- Competitive reactions of nucleophiles. Solvolyses of cyclopropylcarbinyl and cyclobutyl methanesulfonates in the presence of NaBH4
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Cyclopropylcarbinyl (I) and cyclobutyl (II) mesylates were solvolysed in aqueous diglyme with or without added NaBH4 under a variety of conditions. The reaction products were isolated and analyzed by VPC. A mixture containing cyclopropylcarbinyl, cyclobutyl and minor quantities of homoallyl products, was obtained in all cases. The proportion of the unsaturated compound was greater in hydrocarbon than in carbinol products, the composition of the mixture depending upon reaction conditions and the starting mesylate. Thus, solvolysis of both I and II yielded cyclopropylcarbinol and cyclobutanol in a ratio of nearly 1:1, while in the hydrocarbon products methylcyclopropane predominated over cyclobutane by a factor of 3 in the reactions of I and by a factor of 2 in the reactions of II. It was shown that a direct displacement reaction of the BH4 ion on the primary mesylate I is not competitive with the solvolysis and cannot therefore be responsible for the above results. It was found that a better yield in hydrocarbons was obtained with I and II than with (1-methylcyclopropyl)carbinyl (III) and 1-methylcyclobutyl (IV) mesylates. The unexpected fact that the BH4- ion competes more efficiently with water for intermediates formed in solvolyses of I and II than for those of III and IV was confirmed by determination of competition factors of N3- ion vs water. In all cases, intermediates formed from I and II showed more discrimination in their reactions with reagents differing in nucleophylicity than did those formed from III and IV. The results indicate that the attack of the nucleophile occurs mostly on the ion pair formed in the rate determining step. The latter reaction is apparently subject to reactivity relationships typical for a direct displacement reaction and not characteristic for free carbonium ions. These facts should be borne in mind when conclusions concerning the structure of carbonium ions are drawn from the composition and structure of solvolysis products. It is concluded that the ion pairs trapped by NaBH4 have different structures, depending upon the starting isomeric mesylate. It is shown that the formation of an equilibrating mixture of classical ions or ion pairs as intermediates in these reactions cannot account for experimental results.
- Majerski,Borcic,Sunko
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Read Online
- Efficient and chemoselective hydrogenation of aldehydes catalyzed by well-defined PN3-pincer manganese(ii) catalyst precursors: An application in furfural conversion
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Well-defined and air-stable PN3-pincer manganese(ii) complexes were synthesized and used for the hydrogenation of aldehydes into alcohols under mild conditions using MeOH as a solvent. This protocol is applicable for a wide range of aldehydes containing various functional groups. Importantly, α,β-unsaturated aldehydes, including ynals, are hydrogenated with the CC double bond/CC triple bond intact. Our methodology was demonstrated for the conversion of biomass derived feedstocks such as furfural and 5-formylfurfural to furfuryl alcohol and 5-(hydroxymethyl)furfuryl alcohol respectively.
- Gholap, Sandeep Suryabhan,Dakhil, Abdullah Al,Chakraborty, Priyanka,Li, Huaifeng,Dutta, Indranil,Das, Pradip K.,Huang, Kuo-Wei
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supporting information
p. 11815 - 11818
(2021/11/30)
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- Synthesis method of cyclobutanone
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The invention provides a synthesis method of cyclobutanone. The method taking cyclopropanecarboxylic acid as a raw material comprises the following steps: reducing the raw material into cyclopropylmethanol, rearranging the cyclopropylmethanol under an acidic condition to obtain cyclobutanol, and carrying out TEMPO oxidation to obtain cyclobutanone. The method has the following advantages: the rawmaterials are cheap, the operation is simple, the total yield is high, and the product with the purity of 99% can be obtained through simple post-treatment. The method produces less three wastes and is suitable for large-scale production.
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Paragraph 0015
(2020/06/02)
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- Selective hydrogenation of primary amides and cyclic di-peptides under Ru-catalysis
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A ruthenium(II)-catalyzed selective hydrogenation of challenging primary amides and cyclic di-peptides to their corresponding primary alcohols and amino alcohols, respectively, is reported. The hydrogenation reaction operates under mild and eco-benign conditions and can be scaled-up.
- Subaramanian, Murugan,Sivakumar, Ganesan,Babu, Jessin K.,Balaraman, Ekambaram
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supporting information
p. 12411 - 12414
(2020/10/30)
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- Metal complex catalysts and method for catalytically reducing carboxylic acids
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The invention relates to a metal complex catalyst, which contains at least one of metal complexes with a chemical formula comprising a structural unit represented by a formula I. According to the invention, the center metal of the metal complex catalyst is iridium, and the metal complex catalyst is composed of pentamethylcyclopentadienyl, a bitetrahydropyrimidine ligand and proper coordination anions; the metal complex catalyst has activity on a carboxylic acid reduction reaction, and a carboxylic acid compound is reduced into an alcohol compound in the presence of hydrogen; and the method ismild in reaction condition, can be carried out at room temperature, and is good in catalytic performance and high in reduction product yield.
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Paragraph 0156; 0159; 0160; 0178; 0179
(2020/06/20)
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- The reductive deaminative conversion of nitriles to alcohols using: Para -formaldehyde in aqueous solution
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We report herein, for the first time, the application of para-formaldehyde (pFA) to the reductive deamination of both aliphatic and aromatic nitriles in aqueous solution under transfer hydrogenation conditions. A broad range of primary alcohols have been synthesized selectively with very good to excellent yields under the optimized conditions. The study disclosed that the air-stable, inexpensive and commercially available catalyst [Ru(p-cymene)Cl2]2 acts as the catalyst precursor in this reaction, converting to other more active catalytic species in the presence of pFA, resulting in its degradation to CO2 and H2. Nitriles are also showed to play a dual role in this transformation, both as a substrate and as a ligand, where the dimeric catalyst structures convert to monomeric ones upon the coordination of nitrile molecules.
- Tavakoli, Ghazal,Prechtl, Martin H. G.
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p. 6092 - 6101
(2019/11/11)
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- Visible-Light-Mediated Aerobic Oxidation of Organoboron Compounds Using in Situ Generated Hydrogen Peroxide
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A simple and general visible-light-mediated oxidation of organoboron compounds has been developed with rose bengal as the photocatalyst, substoichiometric Et3N as the electron donor, as well as air as the oxidant. This mild and metal-free protocol shows a broad substrate scope and provides a wide range of aliphatic alcohols and phenols in moderate to excellent yields. Notably, the robustness of this method is demonstrated on the stereospecific aerobic oxidation of organoboron compounds.
- Weng, Wei-Zhi,Liang, Hao,Zhang, Bo
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supporting information
p. 4979 - 4983
(2018/08/24)
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- Method for preparing cyclopropyl carbinol
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The invention relates to the field of organic synthesis, and discloses a method for preparing cyclopropyl carbinol. Cyclopropanecarboxylic acid ester is taken as a raw material and dissolved in a polar solvent, sodium borohydride is added, after the temperature is reduced to 0-5 DEG C, a lewis acid catalyst is added under the ordinary pressure, reduction reaction is carried out, a quenching agentis added to destroy unreacted sodium borohydride, undissolved substances are filtered, and filtrate is rectified after concentration to obtain a product. The method for preparing the cyclopropyl carbinol has the advantages that the adopted raw materials are obtained easily, the cost is low, high temperature, high pressure and other hazardous reaction conditions are not needed, the reaction conditions are mild, post-processing is simple, the post-processing produces few three wastes, and the method accords with the requirements of green chemistry. In addition, the obtained product has good yield and high purity.
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Paragraph 0021-0024
(2018/09/29)
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- Method for synthesizing cylopropylmethyl chloride by using cyclopropanemethanol
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The invention relates to the field of organic synthesis and discloses a method for synthesizing cylopropylmethyl chloride by using cyclopropanemethanol. The method comprises the following steps: (A) dissolving cyanuric chloride into a solvent A to obtain a solution; (B) dropwise adding the cyclopropanemethanol into the prepared solution for reacting; (C) adding a reaction solution finished the reaction into an alkali solution for quenching; (D) extracting a target product by using a solvent B, drying and rectifying to obtain a product. According to the method, the cyclopropanemethanol and the cyanuric chloride are used as raw materials, and are easy to obtain, low in cost and less in pollution; in addition, the method has the advantages of mild reaction conditions, simple post treatment and suitability for industrial production.
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Paragraph 0060-0065
(2017/11/29)
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- On the role of pre- and post-electron-transfer steps in the SmI 2/Amine/H2O-mediated reduction of esters: New mechanistic insights and kinetic studies
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The mechanism of the SmI2-mediated reduction of unactivated esters has been studied using a combination of kinetic, radical clocks and reactivity experiments. The kinetic data indicate that all reaction components (SmI2, amine, H2O) are involved in the rate equation and that electron transfer is facilitated by Bronsted base assisted deprotonation of water in the transition state. The use of validated cyclopropyl-containing radical clocks demonstrates that the reaction occurs via fast, reversible first electron transfer, and that the electron transfer from simple Sm(II) complexes to aliphatic esters is rapid. Notably, the mechanistic details presented herein indicate that complexation between SmI2, H2O and amines affords a new class of structurally diverse, thermodynamically powerful reductants for efficient electron transfer to carboxylic acid derivatives as an attractive alternative to the classical hydride-mediated reductions and as a source of acyl-radical equivalents for C-C bond forming processes. Electron donors: The mechanism of the SmI 2-mediated reduction of unactivated esters has been studied by using a combination of kinetic, radical clock, and reactivity experiments. Notably, the mechanistic details presented herein indicate that complexation between SmI2, H2O, and amines gives a new class of structurally diverse, thermodynamically powerful reductants for efficient electron transfer to carboxylic acid derivatives as an attractive alternative to the classical hydride-mediated reductions and as a source of acyl-radical equivalents for C-C bond-forming processes (see scheme).
- Szostak, Michal,Spain, Malcolm,Procter, David J.
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supporting information
p. 4222 - 4226
(2014/05/06)
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- Mechanism of SmI2/amine/H2O-promoted chemoselective reductions of carboxylic acid derivatives (esters, acids, and amides) to alcohols
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Samarium(II) iodide-water-amine reagents have emerged as some of the most powerful reagents (E° = -2.8 V) for the reduction of unactivated carboxylic acid derivatives to primary alcohols under single electron transfer conditions, a transformation that had been considered to lie outside the scope of the classic SmI2 reductant for more than 30 years. In this article, we present a detailed mechanistic investigation of the reduction of unactivated esters, carboxylic acids, and amides using SmI2-water-amine reagents, in which we compare the reactivity of three functional groups. The mechanism has been studied using the following: (i) kinetic, (ii) reactivity, (iii) radical clock, and (iv) isotopic labeling experiments. The kinetic data indicate that for the three functional groups all reaction components (SmI2, amine, water) are involved in the rate equation and that the rate of electron transfer is facilitated by base assisted deprotonation of water. Notably, the mechanistic details presented herein indicate that complexation between SmI2, water, and amines can result in a new class of structurally diverse, thermodynamically powerful reductants for efficient electron transfer to a variety of carboxylic acid derivatives. These observations will have important implications for the design and optimization of new processes involving Sm(II)-reduction of ketyl radicals. (Chemical Equation Presented).
- Szostak, Michal,Spain, Malcolm,Eberhart, Andrew J.,Procter, David J.
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p. 11988 - 12003
(2015/01/16)
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- Lanthanum metal-assisted cyclopropanation of alkenes with gem-dihaloalkanes
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It was confirmed that lanthanum metal was an efficient reagent for the reductive dehalogenation of gem-dihaloalkanes. When gem-dihaloalkanes were allowed to react with lanthanum metal in the presence of alkenes, cyclopropanation of the alkenes occurred under mild conditions giving the corresponding cyclopropanes in moderate to good yields.
- Nishiyama, Yutaka,Tanimizu, Hana,Tomita, Tsuyoshi
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p. 6405 - 6407
(2008/02/12)
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- A highly efficient, mild, and selective cleavage of beta-methoxyethoxymethyl (MEM) ethers by cerium(III) chloride in acetonitrile.
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[structure: see text]. A highly selective cleavage of MEM ethers has been achieved in high yields using CeCl3.7H2O in refluxing acetonitrile under mild and neutral reaction conditions. The method is very rapid and compatible with other hydroxyl protecting groups such as Bn, TBDPS, Ac, Me, Tr, PMB, benzylidene, THP, MOM, BOM, and NHAc present in the substrate.
- Sabitha,Babu,Rajkumar,Srividya,Yadav
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p. 1149 - 1151
(2007/10/03)
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- Photodecarbonylation of chiral cyclobutanones
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Triplet photosensitized irradiation of 2(S),3(R)-bis[(benzoyloxy)methyl]cyclobutanone gave optically pure (-)E-1(S),2(S)-bis(benzoyloxymethyl)cyclopropaneas a major product in the nonpolar fraction along with its stereoisomer and cycloelimination products. The absolute stereochemistry of the chiral cyclopropane was established by independent synthesis and X-ray crystal structure determination of a synthetic precursor. The distribution of decarbonylation and cycloelimination products was inversely dependent on the concentration of the substrate. Irradiation of the same ketone in tetrahydrofuran or benzene gave mostly cycloelimination products. Addition of Michler's ketone increased the ratio of photodecarbonylation, suggesting a triplet state pathway for this process. This was corroborated by the addition of dicyanoethylene, which showed significant quenching of photodecarbonylation. Irradiation of 2(S)-[(benzoyloxy)methyl]cyclobutane in acetone gave the corresponding cyclopropane as the principal product.
- Ramnauth, Jailall,Lee-Ruff, Edward
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p. 518 - 522
(2007/10/03)
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- Facile activation of zinc. Preparation of cyclobutanones via dichloroketene and cyclopropanes using the Simmons-Smith reaction
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Zinc powder activated by heating in an inert atmosphere gave good yields when used for the title reactions. The very easy work up procedure for the cyclobutanones further increases the potential of the method.
- Stenstrom
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p. 2801 - 2810
(2007/10/02)
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- Palladium(II)-Catalyzed Cyclopropanation of Simple Allyloxy and Allylamino Compounds and of 1-Oxy-1,3-butadienes with Diazomethane
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(Alkyloxymethyl)-, (aminomethyl)-, (2-alkoxyethenyl)-, (2-acetoxyethenyl)-, and (2-siloxyethenyl)cyclopropanes are obtained in high yields by reaction of allyl alcohol or derivatives, allylamines, 1-alkoxy-, 1-acetoxy-, and 1-trimethylsiloxy-1,3-butadienes with diazomethane in dichloromethane/diethylether in the presence of bis(benzonitrile)palladium dichloride.
- Tomilov, Yu. V.,Kostitsyn, A. B.,Shulishov, E. V.,Nefedov, O. M.
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p. 246 - 248
(2007/10/02)
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- NEW ORGANOCOPPER REAGENTS PREPARED UTILIZING HIGHLY REACTIVE COPPER
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Highly reactive copper solutions have been prepared by the lithium naphthalide reduction of copper(I) iodide/trialkylphosphine complexes.These activated copper solutions will react with organic halides under very mild conditions to form stable organocopper reagents.Significantly, the organocopper reagents can contain considerable functionalities such as ester, nitrile, chloride, epoxide, and ketone groups.These functionalized organocopper species undergo many reactions typical of other organocopper species.Intermolecular 1,4-additions, epoxide-opening reactions, and ketone formation with acid chlorides have been successfully achieved.In addition, this methodology has been applied to an intramolecular epoxide-cleavage reaction.The influence of the connecting chain length, substitution pattern, reaction solvent, and CuI/phosphine complex upon the regioselectivity of the intramolecular cyclization is described.
- Rieke, Reuben D.,Wehmeyer, Richard M.,Wu, Tse-Chong,Ebert, Greg W.
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p. 443 - 454
(2007/10/02)
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- REACTIONS OF DIAZOALKANES WITH UNSATURATED COMPOUNDS. 8. CATALYTIC CYCLOPROPANATION OF ALLYL ALCOHOLS AND ALLYLAMINES WITH DIAZOMETHANE
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Allyl alcohols and allylamines have been cyclopropanated directly with diazomethane in the presence of palladium compounds to give 60-88percent of cyclopropylmethanols and cyclopropylmethylamines, respectively, almost free from the products of formal insertion of methylene into the heteroatom-hydrogen bond.
- Tomilov, Yu. V.,Kostitsyn, A. B.,Dokichev, V. A.,Dzhemilev, U. M.,Nefedov, O. M.
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p. 2518 - 2521
(2007/10/02)
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- REACTIONS OF DIAZOALKANES WITH UNSATURATED COMPOUNDS. 6. CATALYTIC CYCLOPROPANATION OF UNSATURATED HYDROCARBONS AND THEIR DERIVATIVES WITH DIAZOMETHANE
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A systematic study has been conducted of the catalytic reaction of diazomethane with cyclic and polycyclic unsaturated hydrocarbons, conjugated dienes, as well as with a series of functionalized unsaturated conpounds.The feasibility of using transition metal, nontransition metal, and rare earth metal compounds of, for example, Co, Ni, Zr, Rh, and Dy, has been demonstrated for the first time.It has also been established that Pd(acac)2 has very high activity as a catalyst for the cyclopropanation of terminal and endocyclic double bonds by diazomethane, and that its activity is reduced upon the introduction of n-donor ligands or in the presence of strong polar solvents.
- Dzhemilev, U. M.,Dokichev, V. A.,Sultanov, S. Z.,Khusnutdinov, R. I.,Tomilov, Yu. V.,et al.
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p. 1707 - 1714
(2007/10/02)
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- DIRECT FORMATION OF EPOXYALKYLCOPPER REAGENTS FROM ACTIVATED COPPER AND EPOXYALKYL BROMIDES AND THEIR INTRAMOLECULAR CYCLIZATIONS
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Epoxyalkylcopper compounds have readily been prepared by the direct oxidative addition of active copper to epoxyalkyl halides.The intramolecular cyclization of the epoxyalkylcopper reagents via an epoxide cleavage process is described.Significantly, many functional groups can be present in the bromoepoxides yielding highly functionalized carbocycles.The regioselectivity of this cyclizations is affected by the connecting chain length, substitution pattern, reaction solvent, and the CuI-phosphine complex used to generate the copper.
- Wu, Tse-Chong,Rieke, Reuben D.
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p. 6753 - 6756
(2007/10/02)
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- Antihypertensive 1,4-dihydropyridines having a conjugated ester
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1,4-dihydropyridine derivatives represented by the following general formula, STR1 in which R3 is a combination of an unsaturated straight chain hydrocarbon group or derivative thereof connected by a single bond with an unsaturated hydrocarbon group or derivative thereof so that the unsaturated carbon atoms of the two groups are in conjugated relationship. These compounds have a hypotensive action the effective time of which is long, which makes the blood pressure descend slowly, and the toxicity of which is low.
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- Deamination Reactions, 46. - Decomposition of 1-Alkenylcyclopropanediazonium Ions
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1-(2-Propenyl)- (10a), 1-(2-methyl-2-propenyl)- (10b), and 1-(3-butenyl)cyclopropanediazonium ions (35) have been generated by alkaline cleavage of the analogous nitrosocarbamates in methanol.Their major reaction paths are cyclopropyl-allyl tranformation (67 - 81percent), elimination to give alkylidenecyclopropanes (13 - 21percent), nucleophilic displacement (4 - 6percent), and 1,2-H shift (1 - 5percent).Participation of the double bond with formation of spirocyclic products was found to be small (0.5 - 1.2percent) with 10a, b and negligible with 35.The 2-methylene-5-hexenyl cations (39) arising from 35 underwent cyclization (intramolecular electrophilic addition, 39 --> 42) in competition with nucleophilic capture, but did not undergo a degenerate Cope rearrangement (39 39').
- Kirmse, Wolfgang,Rode, Klaus
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p. 839 - 846
(2007/10/02)
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- REGIOCHEMISTRY OF THE METAL-HALOGEN EXCHANGE INDUCED CYCLIZATION OF ω-IODOEPOXIDES
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The regiochemistry of the cyclization reactions of some ω-lithioepoxides as a function of chain length and substitution pattern has been examined.Striking changes in regiochemistry have been observed in the presence of certain Lewis acids and metal halides.
- Cooke, Manning P.,Houpis, Ioannis N.
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p. 3643 - 3646
(2007/10/02)
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- Scope, Limitation, and Mechanism of the Homoconjugate Electrophilic Addition of Hydrogen Halides
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Hydrogen halides (HCl, HBr, HI) add by a homoconjugate 1,5 mechanism to cyclopropanes carrying certain electron-withdrawing substituents.When the substituent is COCH3, COC6H5, CO2H, or CN, the reaction gives the 1,3-disubstituted propane in high yield.Addition of DCl gives a product with deuterium only in the position α to the substituent.The order of rates is not in agreement with a mechanism whereby the cyclopropane ring is protonated initially, since the rate of such a process should be slowed by electron-withdrawing groups.The ketones, however, react much more rapidly than benzylcyclopropane, a model for the direct protonation mechanism.The homoconjugate mechanism involves rapid protonation of the side chain, followed by nucleophilic attack on the cyclopropane ring.The reaction is limited to substrates that can be protonated on the side chain to produce an intermediate with charge ajacent to the cyclopropane ring.This charge must be able to be transmitted by resonance to the unsubstituted ring positions in order to facilitate the nucleophilic step.
- Lambert, Joseph B.,Napoli, James J.,Johnson, Katharine Kappauf,Taba, Kalulu N.,Packard, Beverly Sue
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p. 1291 - 1295
(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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- Regioselective Route to Sterically Hindered Cyclopropylcarbinyl Halides
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Reaction of cyclopropylcarbinyl alcohols 1 with hexachloroacetone and triphenylphosphine resulted in 80 - 90 percent yields of the corresponding cyclopropylcarbinyl chlorides 4 regioselectively, with no trace of the homoallylic chloride 2 or the chlorocyclobutane derivative 6a.Similar reaction of 1 with bromine and triphenylphosphine, in dimethylformamide, gave 65 - 80 percent yields of the cyclopropylcarbinyl bromide 5 with trace amounts of the homoallylic bromide 3 but no detectable bromocyclobutane derivative 6b.These reactions are amenable to the preparation of very sterically hindered cyclopropylcarbonyl halides, heretofore inaccessible, regioselectively and in a facile manner.
- Hrubiec, Robert T.,Smith, Michael B.
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p. 431 - 435
(2007/10/02)
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- Solvent Effects on Solvolytic Reactivity. A Diagnostic Test for Neighboring-Group Assistance by ? Conjugation in Solvolysis Reactions
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The solvolysis rates of 13 arenesulfonates have been determined in mixtures of ethanol and water (the E-series solvents) and acetic acid and formic acid (the A-series solvents).The substrates studied include the following: neophyl (1), 2-adamantyl (2), neopentyl (3), and cyclooctyl (4) tosylates; cyclopropylcarbinyl pemsylate (5a) and tosylate (5b); exo-2-norbornyl tosylate (6); cyclobutylcarbinyl (7), cyclobutyl (8), and pinacolyl (9) brosylates; cyclopentyl (10), cyclohexyl (11), and 2-propyl (12) tosylates; and cyclopentylcarbinyl brosylate (13).Correlations of the rate data by eq 1 t(Y) = a + b log kt(neophyl-OTs)> showed that the various substrates responded differently to the examined solvent effects on the solvolytic reactivity.For compounds 2-4, linear correlations were obtained.For compounds 5-9, E-line, A-line dispersions were noted which diverged with increasing ionizing power; for compounds 10-12, parallel E-line, A-line dispersions were obtained; and for compound 13, an E-line, A-line dispersion was observed which converged with increasing ionizing power.Stastistical analyses of the rate data correlations confirmed the significance of the E or A classification of data.The results are interpreted in terms of differences in the involvement of solvent in the transition state for those solvolyses assisted by bridging from those assisted by C-C ? bond hyperconjugation.
- Roberts, Donald D.
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p. 2521 - 2526
(2007/10/02)
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- Latent Inhibitors. Part 3. The Inhibition of Lactate Dehydrogenase and Alcohol Dehydrogenase by Cyclopropane-containing Compounds
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A series of monocyclic and bicyclic cyclopropylmethanols typified by bicycloheptan-7-ylmethanol is shown to comprise latent irreversible inhibitors of horse liver alcohol dehydrogenase (E.C.1.1.1.1) with inhibitory properties related to the ability of the inhibitor to bind to the enzyme.The time course of inhibition is biphasic, a property shared by a number of unsaturated aldehydes, ketones, and alcohols.Kinetic studies also suggest that inhibition occurs most effectively during the removal of hydride from the inhibitor as oxidation takes place.Analogous properties were found for the inhibition of lactate dehydrogenase (E.C.1.1.1.27) by cyclopropylglycolic acid.
- Maclnnes, Iain,Nonhebel, Derek C.,Orszulik, Stefan T.,Suckling, Colin J.,Wrigglesworth, Roger
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p. 2771 - 2776
(2007/10/02)
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- Oxidations of Cyclopropane, Methylcyclopropane, and Arenes with the Mono-oxygenase System from Methylococcus capsulatus
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The mono-oxygenase system from Methylococcus capsulatus oxidises cyclopropane to cyclopropanol, methylcyclopropane to cyclopropylmethanol, and monosubstituted benzenes to para-substituted phenols (with accompanying NIH shift).
- Dalton, Howard,Golding, Bernard T.,Waters, Barry W.,Higgins, Raymond,Taylor, John A.
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p. 482 - 483
(2007/10/02)
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- Acid-Catalyzed Decomposition of Trialkyltriazenes: Protected Alkyldiazonium Ions
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The ecid-catalyzed decomposition of 1,3-di-n-butyl-3-methyltriazene and the synthesis and decomposition of 1,3-bis(cyclprpopylcarbinyl)-3-methyltriazene are reported.A kinetic study of the acid-catalyzed decomposition of 1,3-di-n-butyl-3-methyltriazene indicates that the reaction is subject to general acid catalysis.The rates of reaction have been studied by monitoring the disappearance of a triazene UV absorption band (263 nm).A plot of the buffer concentration vs. kobsd was a straight line, whose slope gave kcat = 1.84 *10-2 min-1M-1.A linear dependence of the log (kobsd) on pH (6.9 - 8.4) was observed, along with a solvent isotope effect (kD/kH) of 2.05.The products of the decomposition of the butyltriazene (n-butyl and sec-butyl alcohols and 1- and 2-butene) were accounted for by the intermediacy of a diazonium ion.The mechanism was corroborated by the product analysis of the decomposition of the (cyclopropylcarbinyl)triazene.The alcoholic products isolated were cyclopropylcarbinyl alcohol (48percent), cyclobutyl alcohol (48percent) and 3-buten-1-ol (4percent).This distribution is conclusive evidence that these trialkyltriazenes decompose in aqueous media to produce alkyldiazonium ions or directly to prduce carbonium ions in cases where the alkyl group is capable of stabilizing a positive charge.
- Sieh, David H.,Michejda, Christopher J.
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p. 442 - 445
(2007/10/02)
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- Reactions of cyclopropylcarbinol in dilute hydrochloric acid
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The treatment of cyclopropylcarbinol (1-OH) with dilute HCl has been used as a method for the preparation of cyclobutanol (2-OH).While 2-OH is the major product in this reaction, a careful investigation showed the presence of a total of 13 products, namely the alcohols 1-OH, 2-OH, and allylcarbinol (3-OH), cyclopropylcarbinyl, cyclobutyl and allylcarbinyl chlorides (1-Cl, 2-Cl and 3-Cl, respectively), dicyclopropylcarbinyl, cyclobutyl cyclopropylcarbinyl, allycarbinyl cyclopropylcarbinyl, dicyclobutyl and allylcarbinyl cyclobutyl ethers (1-O-1, 2-O-1, 3-O-1, 2-O-2, and 3-O-2, respectively), as well as butyraldehyde and isobutyraldehyde.The alcohols, chlorides, and ethers likely arose from reactions of the bicyclobutonium ion with available nucleophiles in the reaction mixture.The minor amounts of the two aldehydes may be due to a ring opening isomerization of 2-methylcyclopropanol, the latter in turn resulted from a net 1,3-hydride shift in the cyclopropylcarbinyl cation, probably via an edge-protonated cyclopropane-type of species.Treatment of cyclopropylcarbinol (1-OH-α-14C) with dilute HCl gave samples of 1-OH-x-14C, 2-OH-x-14C, and 3-OH-x-14C the degradation of which showed that all three methylene groups in these alcohols have become equivalent, indicating a complete equilibration between isotope-position labeled bicyclobutonium ions.
- Lee, Choi Chuck,Cessna, Allan J.
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p. 1075 - 1079
(2007/10/02)
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- Alkyltin cyclopropylcarbinylsulfonate
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Pesticidal and anti-inflammatory cyclopropyl compounds, cyclopropyl intermediates for the preparation of pesticidal compounds, especially chrysanthemic acid-like intermediates, and a process for preparing same.
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