- ALKYLATION REACTIONS OF PROPARGYL ALCOHOL; IMPROVED ROUTES TO PROSTAGLANDIN α-SIDE CHAIN PRECURSORS
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Alkylation reactions of the dilithio derivative of propargyl alcohol and the lithio derivative of tetrahydropyranyl protected propargyl alcohol have been explored in order to develop improved synthetic routes to the key prostaglandin α-side chain precursor methyl 7-hydroxyhept-5-ynoate (5).The use of methyl 4-bromobutanoate or the lithium salt of 4-bromobutanoic acid in these reactions did not produce the required products whereas alkylation using trimethyl ortho-4-bromobutanoate (15) gave methyl 7-hydroxyhept-5-ynoate (5) or the corresponding THP ether (4) in good yield after orthoester hydrolysis.Procedures are also described for the transformation of alcohol (5) and THP (4) into methyl 7-bromohept-5-ynoate (1).Alcohol (5) can also be converted into methyl (Z)-7-bromohept-5-enoate (2) using literature procedures.
- Casy, Guy,Furber, Mark,Richardson, Kevan A.,Stephenson, Richard G.,Taylor, Richard J.K.
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Read Online
- Transformation of Thioacids into Carboxylic Acids via a Visible-Light-Promoted Atomic Substitution Process
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A visible-light-promoted atomic substitution reaction for transforming thiocacids into carboxylic acids with dimethyl sulfoxide (DMSO) as the oxygen source has been developed, affording various alkyl and aryl carboxylic acids in over 90% yields. The atomic substitution process proceeds smoothly through the photochemical reactivity of the formed hydrogen-bonding adduct between thioacids and DMSO. A DMSO-involved proton-coupled electron transfer (PCET) and the simultaneous generation of thiyl and hydroxyl radicals are proposed to be key steps for realizing the transformation.
- Fu, Qiang,Liang, Fu-Shun,Lou, Da-Wei,Pan, Gao-Feng,Wang, Rui,Wu, Min,Xie, Kai-Jun
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supporting information
p. 2020 - 2024
(2022/03/31)
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- The Electrophilic Fluorination of Enol Esters Using SelectFluor: A Polar Two-Electron Process
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The reaction of enol esters with SelectFluor is facile and leads to the corresponding α-fluoroketones under mild conditions and, as a result, this route is commonly employed for the synthesis of medicinally important compounds such as fluorinated steroids. However, despite the use of this methodology in synthesis, the mechanism of this reaction and the influence of structure on reactivity are unclear. A rigorous mechanistic study of the fluorination of these substrates is presented, informed primarily by detailed and robust kinetic experiments. The results of this study implicate a polar two-electron process via an oxygen-stabilised carbenium species, rather than a single-electron process involving radical intermediates. The structure–reactivity relationships revealed here will assist synthetic chemists in deploying this type of methodology in the syntheses of α-fluoroketones.
- Wood, Susanna H.,Etridge, Stephen,Kennedy, Alan R.,Percy, Jonathan M.,Nelson, David J.
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supporting information
p. 5574 - 5585
(2019/03/21)
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- Iron-Catalyzed Aerobic Oxidation of Aldehydes: Single Component Catalyst and Mechanistic Studies
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An aerobic oxidation of aldehydes towards carboxylic acids in MeCN using 1 atm of pure oxygen or oxygen in air as the oxidant and a catalytic amount of single component catalyst, Fe(NO3)3·9H2O, has been developed. Carboxylic acids with different synthetically useful functional groups were obtained at room temperature. Two mechanistic pathways have been proposed based on isotopic labeling, NMR monitoring, and control experiments. The practicality of this reaction has been demonstrated by conducting several 50 mmol-scale reactions using pure oxygen or an air-flow of ~30 mL/min.
- Jiang, Xingguo,Zhai, Yizhan,Chen, Junyu,Han, Yulin,Yang, Zheng,Ma, Shengming
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supporting information
p. 15 - 19
(2017/11/23)
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- CONDENSED HETEROCYCLIC COMPOUND HAVING CYCLOALKYLPYRIDYL GROUP OR SALT THEREOF, AGRICULTURAL AND HORTICULTURAL INSECTICIDE COMPRISING THE COMPOUND, AND METHOD FOR USING THE INSECTICIDE
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An object of the present invention is to provide and develop novel agricultural and horticultural insecticides in view of the still immense damage caused by insect pests etc. and the emergence of insect pests resistant to existing insecticides in crop production in the fields of agriculture, horticulture and the like. Provided are a condensed heterocyclic compound represented by the general formula (1): {wherein R1 represents an ethyl group, R2 represents a cycloalkyl group, R3 represents a haloalkyl group, A, A2 and A3 each represent a nitrogen atom or a CH group, A1 represents N-Me, m represents 0 or 2, and n represents 1} or a salt thereof; an agricultural and horticultural insecticide comprising the compound or a salt thereof as an active ingredient; and a method for using the insecticide.
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- Preparation method of Roxadustat
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The invention discloses a preparation method of Roxadustat. The chemical name of Roxadustat is 2-[[5-bromo-4-(4-cyclopropyl-1-naphthalene)-4H-1,2,4-triazole-3-yl] sulfo] acetic acid. The molecular formula is C17H14BrN3O2S. The preparation process is concise, raw materials are easily available and the preparation process is economical and environmentally friendly, industrialization is achieved favorably, the economical technical development of bulk pharmaceutical chemicals of Roxadustat can be promoted, the production cost is lowered, the yield is high, the environmental pollution is slight, and the method is suitable for large-scaled production.
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Paragraph 0011; 0012; 0013
(2018/04/28)
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- A method of synthesizing cyclopropanecarboxylic acid
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The invention discloses a novel method for synthesizing cyclopropanecarboxylic acid, which comprises the following steps: preparation of reaction liquid system: in a nitrogen protective atmosphere, adding 1-1.5 mol of polished dry zinc cuttings into a first solvent, adding acetyl chloride or adding cuprous chloride at 0-60 DEG C to activate for 0.5-5 hours, dropwisely adding 1 mol of 2,3-dibromopropionic acid or 2,3-dibromopropionic acid derivatives at 10-100 DEG C, keeping the temperature for 2-6 hours while refluxing, and cooling to 0-80 DEG C; and reaction preparation: in the nitrogen protective atmosphere, dissolving 0.9-1.2 mol of methylene triphenyl phosphorus alkane in 2-6 equivalent weights of first solvent while keeping the temperature, dropwisely adding into the reaction liquid system, and gradually heating to a reflux state, thereby obtaining the cyclopropanecarboxylic acid. The method shortens the three, four or five-step process into one-step reaction, thereby greatly reducing the production equipment investment and the cost on personnel and public works.
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Paragraph 0034; 0035
(2016/12/07)
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- [Ru(bpy)3]Cl2-catalyzed aerobic oxidative cleavage β-diketones to carboxylic acids under visible light irradiation
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A mild and highly efficient method for the preparation of carboxylic acids is developed through a visible-light-mediated aerobic oxidative cleavage of β-diketones. This process provides a potential general, practical and scalable protocol for both laboratory synthesis and industrial production of carboxylic acids in a green manner.
- Wang, Xiao-Yan,Shang, Zhen-Peng,Zha, Gao-Feng,Chen, Xiao-Qing,Bukhari, Syed Nasir Abbas,Qin, Hua-Li
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supporting information
p. 5628 - 5631
(2016/11/23)
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- Cooperative N-Heterocyclic Carbene (NHC) and Ruthenium Redox Catalysis: Oxidative Esterification of Aldehydes with Air as the Terminal Oxidant
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The paper describes a cooperative NHC (N-heterocyclic carbene) and ruthenium-based redox catalysis for the mild aerobic oxidative esterification of various aromatic and heteroaromatic aldehydes. The ruthenium(II) complex Ru(bpz)3(PF6)2 (bpz=2,2′-bipyrazine) as catalyst is shown to be compatible with free NHCs. The NHC is used in these cascade reactions for the umpolung of the aldehyde to form the corresponding Breslow intermediate which in turn gets oxidized to an acylazolium ion by the ruthenium redox catalyst. Air is used as a terminal oxidant for oxidation (regeneration) of the ruthenium catalyst. In addition, we will show that in the absence of the ruthenium redox catalyst and alcohol, NHC-catalyzed aerobic oxidation of aldehydes delivers the corresponding acids in good to excellent yields. Mechanistic studies and DFT calculations supporting our suggested mechanisms are provided. Copyright
- Zhao, Junfeng,Mueck-Lichtenfeld, Christian,Studer, Armido
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supporting information
p. 1098 - 1106
(2013/05/21)
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- Metal-free, hydroacylation of CC and NN bonds via aerobic C-H activation of aldehydes, and reaction of the products thereof
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In this report, a thorough evaluation of the use of aerobically initiated, metal-free hydroacylation of various CC and NN acceptor molecules with a wide range of aldehydes is presented. The aerobic-activation conditions that have been developed are in sharp contrast to previous conditions for hydroacylation, which tend to use transition metals, peroxides that require thermal or photochemical degradation, or N-heterocyclic carbenes. The mildness of the conditions enables a number of reactions involving sensitive reaction partners and, perhaps most significantly, allows for α-functionalised chiral aldehydes to undergo radical-based hydroacylation with complete retention of optical purity. We also demonstrate how the resulting hydroacylation products can be transformed into other useful intermediates, such as γ-keto- sulfonamides, sultams, sultones, cyclic N-sulfonyl imines and amides.
- Chudasama, Vijay,Akhbar, Ahmed R.,Bahou, Karim A.,Fitzmaurice, Richard J.,Caddick, Stephen
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p. 7301 - 7317
(2013/10/22)
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- Synthesis, crystal structure and bioactivity of N-(5-propyl-1,3,4- thiadiazol-2-yl)cyclopropanecarboxamide
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A new 1,3,4-thiadiazole compound with m.f. C9H 13N3OS, has been synthesized and confirmed by 1H NMR and HRMS. The single crystal structure of the 1,3,4-thiadiazole compound was determined by a single crystal X-ray diffraction study. The crystal belongs to the triclinic system, space group P-1 with a = 10.238(2), b = 10.325(2), c = 10.560(2) ?, α = 104.09(3), β = 109.50(3), γ = 93.40(3)°, Z = 4, V = 1008.4(3)?3, Mr = 211.28, Dc = 1.392 g/cm3, S = 0.98, μ = 0.29 mm-1, F(000) = 448, the final R1 = 0.0970 and wR2 = 0.2147 for 1776 were observed with I > 2Σ(I). X-ray indicated that two intermolecular hydrogen bonds N1-H1···N5, N4-H4···N2 were observed. The preliminary biological test shown that the synthesized compound has moderate herbicidal activity against Brassica campestris.
- Sun, Na-Bo,Jin, Jian-Zhong,Lei, Chao,He, Fang-Yue
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p. 7820 - 7822
(2013/09/23)
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- Synthesis, crystal structure and biological activity of N-(5-(o-tolyl)-1,3,4-thiadiazol-2-yl)cyclopropanecarboxamide
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A new 1, 3, 4-thiadiazole compound, N-(5-(o-tolyl)-1,3,4-thiadiazol-2-yl) cyclopropanecarboxamide, was synthesized and its structure was confirmed by 1H NMR, MS and HRMS. The single crystal structure of the title compound was determined by X-ray diffraction. The preliminary biological test showed that the synthesized compound has moderate herbicidal activity against Brassica campestris and fungicidal activities against Sclerotinia sclerotiorum(Lib.) de Bary, Rhizoctonia solanii, Fusarium oxysporum, Corynespora cassiicola, and Botrytis cinerea.
- Tong, Jian-Ying,Sun, Na-Bo,Wu, Hong-Ke,Liu, Xing-Hai
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p. 1349 - 1353
(2014/01/06)
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- Gold-catalyzed cycloisomerization of 1,7-enyne esters to structurally diverse cis -1,2,3,6-tetrahydropyridin-4-yl ketones
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A synthetic method that relies on gold(I)-catalyzed cycloisomerization of 1,7-enyne esters to prepare highly functionalized cis-1,2,3,6-tetrahydropyridin- 4-yl ketone derivatives in good to excellent yields and as a single regio-, diastereo-, and enantiomer is described. By taking advantage of the distinctive differences in the electronic and steric properties between an NHC (NHC = N-heterocyclic carbene) and phosphine ligand in the respective gold(I) complexes, a divergence in product selectivity was observed. In the presence of [PhCNAuIPr]+SbF6- (IPr = 1,3-bis(2,6- diisopropylphenyl)imidazol-2-ylidine) as the catalyst, tandem 1,3-acyloxy migration/6-exo-trig cyclization/1,5-acyl migration of the substrate was found to selectively occur to give the δ-diketone-substituted 1,2,3,6-tetrahydropyridine adduct. In contrast, reactions with the gold(I) phosphine complex [MeCNAu(JohnPhos)]+SbF6- (JohnPhos = (1,1′-biphenyl-2-yl)-di-tert-butylphosphine) as the catalyst was discovered to result in preferential 1,3-acyloxy migration/6-exo-trig cyclization/hydrolysis of the 1,7-enyne ester and formation of the cis-1,2,3,6-tetrahydropyridin-4-yl ketone derivative. The utility of this piperidine forming strategy as a synthetic tool that makes use of 1,7-enyne esters was exemplified by its application to the synthesis of an enantiopure analogue of the bioactive 2,3,4,4a,5,9b-hexahydroindeno[1,2-c]pyridine family of compounds.
- Rao, Weidong,Sally,Koh, Ming Joo,Chan, Philip Wai Hong
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p. 3183 - 3195
(2013/06/27)
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- COMPOSITIONS FOR TREATMENT OF CYSTIC FIBROSIS AND OTHER CHRONIC DISEASES
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The present invention relates to pharmaceutical compositions comprising an inhibitor of epithelial sodium channel activity in combination with at least one ABC Transporter modulator compound of Formula A, Formula B, Formula C, or Formula D. The invention also relates to pharmaceutical formulations thereof, and to methods of using such compositions in the treatment of CFTR mediated diseases, particularly cystic fibrosis using the pharmaceutical combination compositions.
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- PROCESS FOR THE PREPARATION OF PHARMACEUTICAL INTERMEDIATES
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The invention relates to a process for the preparation of cyclopropyl benzyl ketone compounds of formula (II) wherein R1 represents fluorine or chlorine atom or C1-4 alkoxy group, by the reaction of a Grignard reagent, obtained from the reaction of compound of formula (V), wherein X represents chlorine or fluorine atom, with the compound of formula (IV), wherein R2 represents C1-4 alkyl group, having a straight or branched chain. The process can be applied preferably on industrial scale. Compound of formula (II), wherein R represents a fluorine atom in position 2 is an intermediate of the preparation process of prasugrel, which is a platelet inhibitor used in the therapy.
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Page/Page column 13-14
(2009/07/03)
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- Synthesis, antifungal activities and 3D-QSAR study of N-(5-substituted-1,3,4-thiadiazol-2-yl)cyclopropanecarboxamides
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A series of cyclopropanecarboxamide were prepared and tested for antifungal activity in vivo. The preliminary bioassays indicated that some compounds are comparable to the commercial fungicides. To further explore the comprehensive structure-activity relationship on the basis of fungicidal activity data, comparative molecular field analysis (CoMFA) was performed, and a statistically reliable model with good predictive power (r2 = 0.8, q2 = 0.516) was achieved. Based on the CoMFA, compound 7p was designed and synthesized, which was found to display a good antifungal activity (79.38%) as 7g and 7h.
- Liu, Xing-Hai,Shi, Yan-Xia,Ma, Yi,Zhang, Chuan-Yu,Dong, Wei-Li,Pan, Li,Wang, Bao-Lei,Li, Bao-Ju,Li, Zheng-Ming
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scheme or table
p. 2782 - 2786
(2009/10/19)
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- Factor xa inhibitors with aryl-amidines and derivatives, and prodrugs thereof
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The present invention relates to a compound with aryl-amidines, particularly amidinoaryl-cyclopropanes, amidinoarylmethyl-pyrroles, amidinoaryl-benzenes, amidinoaryl-pyridines, or amindonoaryl-alanines, represented by formula (1), a pharmaceutically acceptable salt, a prodrug, a hydrate, a solvate or an isomer thereof, which are inhibitors of coagulation enzyme, factor Xa (FXa). The present invention also relates to a pharmaceutical composition containing the compound, and a method of using the same as an anticoagulant agent for treatment and prevention of thrombosis disorders.
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- Highly selective and efficient conversion of alkyl aryl and alkyl cyclopropyl ketones to aromatic and cyclopropane carboxylic acids by aerobic catalytic oxidation: A free-radical redox chain mechanism
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An efficient and convenient method has been developed for the oxidation of aryl alkyl and cyclopropyl alkyl ketones to aromatic and cyclopropane carboxylic acids by molecular oxygen at atmospheric pressure, catalysed by Mn(NQ3)2 in combination with Co(NO3)2 or Cu(NO3)2. This simple, cheap and highly selective process has a general character for the synthesis of carboxylic acids and it is particularly suitable for industrial applications.
- Minisci, Francesco,Recupero, Francesco,Fontana, Francesca,Bj?rsvik, Hans-Rene?,Liguori, Lucia
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p. 610 - 612
(2007/10/03)
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- Synthesis of a 13C labeled N-cyclopropylamine tetrahydropyridine derivative
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The synthesis of 1-(2-13C)-cyclopropyl-4-phenyl-1,2,3,6-tetrahydropyridine (8) is reported. Attempts were first made to prepare labeled cyclopropylamine via a cyclopropanation/Curtius rearrangement sequence, but the yields were too modest to be suitable for the synthesis of a labeled compound. The preparation of 8 was achieved via cyclopropanation of the N-formyl tetrahydropyridine derivative 21 using the Grignard reagent of ethyl bromide and Ti(O-iPr)4 as a catalyst. The synthesis proceeded in high yield (82%). The method has a wide potential for the synthesis of other cyclopropyl ring labeled and substituted cyclopropyl ring labeled tetrahydropyridine dervatives which can be used in Monoamine Oxidase (MAO) and Cyt P450 enzymes mechanistic studies. Copyright
- Kuttab, Simon,Mabic, Stephan
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p. 813 - 822
(2007/10/03)
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- Benzothiadiazine compounds
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Compound of formula (I): wherein: R1 represents hydroxy, RCO—O— or RCO—NRa—, R2 represents hydrogen, halogen, or hydroxy, R′CO—O or R′CO—NR′a—, R and R′, which may be identical or different, represent linear or branched (C1-C6)alkyl optionally substituted by aryl, linear or branched (C2-C6)alkenyl optionally substituted by aryl, linear or branched (C1-C6)perhaloalkyl, (C3-C7)cycloalkyl, adamantyl, aryl or heteroaryl, Ra and R′a, which may be identical or different, represent hydrogen or linear or branched (C1-C6)alkyl, linear or branched (C1-C6)perhaloalkyl, linear or branched (C1-C6)acyl, aryl or heteroaryl, its isomer and addition salts thereof with a pharmaceutically acceptable acid or base and medicinal products containing the same are useful as AMPA modulators.
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- Process for producing cyclopropanecarboxylates
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There is disclosed a process process for producing a cyclopropanecarboxylate of formula (1): 1which process comprises reacting cyclopropanecarboxylic acid of formula (2): 2with a monohydroxy compound of formula (3): R6OH??(3),in the presence of a catalyst compound comprising an element of to Group 4 of the Periodic Table of Elements.
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- Method for preparing cyclopropanecarboxylic acids
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The invention relates to a novel method for preparing cyclopropanecarboxylic acids by acidolysis of the corresponding esters, using an alkylbenzenesulfonic acid represented by the formula: as the reaction catalyst, where m+n is 5 to 15. Process-engineering improvements and simplifications are achieved with this process.
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- Oxidation of aldehydes with Oxone in aqueous acetone
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Several aldehydes have been convened to the corresponding acids in good to excellent yields. The oxidant was Oxone (potassium peroxymonosulfate), the reactions were performed in either 20% aqueous acetone, water, or aqueous acetonitrile, and buffered with sodium bicarbonate.
- Webb, Kevin S.,Ruszkay, Stephen J.
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p. 401 - 410
(2007/10/03)
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- Processes for the preparation of cyclopropanecarboxylic acid and derivatives thereof
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Disclosed is a process for the preparation of cyclopropanecarboxylic acid by the non-catalytic, oxidation of cyclopropanecarboxaldehyde using molecular oxygen as the oxidant. Also disclosed are processes for the preparation of amides, esters and acid chlorides from cyclopropanecarboxylic acid.
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- The Mechanism of RuO4-Mediated Oxidations of Ethers: Isotope Effects, Solvent Effects and Substituent Effects
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The mechanism of the RuO4-mediated oxidation of ethers to esters has been investigated.Oxidation of cyclopropylmethyl methyl ether gave methyl cyclopropanecarboxylate.No rearranged products were observed.On RuO4 oxidation of benzyl methyl ether and p-methoxybenzyl methyl ether in CCl4 with NaIO4 as stoichiometric oxidant, no chlorinated products were observed.A series of 4-substituted benzyl methyl ethers was oxidized with RuO4-NaIO4.A correlation of the rate of the reaction with Hammett ?-values gave a ρ of -1.7, indicating only a moderate charge separation in the transition state (TS).Benzyl methyl ether (1) was oxidized in a series of acetone-water mixtures.From these experiments, a Grunwald-Winstein m-value of 0.11 was obtained, indicating a non-polar TS for the reaction.PhCHDOCH3 (2) and PhCD2OCH3 (3) were oxidized and two deuterium isotipe effects, one of 6.1+/-0.4 and another of 1.3+/-0.1 were obtained.If one assumes a one-step reaction mechanism, the value of 1.3 would be a large α-secondary isotope effect, indicating a change in the hybridization of the benzylic carbon during the reaction. α-Methylbenzyl methyl ether (4) was oxidized at a seventh of the rate of 1, despite the fact that 4 would have given a more stable carbocation than 1.These conflicting pieces of evidence are difficult to rationalise with a hydride or hydrogen abstraction mechanism.Instead it is proposed that the reaction proceeds by either a concerted reaction or by a reversible oxidative addition of the ether to RuO4 followed by a slow concerted step to give the product.
- Bakke, Jan M.,Froehaug, Astrid E.
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p. 615 - 622
(2007/10/02)
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- RETROVIRAL PROTEASE INHIBITORS
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Urea-containing hydroxyethylamine peptide compounds are effective as retroviral protease inhibitors, and in particular as inhibitors of HIV protease.
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- Drug delivery studies in Caco-2 monolayers. Synthesis, hydrolysis, and transport of O-cyclopropane carboxylic acid ester prodrugs of various β-blocking agents
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A series of O-cyclopropane carboxylic acid ester prodrugs of various β-blocking agents was synthesized. All prodrugs were hydrolyzed to give their parent compounds in aqueous phosphate buffer of pH 7.4 and in 80% human plasma. The half-lives in buffer solutions varied from 4 hours for the timolol prodrug to about I day for the prodrug of alprenolol. In human plasma the half-lives were shorter, ranging from 1 to 7 hours. The formation of the O-cyclopropane carboxylic acid ester derivatives significantly increased the lipophilicities of the β-blockers as measured by the distribution coefficient between n-octanol and aqueous phosphate buffer of pH 7.4. To characterize the biomembrane permeability characteristics of the β-blockers, transport properties across Caco-2 cell monolayers were investigated. An increase in lipophilicity resulted in a higher permeability of the prodrugs as compared to the parent compounds. Hence, acebutolol experienced an increment of a factor 17 on the apparent permeability coefficient, Papp, whereas Papp for the more lipophilic drug propranolol was increased by a factor of only 1.26. Some conversion of the prodrugs to their parent compounds was observed during the transport and appeared to be due to enzymatic intracellular metabolism.
- Hovgaard,Brondsted,Buur,Bundgaard
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p. 387 - 392
(2007/10/03)
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- Isolation of cis-isomers from isomeric mixtures of cis/transcyclopropanecarboxylates
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The treatment of isomeric mixtures of cis/trans -3-(2,2-dihalo-3,3,3-trifluoropropyl)-2,2-dimethylcyclopropanecarboxylic acid esters with excess base at elevated temperatures hydrolyzes the ester, dehydrohalogenates the side chain, and thereafter selectively converts the resulting unsaturated side chain of the corresponding trans-cyclopropanecarboxylic acid to an acetyl byproduct, from which may be readily separated and recovered an enriched concentration of the desired cis-2-halo-1-propenylcyclopropanecarboxylic acid, together with minor amounts of the corresponding transacid.
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- SELECTIVE HYDROLYSIS OF NITRILES UNDER MILD CONDITIONS BY AN ENZYME
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A wide range of aromatic/aliphatic nitriles and dinitriles have been selcetively hydrolysed using a commercially available enzyme preparation from a Rhodococcuc sp.
- Cohen, Mark A.,Sawden, Janette,Turner, Nicholas J.
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p. 7223 - 7226
(2007/10/02)
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- Novel cyclopropane carboxylates
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Novel stereoisomers or mixtures of stereoisomers of compounds of the formula STR1 wherein R is the residue of an alcohol used in the pyrethrinoid field having remarkable pesticidal properties and being surprisingly stable.
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- Selective, Heterogeneous Oxidation of Alcohols and Diols with Potassium Permanganate
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Primary alcohols can be conveniently oxidized to carboxylic acids using solid KMnO4/CuSO4*5H2O/KOH in an organic solvent; 1,4- and 1,5-diols can be selectively oxidized to the corresponding lactones using appropriate mixtures of KMnO4/CuSO4*5H2O without added base.
- Jefford, Charles W.,Wang, Ying
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p. 634 - 635
(2007/10/02)
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- Kinetics of Cyclopropyl Radical Reactions. 3. Study of Some 1-Substituted Cyclopropyl Radicals by EPR Spectroscopy. The Inversion Barrier for 1-Methylcyclopropyl
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The 1-methyl-, 1-ethoxy-, and 1-chlorocyclopropyl radicals have been observed by low-temperature EPR spectroscopy in "frozen" configurations in which the ring hydrogens that are syn and anti to the unpaired elecron's orbital have different hyperfine splittings.The aH(syn)/aH(anti) ratios are 1.5 (CH3), 1.8 (EtO), and 1.9 (Cl), all considerably lower than the ratio of ca. 3.3 found by Kawamura et al. for methyl-substituted 1-fluorocyclopropyl radicals.The out-of-plane angles of the 1-substituent have been calculated from measured a13Cα values to be 22.5 deg (cyclopropyl), 22.9 deg (CH3), 29.1 deg (EtO), and 5.8 deg (MeSi).These angles are considerably smaller than those that have been calculated for some of these radicals by ab initio and other methods.Variable-temperature EPR spectroscopy on 1-methylcyclopropyl yields the following Arrhenius equation for its inversion: log (kinv/s-1) = (13.1 +/- 0.3) - (3.1 +/- 0.2)/2.3RT kcal/mol.For 1-ethoxycyclopropyl the rate constant for rotation about the .C-OEt bond can be represented by log (krot/s-1) = (12.5 +/- 0.2) - (5.8 +/- 0.2)/2.3RT.The barrier to inversion of this radical is >/= 9 kcal/mol.The 1-chlorocyclopropyl radical could only be observed at very low temperatures.
- Deycard, S.,Hughes, L.,Lusztyk, J.,Ingold, K. U.
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p. 4954 - 4960
(2007/10/02)
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- Cycloheptadiene derivatives
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Cycloheptadiene analogues of arachidonic acid as well as their cyclopropyl intermediates are described as inhibiting human leukocyte lipoxygenase and antagonizing SRS-A. Methods of manufacture and pharmaceutical compositions are described. The compounds are useful in treating allergic diseases, cardiovascular diseases and immunoinflammatory diseases.
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- A NOVEL RING CLEAVAGE REACTION OF OXAZOLINES
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An oxazoline can be cleanly converted to the parent carboxylic acid by treatment with NaOCl, followed by mild basic hydrolysis of the intermediate ester product(s).
- Levin, Jeremy I.,Weinreb, Steven M.
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p. 2347 - 2350
(2007/10/02)
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- Gasphasen-Reaktionen, 21. Thermische Erzeugung von Alkyl- und Halogenketenen
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Thermal gas phase reactions for the generation of ketenes can be optimized PE-spectroscopically.To eliminate HX from acetyl derivatives R2CH-COX increasing temperatures are required in the sequence HO2CCH3 ca.HCl HBr H2O ca.ROH CH4.By adding NH3, HCl can be removed from the gaseous mixture and thus the PE spectra of pure alkyl ketenes R2C=C=O (R e.g.H, CH3, C2H5) may be recorded. "Fulvene ketene" (4) is obtained from cyclopentadienecarbonyl chloride (this from the dimer) and ethyleneketene (7) by pyrolysis of cyclopropyl spirosubstituted Meldrum's acid (6).Chloro- and bromoketenes are generated as follows: ClHC=C=O from ClH2C-COCl, Cl2C=C=O from Cl3C-COBr with Zn, BrHC=C=O from 2-bromocyclobutanone and NC-HC=C=O from NC-HC=C=O from NC-H2C-COCl.The PE spectra are assigned by radical cation state comparison based on MNDO calculations.
- Bock, Hans,Hirabayashi, Takakuni,Mohmand, Shamsher
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p. 2595 - 2608
(2007/10/02)
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Cyclopropanols 5, 6 and 2 with substituent groups (-CH2OH, -CH2OTs, -CH2Br) in the 1-position, and oxaspiropentane 8, have been prepared from methylenecyclopropane. Cyclopropanols with vinyl groups in the 1-position (1-vinyl 12, 1-cyclopentenyl 13 and 1-cyclohexenyl 14) and 1-cyclopropylcyclopropanol 20 have been prepared from 1, 3-dichloroacetone. Each of the compounds readily undergoes ring expansion to the corresponding cyclobutanones. The reaction provides a simple route to cyclobutanones, the parent ketone itself being easily obtained from oxaspiropentane 8.
- Salaun,Garnier,Conia
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p. 1413 - 1421
(2007/10/10)
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