bedoya Luis M. , Perestelo Nayra R. , Jimenez Ignacio A. , Alcami Jose , Bazzocchi Isabel L.
Published: August 2012

Among nine new oleanene triterpenes, isolated from the stems of C.
ChemInform Abstract: Nonnatural Amino Acid Synthesis by Using Carbon—Hydrogen Bond Functionalization Methodology.
Authors: Tran Ly Dieu , Daugulis Olafs
Published: August 2012

Syntheses of substituted phenylalanine derivatives (III) are highly convergent and employ an N‐phthaloylalanine with a 2‐thiomethylaniline directing group.
ChemInform Abstract: Pyronepolyene C‐Glucosides with NF‐ϰB Inhibitory and anti‐Influenza A Viral (H1N1) Activities from the Sponge‐Associated Fungus Epicoccum sp. JJY40.
Authors: Peng Jixing , Jiao Jieying , Li Jing , Wang Wei , Gu Qianqun , Zhu Tianjiao , Li Dehai
Published: August 2012

A new pyronepolyene C‐glucoside, iso‐D8646‐2‐6 (I), is isolated together with the known related compound D8646‐2‐6.
ChemInform Abstract: Acremolin, a New 1H‐Azirine Metabolite from the Marine‐Derived Fungus Acremonium strictum.
Authors: Julianti Elin , Oh Hana , Lee Hyi‐Seung , Oh Dong‐Chan , Oh Ki‐Bong , Shin Jongheon
Published: August 2012

The component is inactive against Gram‐positive and Gram‐negative bacteria, but exhibits weak cytotoxicity against an A54 cell line.
ChemInform Abstract: Alternative Mild Route to the Synthesis of 4‐Methylenecyclohex‐2‐enone, a Key Moiety of the Anticancer Compounds Ottelione A and B.
Authors: Lestini Elena , Robertson Keith , Murphy Cormac D. , Paradisi Francesca
Published: August 2012

Key feature of this synthesis is the iodide‐induced formation of the highly conjugated ketone (V) from mesylate (IVa).
ChemInform Abstract: Cytotoxic Cytochalasins from the Endozoic Fungus Phoma sp. of the Giant Jellyfish Nemopilema nomurai.
Authors: Jung Jee H. , et al. et al.
Published: August 2012

Cytochalasin B2 (I), deoxaphomin B (II), deoxaphomin C (III) and 20‐deoxycytochalasin F (IV) are isolated together with known cytochalasin B.
ChemInform Abstract: Atom Tunneling in Organic Transformations.
Authors: Patureau Frederic W.
Published: August 2012

A short list of illustrative examples of hydrogen and deuterium atom tunneling is highlighted.
ChemInform Abstract: Design, Synthesis and Biological Evaluation of Thiazole‐ and Indole‐Based Derivatives for the Treatment of Type II Diabetes.
Authors: Chen Lijuan , et al. et al.
Published: August 2012

Thirty eight thiazole‐ and indole‐based derivatives are prepared and examined for their inhibitory effects on the production of LPS‐induced TNF‐α.
ChemInform Abstract: Progresses in the Pursuit of Aldose Reductase Inhibitors: The Structure‐Based Lead Optimization Step.
Authors: Marinelli Luciana , et al. et al.
Published: August 2012

Starting from the virtual screening‐derived aldose reductase2 inhibitor S12728, a rational receptor‐based lead optimization results in the discovery of compounds (I) endowed with low micromolar/submicromolar activities.
ChemInform Abstract: Novel Pyrrolopyrimidine Analogues as Potent Dipeptidyl Peptidase IV Inhibitors Based on Pharmacokinetic Property‐Driven Optimization.
Authors: Hu Wenhui , et al. et al.
Published: August 2012

Replacement of the thienopyrimidine scaffold of recently reported dipeptidyl peptidase IV inhibitors with a pyrrolopyrimidine system improves the metabolic stability of the remaining parent in model liver microsomes, while resulting in poor absorption.
ChemInform Abstract: Research Highlights from the U.S. Department of Energy′s Working Group on Photoelectrochemical Hydrogen Production
Authors: Miller Eric L. , Garland Roxanne , Dillich Sara
Published: August 2012

Review: 43 refs.
ChemInform Abstract: Materials for Proton Conducting Solid Oxide Fuel Cells (H‐SOFCs)
Authors: Thangadurai V. , Kan W. H. , Mirfakhraei B. , Bhella S. S. , Trinh T. T.
Published: August 2012

Review: 28 refs.
ChemInform Abstract: Individual Nanostructured Materials: Fabrication and Surface‐Enhanced Raman Scattering
Authors: Gong Xiao , Bao Ying , Qiu Chao , Jiang Chaoyang
Published: August 2012

Review: 145 refs.
ChemInform Abstract: Nanorings
Authors: Krishna Katla Sai , Eswaramoorthy Muthusamy
Published: August 2012

Review: 61 refs.
ChemInform Abstract: One‐dimensional Metal Oxide Nanostructures
Authors: Varghese Binni , Sow Chorng Haur , Lim Chwee Teck
Published: August 2012

Review: 228 refs.
ChemInform Abstract: From Silicon to Carbon Clathrates: Nanocage Materials
Authors: Melinon Patrice , San Miguel Alfonso
Published: August 2012

Review: 113 refs.
ChemInform Abstract: Multiple Superconducting Gaps, Anisotropic Spin Fluctuations and Spin—Orbit Couplings in Iron Pnictides
Authors: Yang Jie , Zheng Guo‐Qing
Published: August 2012

Review: 56 refs.
ChemInform Abstract: Multiferroic Materials
Authors: Achary S. N. , Jayakumar O. D. , Tyagi A. K.
Published: August 2012

Review: 193 refs.
ChemInform Abstract: Ferromagnetic Lanthanum Manganites
Authors: Bebenin N. G.
Published: August 2012

Review: 38 refs.
ChemInform Abstract: Magnetism in Metal Oxide Nanostructures
Authors: Yi Jiabao , Ding Jun , Feng Yuanping
Published: August 2012

Review: 438 refs.
ChemInform Abstract: Magnetic Metal Oxide Nanocrystals and Their Applications
Authors: Trudel Simon , Hill Ross H.
Published: August 2012

Review: 476 refs.
ChemInform Abstract: Transition Metal Ferrite Nanocrystals: Synthesis, Properties and Applications
Authors: Caruntu Daniela , Ganju Dumitru , Caruntu Gabriel , O'Connor Charles J.
Published: August 2012

Review: 260 refs.
ChemInform Abstract: Synthesis and Reactivity of 2‐Azametallacyclobutanes
Authors: Dauth Alexander , Love Jennifer A.
Published: August 2012

Review: 74 refs.
ChemInform Abstract: Enantiomeric Natural Products: Occurrence and Biogenesis
Authors: Finefield Jennifer M. , Sherman David H. , Kreitman Martin , Williams Robert M.
Published: August 2012

Review: alkaloids, terpenes, phenylpropanoids, polyketides; 326 refs.
ChemInform Abstract: Recognition and Sensing of Various Species Using Boronic Acid Derivatives
Authors: Guo Zhiqian , Shin Injae , Yoon Juyoung
Published: August 2012

Review: 65 refs.
ChemInform Abstract: Organic Foldamers and Helices
Authors: Huc Ivan , Jiang Hua
Published: August 2012

Review: 66 refs.
ChemInform Abstract: Self‐Assembly of Organic Supramolecular Capsules
Authors: Scarso Alessandro , Borsato Giuseppe
Published: August 2012

Review: 126 refs.
ChemInform Abstract: Dimethylamino Amination with DMF
Authors: Agarwal Anu , Chauhan Prem M. S.
Published: August 2012

Review: 25 refs.
ChemInform Abstract: Engineering Cyclic Peptide Toxins
Authors: Clark Richard J. , Craik David J.
Published: August 2012

Review: 47 refs.
ChemInform Abstract: From EPOthilone to EPO: A Challenge for Natural Product Synthesis
Authors: Brown Zachary Z. , Muir Tom W.
Published: August 2012

Review: 15 refs.
ChemInform Abstract: 2,5‐Diketopiperazines: Synthesis, Reactions, Medicinal Chemistry, and Bioactive Natural Products
Authors: Borthwick Alan D.
Published: August 2012

Review: 604 refs.
ChemInform Abstract: Recent Developments in Oxidative Processes in Steroid Chemistry
Authors: Salvador Jorge A. R. , Silvestre Samuel M. , Moreira Vania M.
Published: August 2012

Review: 190 refs.
ChemInform Abstract: Cationic Tricoordinate Boron Intermediates: Borenium Chemistry from the Organic Perspective
Authors: De Vries Timothy S. , Prokofjevs Aleksandrs , Vedejs Edwin
Published: August 2012

Review: 179 refs.
ChemInform Abstract: Preparation and Chemistry of 3/5‐Halogenopyrazoles
Authors: Janin Yves L.
Published: August 2012

Review: 489 refs.
ChemInform Abstract: Focused Update on the Prins Reaction and the Prins Cyclization
Authors: Pastor Isidro M. , Yus Miguel
Published: August 2012

Review: 202 refs.
ChemInform Abstract: Iodocyclization, Followed by Palladium‐Catalyzed Coupling. A Versatile Strategy for Heterocyclic Library Construction
Authors: Dubrovskiy Anton V. , Markina Nataliya A. , Larock Richard C.
Published: August 2012

Review: 83 refs.
ChemInform Abstract: Synthesis of Celecoxib and Structural Analogs
Authors: Dadiboyena Sureshbabu , Hamme Ashton T. II
Published: August 2012

Review: 108 refs.
ChemInform Abstract: Recent Advances in the Medicinal Chemistry of Aurones
Authors: Haudecoeur R. , Boumendjel A.
Published: August 2012

Review: 122 refs.
ChemInform Abstract: Fumagillin and Structurally Related Molecules as Source of New Drugs
Authors: Gamba‐Sanchez Diego
Published: August 2012

Review: 80 refs.
ChemInform Abstract: Xanthones from Fungi, Lichens, and Bacteria: The Natural Products and Their Synthesis
Authors: Masters Kye‐Simeon , Braese Stefan
Published: August 2012

Review: 481 refs.
ChemInform Abstract: Transition Metal Salt‐Mediated Radical Reactions of [60]Fullerene
Authors: Wang Guan‐Wu , Li Fa‐Bao
Published: August 2012

Review: 31 refs.
ChemInform Abstract: Synthesis and Structure of Halogenated Fullerenes
Authors: Troyanov Sergey I. , Kemnitz Erhard
Published: August 2012

Review: 142 refs.
ChemInform Abstract: Reaction Mechanisms: Stripping Down SN2
Authors: Orr‐Ewing Andrew J.
Published: August 2012

Review: 7 refs.
ChemInform Abstract: Rhodium‐Catalyzed C—C Bond Cleavage Reactions
Authors: Korotvicka Ales , Necas David , Kotora Martin
Published: August 2012

Review: 211 refs.
ChemInform Abstract: Designer‐Surfactant‐Enabled Cross‐Couplings in Water at Room Temperature
Authors: Lipshutz Bruce H. , Ghorai Subir
Published: August 2012

Review: 141 refs.
ChemInform Abstract: Recent Advances in Iridium‐Catalyzed Asymmetric Hydrogenation: New Catalysts, Substrates and Applications in Total Synthesis
Authors: Ganic Adnan , Rageot Denise , Trondlin Lars , Pfaltz Andreas
Published: August 2012

Review: 67 refs.
ChemInform Abstract: The Utilization of Rice Husk Silica as a Catalyst: Review and Recent Progress
Authors: Adam Farook , Appaturi Jimmy Nelson , Iqbal Anwar
Published: August 2012

Review: 65 refs.
ChemInform Abstract: Rational Design and Synthesis of Potent Myelin Cyclic Peptide Analogues with Enhanced Stability and Biological Properties
Authors: Tselios Theodore V. , Matsoukas John M.
Published: August 2012

Review: 26 refs.
ChemInform Abstract: Medicinal Chemistry Applied to the Protein Molecule — Total Protein Synthesis by Native Chemical Ligation of Synthetic Peptides
Authors: Soma Yohei , Kent Stephen B. H.
Published: August 2012

Review: 14 refs.
ChemInform Abstract: The CH/π Hydrogen Bond: Implication in Chemistry
Authors: Nishio M.
Published: August 2012

Review: 85 refs.
ChemInform Abstract: Spin‐Center Shift Reactions
Authors: Wessig Pablo
Published: August 2012

Review: 78 refs.
ChemInform Abstract: Synthesis and Immunomodulatory Activities of Helicobacter Pylori Lipophilic Terminus of Lipopolysaccharide Including Lipid A
Authors: Fujimoto Yukari , Shimoyama Atsushi , Suda Yasuo , Fukase Koichi
Published: August 2012

Review: 40 refs.
ChemInform Abstract: Modern Methods of Thermochemical Biomass Conversion into Gas, Liquid and Solid Fuels
Authors: Lewandowski Witold M. , Radziemska Ewa , Ryms Michal , Ostrowski Piotr
Published: August 2012

Review: 23 refs.
ChemInform Abstract: Liquid—Crystalline Phthalocyanine‐Based Nanostructures
Authors: Tsivadze A. Yu. , Nosikova L. A. , Kudryashova Z. A.
Published: August 2012

Review: 154 refs.
ChemInform Abstract: Organic—Inorganic Nanocomposite Polymer Electrolyte Membranes for Fuel Cells: Recent Developments
Authors: Tripathi Bijay P. , Shahi Vinod K.
Published: August 2012

Review: 253 refs.
ChemInform Abstract: The Technology of Curatives Used with Epoxy Resins for Composite Applications
Authors: McCarvill William T.
Published: August 2012

Review: 86 refs.
ChemInform Abstract: Hydrotalcites in Nanobiocomposites
Authors: Costantino U. , Nocchetti M. , Gorrasi G. , Tammaro L.
Published: August 2012

Review: 161 refs.
ChemInform Abstract: Chemical Production from Lignocellulosic Biomass: Thermochemical, Sugar and Carboxylate Platforms
Authors: Smith A. D. , Landoll M. , Falls M. , Holtzapple M. T.
Published: August 2012

Review: 52 refs.
ChemInform Abstract: Vibrational Spectroscopy of Mono‐ and Polynuclear Spin‐Crossover Systems
Authors: Wolny Juliusz A. , Diller Rolf , Schuenemann Volker
Published: August 2012

Review: [i.e.
ChemInform Abstract: Fluorescence Response of Alkaloids and DAPI on Inclusion in Cucurbit[7]uril: Utilization for the Study of the Encapsulation of Ionic Liquid Cations
Authors: Biczok Laszlo , Wintgens Veronique , Miskolczy Zsombor , Megyesi Monika
Published: August 2012

Review: 74 refs.
Gaussian Free Field in an Interlacing Particle System with Two Jump Rates
Authors: Duits Maurice
Published: August 2012

We study the fluctuations of a random surface in a stochastic growth model on a system of interlacing particles placed on a two‐dimensional lattice. There are two different types of particles, one with a low jump rate and the other with a high jump rate. In the large time limit, the random surface has a deterministic shape. Due to the different jump rates, the limit shape and the domain on which it is defined are not smooth. The main result is that the fluctuations of the random surface are governed by the Gaussian free field. © 2012 Wiley Periodicals, Inc.
Hydrothermal Reaction Kinetics and Pathways of Phenylalanine Alone and in Binary Mixtures
Authors: Changi Shujauddin , Zhu Minghan , Savage Phillip E.
Published: August 2012

We examined the behavior of phenylalanine in high‐temperature water (HTW) at 220, 250, 280, and 350 °C. Under these conditions, the major product is phenylethylamine. The minor products include styrene and phenylethanol (1‐phenylethanol and 2‐phenylethanol), which appear at higher temperatures and longer batch holding times. Phenylethylamine forms via decarboxylation of phenylalanine, styrene forms via deamination of phenylethylamine, and phenylethanol forms via hydration of styrene. We quantified the molar yields of each product at the four temperatures, and the carbon recovery was between 80–100 % for most cases. Phenylalanine disappearance follows first‐order kinetics with an activation energy of 144±14 kJ mol−1 and a pre‐exponential factor of 1012.4±1.4 min−1. A kinetics model based on the proposed pathways was consistent with the experimental data. Effects of five different salts (NaCl, NaNO3, Na2SO4, KCl, K2HPO4) and boric acid (H3BO3) on phenylalanine behavior at 250 °C have also been elucidated. These additives increase phenylalanine conversion, but decrease the yield of phenylethylamine presumably by promoting formation of high molecular weight compounds. Lastly, binary mixtures of phenylalanine and ethyl oleate have been studied at 350 °C and three different molar concentration ratios. The presence of phenylalanine enhances the conversion of ethyl oleate and molar yields of fatty acid. Higher concentration of ethyl oleate leads to increased deamination of phenylethylamine and hydration of styrene. Amides are also formed due to the interaction of oleic acid/ethyl oleate and phenylethylamine/ammonia and lead to a decrease in the fatty acid yields. Taken collectively, these results provide new insights into the reactions of algae during its hydrothermal liquefaction to produce crude bio‐oil.
The Synthesis and the Chemical and Physical Properties of Non‐Aqueous Silylamine Solvents for Carbon Dioxide Capture
Authors: Rohan Amy L. , Switzer Jackson R. , Flack Kyle M. , Hart Ryan J. , Sivaswamy Swetha , Biddinger Elizabeth J. , Talreja Manish , Verma Manjusha , Faltermeier Sean , Nielsen Paul T. , Pollet Pamela , Schuette George F. , Eckert Charles A. , Liotta Charles L.
Published: August 2012

Silylamine reversible ionic liquids were designed to achieve specific physical properties in order to address effective CO2 capture. The reversible ionic liquid systems reported herein represent a class of switchable solvents where a relatively non‐polar silylamine (molecular liquid) is reversibly transformed to a reversible ionic liquid (RevIL) by reaction with CO2 (chemisorption). The RevILs can further capture additional CO2 through physical absorption (physisorption). The effects of changes in structure on (1) the CO2 capture capacity (chemisorption and physisorption), (2) the viscosity of the solvent systems at partial and total conversion to the ionic liquid state, (3) the energy required for reversing the CO2 capture process, and (4) the ability to recycle the solvents systems are reported.
Identification and characterization of 2,5‐dimethoxy‐3,4‐dimethyl‐β‐phenethylamine (2C‐G) – A new designer drug
Authors: Zuba Dariusz , Sekuła Karolina
Published: August 2012

This study presents and discusses the mass spectrometric, infrared spectroscopic and nuclear magnetic resonance spectroscopic data of 2,5‐dimethoxy‐3,4‐dimethyl‐β‐phenethylamine (2C‐G), a new designer drug. A powder sample containing 2C‐G was seized in Poland in 2011. The paper focuses on a comparison of the analytical features of 2C‐G and other members of the 2C‐series, in order to assess the possibility of unequivocal identification. The occurrence of intense peak at m/z = 178 and different intensities of the ions at m/z = 165 and 180 in the gas chromatography‐electron impact‐mass spectrometry (GC‐EI/MS) spectrum of 2C‐G made it possible to distinguish it from 2C‐E. Differences in relative intensities of the ions at m/z = 192, 179 and 177 were observed for GC‐EI/MS spectra of TFAA derivatives of 2C‐G and 2C‐E. An identical set of ions was recorded for these substances using the liquid chromatography‐electrospray ionization/quadrupole time of flight mass spectrometry (LC‐ESI/QTOFMS) method in both MS and tandem mass spectrometry (MS/MS) mode, but the distinction was possible based on differences in the ion intensities at m/z = 193.1223 and 178.0988. The Fourier transform infrared (FTIR) spectrum of 2C‐G was significantly different from other members of the 2C‐series, with a characteristic doublets at 993–1014 cm‐1 and 1099–1124 cm‐1, and the ratio of bands at higher wavenumbers. Final elucidation of the structure of 2C‐G was carried out by 1H and 13C NMR spectroscopy.

The study indicated that the marketing of analogues of controlled substances poses a real analytical challenge for forensic laboratories, and the application of sophisticated methods is often required for unequivocal identification of a new substance. Copyright © 2012 John Wiley & Sons, Ltd.
Influence of contrasting riparian forest cover on stream temperature dynamics in salmonid spawning and nursery streams
Authors: Imholt C. , Soulsby C. , Malcolm I.A. , Gibbins C.N.
Published: August 2012

In this paper, we investigated the influence of contrasting riparian forest types on upland stream temperatures and the links between thermal regime and standard indices of forest cover. Stream temperature was measured for two hydrological years at multiple sites along two tributaries of the River Dee, Scotland. Riparian cover in the upper reaches of both streams was dominated by Calluna moorland while the lower sections comprised either dense alluvial broadleaved forest (Girnock Burn) or native Scots Pine stands (Tanar). The Point‐Centered‐Quarter Method was used to quantify stem density (SD) and tree coverage (TC) as an indicator of channel shading comprising either dense alluvial broadleaved forest (Girnock Burn) or native Scots Pine stands (Tanar). The greatest reductions in maximum temperature (4 °C) and diel amplitude (6·6°C) were observed where TC and SD were greatest in areas of relatively dense broadleaved riparian cover. Analysis of the relationship between forest characteristics and temperature summary statistics revealed that SD and TC were significant predictors of mean and maximum temperatures, as well as daily temperature ranges for both rivers during the summer. The relationship between summer thermal indices and indicators of channel shading (SD or TC) was independent of forest type. However, as SD and TC were greater in the deciduous reaches of Glen Girnock than the mature Scots pine reaches of Glen Tanar, maximum reductions in stream temperature were greater in Glen Girnock. Given that maximum temperatures were strongly influenced by measures of shading, it suggested that riparian planting may offer a suitable mitigation against high temperatures under climate change. Copyright © 2012 John Wiley & Sons, Ltd.
Relating extremes of flow and air temperature to stream fish communities
Authors: Jones Nicholas E. , Petreman Ian C.
Published: August 2012

The disruptive potential of floods, drought, ice, and high water temperature on fishes in streams have been well documented. We examined the relationship between unexpected high flow events, low flow events coupled with low and high air temperature events, and a variety of ecological measures frequently used to quantify fish communities in streams, e.g. density. We developed a severity index to quantify concurrent extreme disturbances occurring over annual and summer periods. We anticipated that years or summers of high severity would result in changes in the fish community measures, e.g. low abundance. Despite the occurrence of severe events, there were relatively few instances of environmental severity resulting in consistent negative/positive changes in fish communities. Of the fish community measures, young‐of‐the‐year (YOY) growth was most responsive to extremes. Low flow in combination with high temperature events significantly lowered YOY growth; whereas, unexpected high flows increased growth. Unexpected high flow events were associated with a significant negative effect on fish abundance and positive effects on biomass, YOY growth, and diversity during the summer period. The predictive power of abiotic–biotic regressions from the summer time period was generally greater than that from the annual time period. We suggest that high amounts of groundwater flow into the streams may buffer the impact of extreme environmental conditions. Our methodology of measuring extremes in flow and air temperature could be implemented over much larger scales for use in long‐term monitoring impacts related to climate and land use change. Copyright © Her Majesty the Queen in Right of Canada 2012
Quantitative method for evaluating generation margin for power system planning
Authors: Su Su , Tanaka Kazuyuki
Published: August 2012

As the power system advances, the competition among the power companies becomes heated, and they seek more efficient system planning using existing facilities. Therefore, an efficient system planning method is desirable. This paper proposes a quantitative evaluation method for the (N–1) generation margin considering overload and voltage stability constraints. Concerning the generation margin related to overload, a fast solution method without recalculation of the (N–1) Y‐matrix is proposed. With reference to voltage stability, this paper proposes an efficient method of seeking the stability limit. The IEEE30 model system, composed of six generators and 14 load nodes, is employed to validate the proposed method. According to the results, the proposed method can reduce the computational cost for obtaining the generation margin related to the overload and the voltage stability limit under the (N–1) condition, and can specify the value quantitatively. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 181(4): 19–28, 2012; Published online in Wiley Online Library (wileyonlinelibrary.com). doi 10.1002/eej.21234
A Shack–Hartmann laser wavefront sensor for measuring electron density in low‐current arc
Authors: Inada Yuki , Matsumoto Hirokazu , Matsuoka Shigeyasu , Kumada Akiko , Ikeda Hisatoshi , Hidaka Kunihiko
Published: August 2012

To determine electron densities in low current arcs, a Shack–Hartmann laser wavefront sensor was developed, improved in terms of measurement accuracy, and applied to atmospheric arcs with a peak current of 0.8 kA. The electron density in the pre‐extinguishing phase was 5 × 1023 m−3 at the gap center when the instantaneous current decreased to 0.1 kA. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 181(4): 1–8, 2012; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22319
Capacity design of distributed battery storage for controlling power variation with large‐scale photovoltaic sources in distribution network
Authors: Kobayashi Yasuhiro , Sawa Toshiyuki , Gunji Keiko , Yamazaki Jun , Watanabe Masahiro
Published: August 2012

We developed a method for the design of distributed battery storage capacity for evaluating battery storage with demand–supply imbalance control in distribution systems to which large‐scale home photovoltaic power generators are connected. The proposed method is based on a linear storage capacity minimization model with design‐basis demand load and photovoltaic output time series subject to battery management constraints.

We experimentally applied the design method to a sample distribution system with substation storage and terminal area storage. The developed method successfully reveals the charge–discharge schedule and stored power variation for design‐basis demand load and photovoltaic output, satisfies the peak‐cut requirement, and pinpoints the minimum distributed storage capacity. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 181(4): 29–37, 2012; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22324
First “Click” Synthesis of the Ribbed‐Functionalized Metal Clathrochelates: Cycloaddition of Benzyl Azide to Propargylamine Iron(II) Macrobicycle and the Unexpected Transformations of the Resulting Cage Complex
Authors: Belov Alexander S. , Prikhod'ko Alexander I. , Novikov Valentin V. , Vologzhanina Anna V. , Bubnov Yurii N. , Voloshin Yan Z.
Published: August 2012

A bis(propargylamine) iron(II) cage complex was obtained in high yield by nucleophilic substitution of reactive chlorine atoms of its dichloroclathrochelate precursor with an excess of propargylamine in acetonitrile. The macrobicyclic product undergoes copper(I)‐catalyzed “click” reaction with benzyl azide giving the copper(II)‐containing complex of the bis(benzyl‐1,2,3‐triazolylmethylamine) clathrochelate ligand: the Cu2+ ion coordinates two deprotonated amino groups and two donor azaheterocyclic fragments of the ribbed substituents of the macrobicyclic ligand. Demetallation of this copper(II) complex with potassium cyanide gave target clathrochelate as a minor product. The major macrobicyclic product of this demetallation containing one inherent amino group and one benzyl‐1,2,3‐triazolylmethylamine ribbed substituent resulted from the side dealkylation reaction. The complexes obtained were characterized using elemental analysis, MALDI‐TOF mass spectrometry, IR, UV/Vis, 1H and 13C{1H} NMR spectroscopy, and by X‐ray diffraction. The geometry of their FeN6 coordination polyhedra is intermediate between a trigonal prism and a trigonal antiprism.
Synthesis and Conformational Analysis of Heterogeneous Cyclic Oligomers of 6‐Amino‐6‐deoxygalactonic Acid and Phenylalanine
Authors: Soengas Raquel G. , Fontanella Marco , Santos Jose I. , Fleet George W. J. , Jiménez‐Barbero Jesús
Published: August 2012

A series of heterogeneous oligomers based on the sugar ϵ‐amino acid 6‐amino‐6‐deoxygalactonic acid and D‐ or L‐phenylalanine have been synthesised and cyclised. The resulting cyclic heterogeneous oligomers have been analysed by molecular dynamics and NMR spectroscopy to describe their conformational and topological features. These initial studies have provided valuable insight into the structural properties of these cyclopeptides.
Practical Pd/C‐Catalysed Suzuki–Miyaura Reactions for the Preparation of 3‐Aryl‐4‐oxypyridin‐2(1H)‐ones, 3‐Aryl‐2,4‐oxypyridines and 3‐Aryl‐2,4‐oxyquinolines as Useful Intermediates for the Synthesis of Biologically Active Compounds
Authors: Lamblin Marc , Bares Hugo , Dessolin Jean , Marty Christel , Bourgougnon Nathalie , Felpin François‐Xavier
Published: August 2012

Practical heterogeneous Pd/C‐catalysed Suzuki–Miyaura cross‐coupling reactions of 3‐iodo‐4‐oxypyridin‐2(1H)‐ones, 3‐iodo‐2,4‐oxypyridines, and 3‐iodo‐2,4‐oxyquinolines with arylboronic acids are described as a useful and efficient alternative to homogeneous conditions. The methodology features ligand‐free and environmentally friendly conditions, and tolerates a wide range of boronic acids. The cross‐coupled products can be viewed as useful intermediates for the preparation of 3‐aryl‐4‐hydroxypyridin‐2(1H)‐ones, which can be used as new nucleobases for antiherpetic agents.
One‐Pot Chemoselective Bis(Suzuki–Miyaura Cross‐Coupling): Efficient Access to 3,9‐Bis[(hetero)aryl]‐4H‐pyrido[1,2‐a]pyrimidin‐4‐one Derivatives Under Microwave Irradiation
Authors: Kabri Youssef , Crozet Maxime D. , Primas Nicolas , Vanelle Patrice
Published: August 2012

A one‐pot chemoselective bis(Suzuki–Miyaura cross‐coupling) reaction under microwave irradiation is reported for the 4H‐pyrido[1,2‐a]pyrimidin‐4‐one series. First, we ascertained an initial coupling reaction that was selectively carried out at the C‐3 position of (7,9‐dichloro‐3‐iodo‐4‐oxo‐4H‐pyrido[1,2‐a]pyrimidin‐2‐yl)methyl acetate (4). Next, we developed an extremely efficient one‐pot chemoselective bis(Suzuki–Miyaura cross‐coupling) reaction, allowing us to substitute successively at the 3‐ and then at the 9‐position of compound 4 with various boronic acids.
Identification of the First Alkenyl Chiloglottone Congener
Authors: Poldy Jacqueline , Peakall Rod , Barrow Russell A.
Published: August 2012

Orchids of the genus Chiloglottis rely on sexual deception to attract a male thynnine wasp, whereupon a courtship routine results in the deposition and transfer of pollinia and subsequent pollination of the orchid. The chemical cues responsible for this behavior were recognized as a new class of natural products and efforts to synthetically prepare them, to assist in structural identification and to aid in ecological studies, have been ongoing. Most recently the first alkenylated member of this class was proposed based on GC–MS analysis of a physiologically active compound present in an orchid extract. The current work reveals synthetic efforts that provide access to diastereomerically pure unsaturated chiloglottone analogues and in combination with laboratory‐based electrophysiological assays and field‐based studies have unambiguously allowed identification of 5‐allyl‐2‐ethyl‐1,3‐cyclohexanedione (1d, chiloglottone 4) as the first alkenyl congener in the chiloglottone family. Convergent synthetic approaches, involving copper(I)‐mediated conjugate addition to a glutaconic ester converging on cadmium‐mediated desymmetrization of cyclic anhydrides or a Johnson–Claisen rearrangement of a mixed ketene acetal provided the appropriately substituted δ‐keto acids suitable for carbocyclization to furnish the required chiloglottone analogues.
Asymmetric Ion‐Pairing Catalysis of the Reversible Cyclization of 2′‐Hydroxychalcone to Flavanone: Asymmetric Catalysis of an Equilibrating Reaction
Authors: Hintermann Lukas , Dittmer Claudia
Published: August 2012

The asymmetric catalytic cyclization of the simple 2′‐hydroxychalcone (1) to flavanone (2), a model for the chalcone isomerase reaction, has been realized as a catalytic asymmetric ion‐pairing process with chiral quaternary ammonium salts (e.g., 9‐anthracenylmethlycinchoninium chloride; 9‐Am‐CN‐Cl) and NaH as small‐molecule co‐catalyst. In toluene/CHCl3 solution, the process reaches an intrinsic enantioselectivity of up to S = 14.4 (er = 93.5:6.5). The reversible reaction proceeds in two steps: A fast initial reaction approaches a quasi‐equilibrium with KR/S = 4.5, followed by a second, slow racemization phase approaching Krac = 9. A simple mechanistic model featuring a living ion‐pairing catalysis with full reversibility is proposed. Deuterium transfer from co‐solvent CDCl3 to product 2 and isolation of a Michael conjugate formed from 2 and 1 demonstrate the intermediacy of flavanone enolate ion pairs. A kinetic model shows good agreement with the experimentally observed, peculiar, time‐dependent evolution of the species concentrations and the enantiomeric excess of 2. The reaction is a chemical model of the chalcone isomerase enzymatic reaction. Furthermore, it is an ideal model for studying the characteristic behavior of reversible asymmetric catalyses close to their equilibria.