- Nickel-catalyzed electrocarboxylation of allylic halides with CO2
-
Nickel-catalyzed regioselective electrocarboxylation of allylic halides with CO2at atmospheric pressure has been developed by adjusting reaction parameters, including catalyst, solvent, temperature and additive. β,γ-Unsaturated carboxylic acids were obtained in moderate to good yields and with high chain selectivity. This reaction shows tolerance to functional groups. In addition, cyclic voltammetry was performed to provide the possible mechanism of nickel-catalyzed CO2allylation.
- Wu, La-Xia,Deng, Fang-Jie,Wu, Lin,Wang, Huan,Chen, Tai-Jie,Guan, Ye-Bin,Lu, Jia-Xing
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p. 13137 - 13141
(2021/08/03)
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- Intramolecular Cyclization of Vinyldiazoacetates as a Versatile Route to Substituted Pyrazoles
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Vinyldiazo compounds undergo a thermal electrocyclization to form pyrazoles in yields of up to 95percent. The reactions are operationally simple, use readily available starting materials, require no intervention of a catalyst, and enable the synthesis of mono-, di- A nd tri-substituted pyrazoles. With the ability to produce highly substituted pyrazoles and the flexibility in installing various types of substituents, this method constitutes a new entry to this valuable heterocyclic scaffold and may be of interest to all branches of the chemical industry.
- Drikermann, Denis,G?rls, Helmar,Kerndl, Valerie,Vilotijevic, Ivan
-
supporting information
p. 1158 - 1162
(2020/07/20)
-
- Revisiting the Palladium-Catalyzed Carbonylation of Allyl Alcohol: Mechanistic Insight and Improved Catalytic Efficiency
-
Although crotonic acid (CA) is in high demand due to its use in various industrial applications, the preparation of CA currently requires a multi-step process from the petrochemical cracking of ethane with a very low overall yield and poor selectivity. An atom economical, one-step, carbonylation of readily accessible allyl alcohol to CA is one of the attractive approaches. In this study, the direct carbonylative transformation of allyl alcohol to CA was analyzed in detail to detect the reaction intermediates and propose a reaction mechanism. Following the reaction mechanism, the process was optimized to synthesize CA via the direct carbonylation of allyl alcohol with improved efficiency and productivity (TON = 420) under mild reaction conditions using Pd-based catalytic systems.
- Jiang, Jianwei,Padmanaban, Sudakar,Yoon, Sungho
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p. 1881 - 1886
(2020/06/10)
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- Silver encapsulated copper salen complex: Efficient catalyst for electrocarboxylation of cinnamyl chloride with CO2
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An active catalyst, [Cu]?Ag composite, was synthesized for the first time and used as a cathode for electrocarboxylation of cinnamyl chloride with CO2. β,γ-Unsaturated carboxylic acids were obtained with excellent yield and moderate selectivity. Moreover, reasonable yields and selectivities of carboxylic acids were also achieved with several allylic halides and aryl halides.
- Wu, La-Xia,Zhao, Ying-Guo,Guan, Ye-Bin,Wang, Hui,Lan, Yang-Chun,Wang, Huan,Lu, Jia-Xing
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p. 32628 - 32633
(2019/10/28)
-
- Combined high degree of carboxylation and electronic conduction in graphene acid sets new limits for metal free catalysis in alcohol oxidation
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Graphene oxide, the most prominent carbocatalyst for several oxidation reactions, has severe limitations due to the overstoichiometric amounts required to achieve practical conversions. Graphene acid, a well-defined graphene derivative selectively and homogeneously covered by carboxylic groups but maintaining the high electronic conductivity of pristine graphene, sets new activity limits in the selective and general oxidation of a large gamut of alcohols, even working at 5 wt% loading for at least 10 reaction cycles without any influence from metal impurities. According to experimental data and first principles calculations, the selective and dense functionalization with carboxyl groups, combined with excellent electron transfer properties, accounts for the unprecedented catalytic activity of this graphene derivative. Moreover, the controlled structure of graphene acid allows shedding light upon the critical steps of the reaction and regulating precisely its selectivity toward different oxidation products.
- Blanco, Matiás,Mosconi, Dario,Otyepka, Michal,Medve?, Miroslav,Bakandritsos, Aristides,Agnoli, Stefano,Granozzi, Gaetano
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p. 9438 - 9445
(2019/11/11)
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- Stereoselective Synthesis of Highly Substituted Tetrahydropyrans through an Evans Aldol-Prins Strategy
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A direct and general method for the synthesis of naturally occurring 2,3,4,5,6-pentasubstituted tetrahydropyrans has been developed, employing β,γ-unsaturated N-acyl oxazolidin-2-ones as key starting materials. The combination of the Evans aldol addition and the Prins cyclization allowed the diastereoselective and efficient generation of the desired oxacycles in two fashions: a one-pot Evans aldol-Prins protocol, in which five new σ bonds and five contiguous stereocenters were straightforwardly generated, and a two-step version, which additionally permitted the isolation of β,γ-unsaturated alcohol precursors bearing an N-acyl oxazolidin-2-one in the α position. From these alcohols were also obtained halogenated pentasubstituted tetrahydropyrans as well as 2,3,4,5-tetrasubstituted tetrahydrofurans, shedding light on the mechanism of the process. Computational studies were consistent with the experimental findings, and this innovative Evans aldol-Prins strategy was performed for the preparation of a battery of more than 30 densely substituted tetrahydropyrans, unprecedentedly fused to a 1,3-oxazinane-2,4-dione ring, both in a racemic fashion and in an enantiomeric fashion. These novel molecules were successfully submitted to several transformations to permit simple access to a variety of differently functionalized tetrahydropyrans. Most of these unique molecules were evaluated for their antimicrobial activity against Gram-positive and Gram-negative bacteria and the yeast Candida albicans, and some structure-activity relationships were established.
- álvarez-Méndez, Sergio J.,Fari?a-Ramos, Marta,Villalba, María Luisa,Perretti, Marcelle D.,García, Celina,Moujir, Laila M.,Ramírez, Miguel A.,Martín, Víctor S.
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p. 9039 - 9066
(2018/08/06)
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- Telescoped Synthesis of γ-Bromo-β-Lactones from Allylic Bromides Employing Carbon Dioxide
-
A direct synthesis of the title compounds involving a stepwise Zn-mediated carboxylation of allylic bromides with CO2 delivering β, γ-unsaturated carboxylic acids and a subsequent bromolactonization is reported. The described method demonstrates the use of readily prepared allylzinc bromides by the method of Knochel for fixation of CO2 employing commodity chemicals and zinc dust. This process was then optimized into a two-stage, telescoped process for the direct synthesis of γ-bromo-β-lactones from allyl bromides. The described strategy delivers functionalized β-lactones with dual reactivity as acylating and alkylating agents, which have utility as synthetic intermediates and are attracting growing interest as proteomic tools for activity-based protein profiling.
- Vellalath, Sreekumar,Romo, Daniel
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p. 335 - 339
(2017/04/13)
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- PROCESS FOR PREPARING MONO AND DICARBOXYLIC ACIDS
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The present application relates to a process for preparing a dicarboxylic acid or dicarboxylic ester according to general formula (IV) R1OOC-(CH2)m-CH2CH2-(CH2)y-COOR4 (IV), comprising the steps of subjecting alkenoic acid or alkenoate of formula (II) R1OOC-(CH2)m-CH=CH-(CH2)x-H (II) to a metathesis reaction in the presence of a metathesis catalyst to form a longer-chain alkenoic acid or alkenoate of formula (III) R1OOC-(CH2)m-CH=CH-(CH2)y-H (III) where xa carbonylation reaction in the presence of a carbonylation catalyst and a carbonyl source to form said compound of Formula (IV). Alternative embodiments provide: a process for preparing an alkenoic acid or alkenoate comprising the step of subjecting a lactone to a ring opening reaction; a process for preparing a monocarboxylic acid or monocarboxylic ester according to general formula (XI) R1OOC-(CH2)m-CH2-(CH2)y-CH3 (XI) by subjecting an alkenoic acid or alkenoate to alkene hydrogenation; and a process for preparing an alcohol or ether according to general formula (XII) R1O-CH2-(CH2)m-CH2-(CH2)y-CH3 (XII) by subjecting an alkenoic acid or alkenoate to hydrogenation. The use of the respective mono/dicarboxylic acid, mono/dicarboxylic ester, ethers or alcohols in a variety of applications is also disclosed.
- -
-
Page/Page column 33; 34
(2018/02/03)
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- Design of Core-Pd/Shell-Ag Nanocomposite Catalyst for Selective Semihydrogenation of Alkynes
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We designed core-Pd/shell-Ag nanocomposite catalyst (Pd@Ag) for highly selective semihydrogenation of alkynes. The construction of the core-shell nanocomposite enables a significant improvement in the low activity of Ag NPs for the selective semihydrogenation of alkynes because hydrogen is supplied from the core-Pd NPs to the shell-Ag NPs in a synergistic manner. Simultaneously, coating the core-Pd NPs with shell-Ag NPs results in efficient suppression of overhydrogenation of alkenes by the Pd NPs. This complementary action of core-Pd and shell-Ag provides high chemoselectivity toward a wide range of alkenes with high Z-selectivity under mild reaction conditions (room temperature and 1 atm H2). Moreover, Pd@Ag can be easily separated from the reaction mixture and is reusable without loss of catalytic activity or selectivity.
- Mitsudome, Takato,Urayama, Teppei,Yamazaki, Kenji,Maehara, Yosuke,Yamasaki, Jun,Gohara, Kazutoshi,Maeno, Zen,Mizugaki, Tomoo,Jitsukawa, Koichiro,Kaneda, Kiyotomi
-
supporting information
p. 666 - 670
(2016/02/18)
-
- Method for producing vinyl acetate, vinyl acetate and its manufacturing method deriv.
-
PROBLEM TO BE SOLVED: To provide a new vinyl acetic acid derivative, namely, to provide high-purity vinyl acetic acid and vinyl acetic acid derivatives having few isomers. SOLUTION: The 2-butene acid is mixed with water, converted into vinyl acetic acid highly selectively through isomerization by underwater photoreaction, and subjected to a solvent extraction/concentration step to obtain vinyl acetic acid, and thereafter induced into various vinyl acetic acid esters including new structures by an esterification reaction with an alcohol compound. COPYRIGHT: (C)2013,JPOandINPIT
- -
-
Paragraph 0084-0085
(2019/10/02)
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- Highly Regioselective Palladium-Catalyzed Carboxylation of Allylic Alcohols with CO2
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Various allylic alcohols were carboxylated in the presence of a catalytic amount of PdCl2 and PPh3 using ZnEt2 as a stoichiometric transmetalation agent under a CO2 atmosphere (1atm). This carboxylation proceeded in a highly regioselective manner to afford branched carboxylic acids predominantly. The β,γ-unsaturated carboxylic acid thus obtained was successfully converted into an optically active γ-butyrolactone, a known intermediate of (R)-baclofen.
- Mita, Tsuyoshi,Higuchi, Yuki,Sato, Yoshihiro
-
supporting information
p. 16391 - 16394
(2015/11/09)
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- Polymer supported rhodium carbonyl complex catalyzed carbonylation of glycerol for the synthesis of carboxylic acids
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A new polymer anchored Rh(I) complex has been synthesized and characterized. The catalytic performance of the complex has been tested for the carbonylation of glycerol under carbon monoxide atmosphere to give butyric and isobutyric acids. The effects of temperature, CO pressure, reaction time and the catalyst amount are reported. This catalyst showed excellent activity and recyclability being easily recovered by filtration and reused more than five times without appreciable loss of its initial activity.
- Molla, Rostam Ali,Ghosh, Kajari,Roy, Anupam Singha,Islam, Sk. Manirul
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p. 268 - 274
(2015/02/18)
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- A Strained Disilane-Promoted Carboxylation of Organic Halides with CO2 under Transition-Metal-Free Conditions
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By using a strained four-membered ring disilane (3,4-benzo-1,1,2,2-tetraethyldisilacyclobutene) and CsF, a wide range of aryl, alkenyl, alkynyl, benzyl, allyl, and alkyl halides was successfully carboxylated under an ambient CO2 atmosphere (CO2 balloon) at room temperature within 2 h. In this carboxylation, a highly reactive silyl anion, which is generated from the disilane and CsF, is a key to facilitating the formation of a carbanion equivalent. The resulting anionic species can be trapped with CO2 to produce carboxylic acids with high efficiency.
- Mita, Tsuyoshi,Suga, Kenta,Sato, Kaori,Sato, Yoshihiro
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supporting information
p. 5276 - 5279
(2015/11/18)
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- Direct carboxylation of allylic halides with carbon dioxide in the presence of indium
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A highly regioselective indium-mediated allylation of carbon dioxide starting from simple allylic halides (X = I, Br, Cl) has been developed. No transition metal catalyst is needed and an inert atmosphere is not necessary. The reaction tolerates a wide range of synthetically attractive functional groups with a very high branched regioselectivity. The Royal Society of Chemistry 2014.
- Miao, Bukeyan,Ma, Shengming
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supporting information
p. 3285 - 3287
(2014/03/21)
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- Polymer supported rhodium carbonyl complex catalyzed carbonylation of glycerol for the synthesis of carboxylic acids
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A new polymer anchored Rh(I) complex has been synthesized and characterized. The catalytic performance of the complex has been tested for the carbonylation of glycerol under carbon monoxide atmosphere to give butyric and isobutyric acids. The effects of temperature, CO pressure, reaction time and the catalyst amount are reported. This catalyst showed excellent activity and recyclability being easily recovered by filtration and reused more than five times without appreciable loss of its initial activity.
- Molla, Rostam Ali,Ghosh, Kajari,Roy, Anupam Singha,Islam, Sk. Manirul
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p. 268 - 274
(2015/02/18)
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- Regioselective copper-catalyzed carboxylation of allylboronates with carbon dioxide
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In the presence of a Cu(I)/NHC catalyst, the reactions of allylboronic pinacol esters with CO2 (1 atm) are highly regioselective, giving exclusively the more substituted β,γ-unsaturated carboxylic acids in most cases. A diverse array of substituted carboxylic acids can be prepared via this method, including compounds featuring all-carbon quaternary centers.
- Duong, Hung A.,Huleatt, Paul B.,Tan, Qian-Wen,Shuying, Eileen Lau
-
supporting information
p. 4034 - 4037
(2013/09/02)
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- Carbodeoxygenation of biomass: The carbonylation of glycerol and higher polyols to monocarboxylic acids
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Glycerol is converted to a mixture of butyric and isobutyric acid by rhodium- or iridium-catalysed carbonylation using HI as the co-catalyst. The initial reaction of glycerol with HI results in several intermediates that lead to isopropyl iodide, which upon carbonylation forms butyric and isobutyric acid. At low HI concentration, the intermediate allyl iodide undergoes carbonylation to give vinyl acetic acid and crotonic acid. Higher polyols CnH n+2(OH)n are carbonylated to the corresponding C n+1 mono-carboxylic acids. Copyright
- Coskun, Timur,Conifer, Christopher M.,Stevenson, Laura C.,Britovsek, George J. P.
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supporting information
p. 6840 - 6844
(2013/07/05)
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- Palladium catalyzed carboxylation of allylstannanes and boranes using CO2
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A family of well-defined (η3-allyl)Pd(L)(carboxylate) (L = PR3 or NHC) complexes are by far the most efficient catalysts reported to date for the catalytic carboxylation of allylstannanes into allylcarboxylates using CO2. The substrate scope of this reaction is extended to both substituted allylstannanes and allylboranes.
- Wu, Jianguo,Hazari, Nilay
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supporting information; experimental part
p. 1069 - 1071
(2011/02/25)
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- Electrocatalytic carboxylation of aliphatic halides at silver cathode in acetonitrile
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A simple and efficient electrocarboxylation reaction of aliphatic halides has been developed using silver as cathode, magnesium as anode and CH3CN saturated CO2 as solvent in an undivided cell. The influence of some key factors (such as the nature of electrode materials, supporting electrolytes and temperature) on this reaction was investigated. Under the optimized condition, the corresponding carboxylic acids were obtained in moderate to good yields (22-89%). The electrochemical behaviour was studied at different electrodes (Ag, Cu, Ni and Ti) by cyclic voltammetry, which showed significant electrocatalytic effect of the silver electrode towards the reductive carboxylation of aliphatic halides.
- Niu, Dong-Fang,Xiao, Li-Ping,Zhang, Ai-Jian,Zhang, Gui-Rong,Tan, Qi-Yun,Lu, Jia-Xing
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p. 10517 - 10520
(2008/12/23)
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- Enzymatic nitrile hydrolysis catalyzed by nitrilase ZmNIT2 from maize. An unprecedented β-hydroxy functionality enhanced amide formation
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To explore the synthetic potential of nitrilase ZmNIT2 from maize, the substrate specificity of this nitrilase was studied with a diverse collection of nitriles. The nitrilase ZmNIT2 showed high activity for all the tested nitriles except benzonitrile, producing both acids and amides. For the hydrolysis of aliphatic, aromatic nitriles, phenylacetonitrile derivatives and dinitriles, carboxylic acids were the major products. Unexpectedly, amides were found to be the major products in nitrilase ZmNIT2-catalyzed hydrolysis of β-hydroxy nitriles. The hydrogen bonding between the hydroxyl group and nitrogen in the enzyme-substrate complex intermediates that disfavors the loss of ammonia and formation of acyl-enzyme intermediate, which was further hydrolyzed to acid, was proposed to be responsible for the unprecedented β-hydroxy functionality assisted high yield of amide formation.
- Mukherjee, Chandrani,Zhu, Dunming,Biehl, Edward R.,Parmar, Rajiv R.,Hua, Ling
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p. 6150 - 6154
(2007/10/03)
-
- Exploring the synthetic applicability of a cyanobacterium nitrilase as catalyst for nitrile hydrolysis
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The substrate specificity and synthetic applicability of the nitrilase from cyanobacterium Synechocystis sp. strain PCC 6803 have been examined. This nitrilase catalyzed the hydrolysis of both aromatic and aliphatic nitriles to the corresponding acids in high yields. Furthermore, the stereoselective hydrolysis of phenyl-substituted β-hydroxy nitriles to (S)-enriched β-hydroxy carboxylic acids and selective hydrolysis of α,ω- dinitriles with five or less methylene groups to ω-cyano carboxylic acids have been achieved. This suggested that nitrilase from Synechocystis sp. PCC 6803 could be a useful enzyme catalyst for the "green" nitrile hydrolysis. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
- Mukherjee, Chandrani,Zhu, Dunming,Biehl, Edward R.,Hua, Ling
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p. 5238 - 5242
(2007/10/03)
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- Medium-dependent lithiated side products in the reductive lithiation of allylic phenyl thioethers. Diethyl ether versus tetrahydrofuran
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Diethyl ether is a convenient solvent for the reductive lithiation of allylic phenyl thioethers without the serious complications, which occur when the reaction is carried out in tetrahydrofuran.
- Screttas, Constantinos G.,Heropoulos, Georgios A.,Micha-Screttas, Maria,Steele, Barry R.
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p. 4357 - 4360
(2007/10/03)
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- Lewis acid-mediated carboxylation of aryl- and allylsilanes with carbon dioxide
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Aryl- and allylsilanes are carboxylated with CO2 with the aid of aluminum-based Lewis acids, to give aromatic and β, γ-unsaturated carboxylic acids in fair to good yields, respectively. Formation of the former is rationalized by an aromatic electrophilic substitution by CO2 activated by the Lewis acid, while the latter a nucleophilic addition of in situ-generated allylaluminum species to CO2.
- Hattori, Tetsutaro,Suzuki, Yutaka,Miyano, Sotaro
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p. 454 - 455
(2007/10/03)
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- Asymmetric photolysis of 2-phenylcycloalkanones with circularly polarized light: A kinetic model for magnetic field effects
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Magnetic field effects (MFE) on asymmetric photolysis involving a biradical intermediate have been investigated on a kinetic model where an intersystem crossing (ISC) of the intermediate is taken into account. Changes in the enantiomeric excesses (ee) of chiral substances with circularly polarized light (CPL) irradiation have been simulated, and the necessary conditions for observing the MFE were obtained. The asymmetric photolysis of racemic 2-phenylcycloalkanones (2-PCAs) with CPL has been carried out in both the presence and absence of a magnetic field. Since the anisotropy g factors of 2-PCAs are considerably large, the CPL-induced ee are achieved to a few percent after 90% decomposition though the MFE are not observed. The photolysis mechanism of 2-PCAs in an air-saturated solution has been also clarified. Triplet acyl-benzyl biradicals, formed via photochemical α-cleavage of 2-PCAs, react with O2 dissolved in the solution and result in the formation of acetophenone and alkenoic acids. The bimolecular reactions are diffusion-controlled and the rates are comparable to those of ISC to the singlet biradicals for all 2-PCAs. The recombination yields of the biradicals are sufficiently large. However, the biradical ISC rate shows little magnetic field dependence, which explains the absence of the MFE in this asymmetric photolysis.
- Kohtani, Shigeru,Sugiyama, Masahide,Fujiwara, Yoshihisa,Tanimoto, Yoshifumi,Nakagaki, Ryoichi
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p. 1223 - 1233
(2007/10/03)
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- Synthesis of 2,6-dideoxysugars via ring-closing olefinic metathesis.
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[formula: see text] Grubbs' RuCl2 (=CHPh)(PCy3)2 (catalyst 1) and RuCl2(=CHPh)(PCy3)(IMess) (catalyst 2) complexes have been successfully utilized in the construction of beta,gamma-unsaturated delta-lactones containing various substitution patterns of methyl groups. Asymmetric dihydroxylation followed by reduction leads to 3,4-cis-dihydroxy-2,6-dideoxypyranoses, which have proven to play very important biological roles as key components of natural products.
- Andreana, Peter R,McLellan, Jason S,Chen, Yongchen,Wang, Peng George
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p. 3875 - 3878
(2007/10/03)
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- Conjugate addition of organolithium reagents to α,β-unsaturated carbocyclic acids
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Conjugate addition of primary, secondary, tertiary alkyi and phenyl lithium reagents to 2-alkenoic acids affords good yields of branched saturated carboxylic acids. Methyl groups at the α- and β-carbon of the 2-alkenoic acid decrease reactivity as acceptors, and foster deprotonation, respectively. The lithium enediolate resulting from the conjugate addition can react with electrophiles. PM3 calculations are in agreement with the substituent effects.
- Aurell, Maria Jose,Domingo, Luis Ramon,Mestres, Ramon,Munos, Elena,Zaragoza, Ramon Jose
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p. 815 - 830
(2007/10/03)
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- An in-depth study of the biotransformation of nitriles into amides and/or acids using Rhodococcus rhodochrous AJ270
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A variety of aliphatic, aromatic and heterocyclic nitriles have been readily hydrolysed into the corresponding amides and/or acids under very mild conditions using Rhodococcus sp. AJ270. The nitrile hydratase involved in this novel nitrile-hydrolysing microorganism efficiently hydrates most nitriles tested, irrespective of the electronic and steric effects of the substituents, to form the amides. Conversion of amides into acids catalysed by the associated amidase is rapid and efficient in most cases. Substrates bearing an adjacent substituent (which may be an ortho substituent on an aromatic nitrile, an adjacent heteroatom in a heterocyclic ring or a geminal substituent in an α,β-unsaturated nitrile) undergo slow hydrolysis of the amides allowing efficient amide isolation. The scope, limitations and reaction mechanism of this enzymatic process have been systematically studied. A molecular size of >7 A diameter and the presence of functions capable of metal complexation near to the nitrile inhibit hydrolysis.
- Meth-Cohn, Otto,Wang, Mei-Xiang
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p. 1099 - 1104
(2007/10/03)
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- Activation of C-O and C-N Bonds in Allylic Alcohols and Amines by Palladium Complexes Promoted by CO2. Synthetic Applications to Allylation of Nucleophiles, Carbonylation, and Allylamine Disproportionation
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The direct activation of the C-O bonds in allylic alcohols catalyzed by palladium complexes has been accelerated by carrying out the reactions under CO2. On reaction with diethylamine, allyl alcohol can be converted into N,N-diethylallylamine in the presence of palladium complexes at room temperature under normal pressure of carbon dioxide. Allylation of various carbon nucleophiles such as β-keto esters and β-diketones can be achieved by using allylic alcohols directly in the presence of palladium complexes and CO2. Direct carbonylation of allylic alcohols into unsaturated carboxylic acids can be catalyzed by palladium complexes under the pressure of CO and CO2. Disproportionation of diallylamine into triallylamine and allylamine is also catalyzed by palladium complexes in the presence of CO2. On the basis of studies on the behavior of η3-allylpalladium hydrogencarbonate complexes with the nucleophiles, mechanisms are proposed to account for the palladium-catalyzed allylation processes influenced by CO2.
- Sakamoto, Masato,Shimizu, Isao,Yamamoto, Akio
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p. 1065 - 1078
(2007/10/03)
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- Palladium-Catalyzed Double and Single Carbonylation of Aryl Halides and Allylic Compounds
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After a brief introduction summarizing the author's previous work concerning the double carbonylation of aryl halides catalyzed by palladium complexes, newly found catalytic processes (1) for converting allylic formates and chlorides into β,γ-unsaturated acids and (2) the double carbonylation of allylic chlorides to β,γ-unsaturated α-keto amides are described.Mechanisms which reasonably account for the catalytic processes are proposed on the basis of studies concerning the properties of the organopalladium complexes.
- Yamamoto, Akio
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p. 433 - 446
(2007/10/02)
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- SEVERAL MECHANISMS IN THE ELIMINATION KINETICS OF ω-CHLOROCARBOXYLIC ACIDS IN THE GAS PHASE
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The kinetics of the gas-phase pyrolysis of ω-chlorocarboxylic acids were examined in a seasoned static reaction vessel and in the presence of at least twice the amount of the free radical inhibitor cyclohexene or toluene.In conformity with the available experimental data on rate determination, these reactions proved to be unimolecular and obeyed a first-order rate law.The presence of the primary chlorine leaving group in Cl(CH2)nCOOH (n=1-4) showed a change in mechanism from intramolecular displacement of the Cl leaving group by the acidic hydrogen of the COOH to anchimeric assistance of the carbonyl COOH to the C-Cl bond polarization in the transition state.This mechanistic consideration is nearly the same for the series of 2-, 3-, and 4-chlorobutyric acids.The chlorine atom at the 2-position of acetic, propionic and butyric acids is dehydrochlorinated through a prevailing reaction path involving a polar five-membered cyclic transition state.
- Chuchani, Gabriel,Martin, Ignacio,Rotinov, Alexandra,Dominguez, Rosa M.,Perez, Milogrados I.
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p. 133 - 138
(2007/10/02)
-
- Fluoroalkenyl compounds and their use as pest repellents
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Fluorinated alkene compounds useful for and methods of controlling nematodes, insects, and acarids that prey on agricultural crops. Polar compounds, for example, 3,4,4-trifluoro-3-butene-1-amine or 3,4,4-trifluoro-3-butenoic acid, are particularly useful for systemic control of pests. Novel method and intermediates for the preparation of 3,4,4-trifluoro-3-butene-1-amine are also provided.
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-
-
- Intramolecular Photochemical Cycloaddition Reactions of N-indoles and N-(ω-Alkenoyl)indoles
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Ultraviolet light irradiation of N-(but-3'-enoyl)indole (3i), N-(pent-4'-enoyl)indole (3j), and N-(hex-5'-enoyl)indole (3k) affords intramolecular photocycloadducts 17a-19a in which the termini of the side-chain alkene have become bonded to the 2- and 3-positions of the indole ring.The regiochemistry of the addition of the alkene is the opposite to that obtained in the corresponding intermolecular reaction of an N-acylindole with a monosubstituted alkene.The length of the methylene linkage between the tethered alkene and the N-acyl activating group in these N-alkenoylindoles affects the quantum efficiency of intramolecular cycloaddition as well as the ability of the reaction to compete with intermolecular cycloaddition in the presence of added cyclopentene.In contrast, the N-(ω-alkenyloxycarbonyl)indoles 3a-e are relatively photostable, apparently because they are frozen in an unreactive conformation for the duration of the excited state lifetime.Compounds 3a-e are, however, capable of undergoing intermolecular photocycloaddition in the presence of added alkenes and thay also photodimerize.These reaction pathways dominate when lower energy wavelengths (λ>300 nm) of ultraviolet light are used; irradiations performed at higher energy wavelength (254 nm) give predominantly photo-Fries rearrangement products.
- Oldroyd, David L.,Weedon, Alan C.
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p. 1333 - 1343
(2007/10/02)
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- Palladium-Catalyzed, Atmospheric Pressure Carbonylation of Allylic Halides under the Influence of Sodium Hydroxide or Alkoxides. A Facile Synthesis of β,γ-Unsaturated Acids
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The palladium-catalyzed, atmospheric-pressure carboxylation of allylic halides occurs readily in an aqueous sodium hydroxide/organic solvents two-phase system, giving β,γ-unsaturated acids.Phosphine complexes (I, L=m-(Ph2P)C6H4SO3Na; II, L=Ph3P) or Na2 (III) can be used as the catalyst.Atmospheric-pressure alkoxycarbonylation is realized under the influence of a homogeneous alcoholic solution of sodium alkoxide.Phosphine-free palladium complexes, such as 2 or III, are the favored catalyst. β,γ-Unsaturated esters are obtained in high yields.
- Okano, Tamon,Okabe, Nobuyuki,Kiji, Jitsuo
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p. 2589 - 2593
(2007/10/02)
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- Photolysis of the 1-naphthylmethyl ester of substituted phenylacetic acids: intramolecular charge transfer and rates of decarboxylation of arylacyl radicals
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The photolysis of esters 6 and 8 in methanol leads to products resulting from both naphthylmethyl cations and radicals.The product distribution is nearly independent of X for the esters 6 except when X equals methoxy.A mechanism involving initial homolytic cleavage of the carbon-oxygen bond in the excited singlet state of the ester is proposed.Competition between electron transfer in the radical pair to form the ion pair and decarboxylation of the arylacyloxy radical allows calculations of the rates of this decarboxylation process.The ρ values versus ? is close to zero.When X equals methoxy, intramolecular electron transfer occurs with the naphthalene ring serving as the acceptor and the methoxyaromatic as the donor.This exciplex fragments to carbon dioxide and 1-(1-naphthyl)-2-arylethane. Key words: acyloxy radical, decarboxylation, photolysis of benzylic esters.
- Hilborn, James W.,Pincock, James A.
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p. 992 - 999
(2007/10/02)
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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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- Palladium-Catalyzed, Atmospheric Pressure Carbonylation of Allylic Chlorides in Two-Phase Aqueous Sodium Hydroxide-Organic Solvent Media
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The palladium-catalyzed, atmospheric pressure carbonylation of allylic chlorides is realized in aqueous NaOH/benzene.Phosphine complexes PdCl2L2 (I) (a, L=Ph2P(m-C6H4SO3Na; b, L=Ph3P), or Na2PdCl4 can be used as the catalyst.
- Kiji, Jitsuo,Okano, Tamon,Nishiumi, Wataru,Konishi, Hisatoshi
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p. 957 - 960
(2007/10/02)
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- Main Group Conjugated Organic Anion Chemistry. 3. Application of Magnesium-Anthracene Compounds in the Synthesis of Grignard Reagents
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Reaction of magnesium-arene compounds, , 1, and some silylanthracene, and/or tertiary amine analogues, with benzylic and allylic chlorides or bromides, and (Me3Si)3CCl, afford Grignard reagents, RMgX, in modest to high yield for chlorides and negligible to high yield for the bromides, in THF, toluene, and hexane at -10 to 20 deg C.Novel benzylic-type Grignard reagents prepared in high yield include those of 9-(chloromethyl)anthracene, 2-(chloromethyl)pyridine and 8-(chloro(or bromo)methyl)quinoline, and poly-Grignard reagents derived from 1,8-bis(chloromethyl)naphthalene, 2,2'-bis(chloromethyl)-1,1'-binaphthyl, and 1,3,5,-tris(chloro(or bromo)methyl)benzene.Grignard reagent formation occurs via electron-transfer reactions.Aryl and alkyl halides yield mainly products derived from addition of the halide across the 9,10-positions of the anthracenes, via nucleophilic substitution or collapse of a diradical cage 2+, (anthracene)-anion radical, RX-anion radical.>
- Harvey, Stephen,Junk, Peter C.,Raston, Colin L.,Salem, Geoffrey
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p. 3134 - 3140
(2007/10/02)
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- Ether cleavage by activated metals II.* Cleavage of allyl and benzyl ethers by activated magnesium
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Activated magnesium (prepared by reduction of magnesium halides with potassium) reacts with allyl and benzyl ethers to give the corresponding allyl or benzyl magnesium compounds.
- Bartmann, Ekkehard
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- SUR LA REGIO SELECTIVITE DE LA REACTION DU BENZALDEHYDE AVEC LES ORGANOZINQUES ISSUS DU γ-BROMOCROTONATE ET DU γ-BROMOSENECIOATE DE TRIMETHYLSILYLE
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The regioselectivity of the reaction of organozinc compounds derived from γ-bromocrotonic and γ-bromosenecioic trimethylsilyl esters, with benzaldehyde is discussed.One-step reactions lead to a majority of α-substituted derivatives, while in two-step reactions, γ-substituted products are exclusively obtained.
- Bellassoued, M.,Gaudemar, M.,Borgi, A. El.,Baccar, B.
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p. 165 - 172
(2007/10/02)
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- Carbanions. 23. Cleavage of 1,2-Diphenylethane and Derivatives by Cs-K-Na Alloy. Cometitive Rates of Bond Scission
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The following hydrocarbons are cleaved at a C-C bond to allylic and or/benzylic cesium compounds within 2 h by Cs-K-Na alloy in THF at -75 deg C: meso-2,3-diphenylbutane, 2,3-dimethyl-2,3-diphenylbutane, 1,2,2-triphenylpropane, 4-phenyl-1-butene, bibenzyl, and eight o-,m-, or p-methyl derivatives of bibenzyl.Under the same conditions 2-methyl- and 3-methyl-4-phenyl-1-butene were partially cleaved, 4,4'-dimethylbibenzyl was only slightly cleaved, and 9,10-dihydrophenanthrene was not detectably cleaved, while 10,11-dihydro-5H-dibenzocycloheptene underwent alternative C-H bond cleavage.Under the present reaction conditions 4,4'-dimethylbibenzyl and 9,10-dihydrophenanthrene were converted largely to dianions.It is suggested that all of the compounds undergoing cleavage are converted to dianions prior to cleavage.From competitive experiments the rates of reductive cleavage of most of these hydrocarbons relative to bibenzyl have been measured at -75 deg C.The relative rates of cleavage of m- and p-methylderivatives of bibenzyl may be correlated with the relative equilibrium acidities of toluene, m-xylene, and p-xylene in a modified Hammett relationship.Cleavages of benzylic C-C bonds are believed to occur by way of a preferred transition-state geometry,7, which permits the ?* orbital of the bond undergoing cleavage to interact with the HOMO's of both aromatic rings.Compounds that cannot attain this transition-state geometry are cleaved slowly if at all.The variable effect upon reaction rate of methyl groups near the bond undergoing cleavage are discussed in terms of ground-state and transition-state atrain, solvation, and polarizability of methyl groups.According to labeling experiments (o-methylbenzyl)cesium undergoes ready intramolecular sigmatropic migration of hydrogen from the methyl group to the methylene group when warmed from -75 deg C to near room temperature.
- Grovenstein, Erling,Bhatti, Amjad M.,Quest, Dean E.,Sengupta, Dibyendu,VanDerveer, Don
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p. 6290 - 6299
(2007/10/02)
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- Studies on Ketene and Its Derivatives. CXVIII. Nickel- or Palladium-Catalyzed Reaction of Diketene with Organometallics. Synthesis of 3-Substituted 3-Butenoic Acids
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The reaction of diketene (1) with some organometallics was investigated.The reaction of 1 with benzyl Grignard reagents in the presence of nickel(II) chloride afforded 3-benzyl-3-butenoic acids 2a-e.In the presence of dichloronickel, primary alkylmagnesium bromides reacted with 1 to give 3-methylenealkanoic acids 2g-i. (E)-1-Alkenyldiisobutylaluminiums, in the presence of Pd(O)-catalyst, reacted with 1 to give 3-methylene-4-alkenoic acids 5a-c.Similarly, alkynyl- and aryl-zinc chlorides gave 3-methylene-4-alkynoic acids 7a-d and 3-aryl-3-butenoic acids 8a-c, respectively.Keywords - diketene: Grignard reagent; alkenylaluminium; alkynylzinc chloride; arylzinc chloride; palladium-catalyst; nickel-catalyst; 3-butenoic acid; 3-substituted 3-butenoic acid
- Abe, Yoshihito,Sato, Masayuki,Goto, Hiroyuki,Sugawara, Rie,Takahashi, Eri,Kato, Tetsuzo
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p. 4346 - 4354
(2007/10/02)
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- STUDIES ON KETENE AND ITS DERIVATIVES. CXV. REACTION OF DIKETENE WITH ORGANOMETALLICS IN THE PRESENCE OF THE NICKEL- OR PALLADIUM PHOSPHINE COMPLEX
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Reaction of diketene (1) with alkyl, alkenyl, alkynyl, and aryl organometallics proceeded under catalysis of nickel(Ni)- or palladium(Pd)-phosphine complex to give 3-substitued 3-butenoic acids (2a-k).
- Abe, Yoshihito,Goto, Hiroyuki,Sato, Masayuki,Kato, Tetsuzo
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p. 1108 - 1111
(2007/10/02)
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- EFFICIENT PREPARATION OF ALLYLIC GRIGNARD REAGENTS USING SLURRIES OF PRECONDENSED MAGNESIUM
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Using a simple apparatus addition of 2-alkenyl halides to precondensed active Mg in THF gave clean solutions of 2-alkenylmagnesium halides which on carbonation furnished β,γ-unsaturated carboxylic acid in high yields.
- Oppolzer, Wolfgang,Kuendig, Ernest Peter,Bishop, Paul M.,Perret, Celia
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p. 3901 - 3904
(2007/10/02)
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- REACTIONS OF BENZYNE WITH SULFIDES HAVING A CARBOXYL GROUP. A NOVEL SYNTHESIS OF ESTER AND LACTONE
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Reactions of benzyne with o- and p-(alkylthio)benzoic acids afford alkyl o- and p-(phenylthio)benzoates in varied yields, while reaction with o-(phenylthio)methylbenzoic acid gives phtalide and diphenyl sulfide in good yields.
- Nakayama, Juzo,Fujita, Toko,Hoshino, Masamatsu
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p. 1777 - 1780
(2007/10/02)
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- Studies in Decarboxylation. Part 14. The Gas-phase Decarboxylation of But-3-enoic Acid and the Intermediacy of Isocrotonic (cis-But-2-enoic) Acid in its Isomerisation to Crotonic (trans-But-2-enoic) Acid
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At 593 K the complex system (A) is shown to be rapidly set up starting from any of the pure acids.Of particular crotonic acid isocrotonic acid but-3-enoic acid propene + CO2 (A) interest is the intermediacy of isocrotonic acid (the thermodynamically least stable of the three) in the interconversion of crotonic and but-3-enoic acids.A mechanism involving the enolic form of a carboxylic acid is proposed to account for this feature.The interconversion of crotonic and isocrotonic acids is much more rapid than that of their ethyl esters and a basis is proposed for the difference.Activation parameters relating to the decarboxylation of but-3-enoic acid are isolated by the flow technique.
- Bigley, David B.,Clarke, Michael J.
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- Titanium-promoted Allyl Transfer to Carbon Monoxide and Other Unsaturated Molecules
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Carbonylation of Cp2Ti-(?-allyl) yields Cp2Ti(CO)2 and triallylmethanol; reactions of Cp2Ti-(?-allyl) and Cp2Ti-(?-1-methylallyl) with other ligands proceed via insertion or allyl-elimination pathways.
- Klei, Bert,Teuben, Jan H.,Meijer, Henk J. de Liefde
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p. 342 - 344
(2007/10/02)
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- Carboxylic acid preparation
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A process for preparing 3-butenoic acid which comprises contacting allyl alcohol with carbon monoxide and a palladium chloride catalyst at a temperature between about 50° and 300° C. and under superatmospheric pressure and wherein the reaction is carried out in a substantially anhydrous C2 -C10 carboxylic acid liquid solvent. Preferably the solvent is acetic acid.
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- Process for the manufacture of vinyl acetic acid and optionally of γ-b
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Vinylacetic acid and optionally γ-butyrolactone are prepared by reacting an allyl compound substituted by oxygen functions with carbon monoxide in the presence of a heavy metal catalyst. When the reaction is carried out with an allyl ether or a carboxylic acid allyl ester water is added. Vinylacetic acid is obtained in a very good yield in simple and economic manner.
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