- Acetyl nitrate mediated conversion of methyl ketones to diverse carboxylic acid derivatives
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The development of a novel acetyl nitrate mediated oxidative conversion of methyl ketones to carboxylic acid derivatives is described. By analogy to the haloform reaction and supported by experimental and computational investigation we propose a mechanism for this transformation.
- Bernard, Josephine,Capilato, Joseph N.,Hoy, Erik P.,Mattiucci, Joseph,Pellegrinelli, Peter J.,Perez, Lark J.,Philippi, Shane,Schnorbus, Logan
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p. 5298 - 5302
(2021/06/30)
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- Mechanically induced solvent-free esterification method at room temperature
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Herein, we describe two novel strategies for the synthesis of esters, as achieved under high-speed ball-milling (HSBM) conditions at room temperature. In the presence of I2 and KH2PO2, the reactions afford the desired esterification derivatives in 45% to 91% yields within 20 min of grinding. Meanwhile, using KI and P(OEt)3, esterification products can be obtained in 24% to 85% yields after 60 min of grinding. In addition, the I2/KH2PO2 protocol was successfully extended to the late-stage diversification of natural products showing the robustness of this useful approach. Further application of this method in the synthesis of inositol nicotinate was also discussed. This journal is
- Zheng, Lei,Sun, Chen,Xu, Wenhao,Dushkin, Alexandr V.,Polyakov, Nikolay,Su, Weike,Yu, Jingbo
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p. 5080 - 5085
(2021/02/05)
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- Conversion of esters to thioesters under mild conditions
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We report conversion of esters to thioestersviaselective C-O bond cleavage/weak C-S bond formation under transition-metal-free conditions. The method is notable for a general and practical transition-metal-free system, broad substrate scope and excellent functional group tolerance. The strategy was successfully deployed in late-stage thioesterification, site-selective cross-coupling/thioesterification/decarbonylation and easy-to-handle gram scale thioesterification. Selectivity and computational studies were performed to gain insight into the formation of weak C-S bonds by C-O bond cleavage, which contrasts with the traditional trend of nucleophilic additions to carboxylic acid derivatives.
- Shi, Yijun,Liu, Xuejing,Cao, Han,Bie, Fusheng,Han, Ying,Yan, Peng,Szostak, Roman,Szostak, Michal,Liu, Chengwei
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supporting information
p. 2991 - 2996
(2021/04/14)
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- An alternative route for boron phenoxide preparation from arylboronic acid and its application for C[sbnd]O bond formation
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An efficient synthetic route to benzyl phenyl ether preparation has been successfully developed via a one-pot synthetic protocol utilizing a combination of arylboronic acids, hydrogen peroxide (H2O2), and benzyl halides. The whole procedure consists of two consecutive reactions, formation of boron phenoxide from arylboronic acids and its nucleophilic attack. A simple operation under mild conditions such as room-temperature ionic liquid (choline hydroxide), aerobic environment, and absence of metal- and base-catalysts has been employed. Expansion to utilize benzyl surrogates was also successfully accomplished.
- Joo, Seong-Ryu,Kim, Seung-Hoi,Lim, In-Kyun
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- Palladium-catalyzed aryloxy- and alkoxycarbonylation of aromatic iodides in γ-valerolactone as bio-based solvent
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Fossil-based solvents and triethylamine as a toxic and volatile base were successfully replaced with γ-valerolactone as a non-volatile solvent and K2CO3 as inorganic base in the alkoxy- and aryloxycarbonylation of aryl iodides using phosphine-free Pd catalyst systems. By this, the traditional systems were not simply replaced but also significantly improved. In the study, the effects of different reaction parameters, i.e. the use of several other solvents, the temperature, the carbon monoxide pressure, the base and the catalyst concentrations, were evaluated in details on the efficiency of the carbonylations. To gather some information on the mechanism of these reactions, the effects of the electronic parameters (σ) of various aromatic substituents of the aryl iodides as well as the influence of para-substitution of phenol were investigated on the activity. For a comparison, the aryl-substituted aryl iodides were also reacted with methanol and aryl iodide was also alkoxycarbonylated using several different lower alcohols. From the observed correlations between the electronic parameters of the aromatic substituents and the rates, it appears that the rate determining step is the oxidative addition of Ar–I to Pd0, provided that sufficient amounts of nucleophiles are present for the ester formation. If this is not the case, the rate of nucleophile attack might determine the overall rate.
- Tukacs, József M.,Marton, Bálint,Albert, Eszter,Tóth, Imre,Mika, László T.
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- Method for preparing diaryl ester compound through efficient catalysis of pyridine palladium
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The invention discloses a method for preparing a diaryl ester compound through efficient catalysis of pyridine palladium. The method is used for high-efficiency high-yield preparation of the diaryl ester compound under mild conditions by taking a phenol compound, an iodobenzene compound and carbon monoxide as raw materials, triethylamine as alkali and pyridine palladium as a catalyst. The method provided by the invention has the advantages of less usage amount of the palladium catalyst, high catalytic activity of the palladium catalyst, stability of the palladium catalyst to air, simple operation, short reaction time and high atom economy, opens up a low-cost, green and efficient way for preparation of diaryl ester compounds, and has broad application prospects.
- -
-
Paragraph 0016-0020; 0046-0050
(2020/12/31)
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- Cu(II)-silsesquioxanes as efficient precatalysts for Chan-Evans-Lam coupling
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Two cage copper(II)silsesquioxanes, namely, tricopper complex (PhSiO1.5)8(CuO)3(TMEDA)2*(MeCN)3 Cu-1 and hexacopper complex (MeSiO1,5)12(CuO)6(Py)6*TMEDA Cu
- Astakhov, G. S.,Bantreil, X.,Bilyachenko, A. N.,Dorovatovskii, P. V.,Khrustalev, V. N.,Lamaty, F.,Levitsky, M. M.,Shubina, E. S.,Zubavichus, Y. V.
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- Design and Bioevaluation of Novel Hydrazide-Hydrazones Derived from 4-Acetyl-N-Substituted Benzenesulfonamide
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Abstract: In this research, a series of hydrazine-hydrazone derivatives (Ia–g), (IIa–h) were synthesized to discover new antioxidant and anticholinesterase agents. The structures of synthesized compounds were characterized by spectroscopic data using UV, IR, 1H, 13C NMR, mass spectroscopy, and elemental analysis. The bio-evaluation of the synthesized compounds (Ia–g), (IIa–h) were evaluated according to in vitro activity assays. The results of β-carotene/linoleic acid assay showed that among the synthesized compounds, the (Ib), (Ie), (IIb–IIe), and (IIh) compound exhibited higher activity for the lipid peroxidation inhibitory activity. In the DPPH free scavenging activity and the cation radical scavenging activity in ABTS?+ activity, compound (IIb) was found to be more active. In the CUPRAC reduced power assay, the A0.5 values of all synthesized compounds were better than α-TOC. In AChE assay, compound (IIb) exhibited the most activity with IC50 = 11.12 ± 0.74 μM, while the compounds (Ib–g) and (IIb–h), exhibited excellent activity than the positive standard galantamine (IC50 = 46.06 ± 0.10 μM) in the BChE assay.
- ?ztürk, M.,Bozkurt, E.,Iyido?an, A. Karakü?ük,Oru?-Emre, E. E.,S?cak, Y.
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p. 702 - 714
(2020/10/29)
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- Amidation and esterification of carboxylic acids with amines and phenols by N,N′-diisopropylcarbodiimide: A new approach for amide and ester bond formation in water
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The present study reports the successful synthesis of two important and abundant functional groups “ester and amide” by N,N′-diisopropylcarbodiimide (DIC) in water as a green solvent. A wide range of substrates could be employed with high functional group tolerance. The products were obtained in high yields after short reaction times. This method provides an efficient, economic, simple and very mild protocol for ester and amide bond formation in aqueous media. In addition, this work not only may lead to environmentally benign systems but also will provide a new aspect of organic chemistry in water.
- Fattahi, Nadia,Ayubi, Morteza,Ramazani, Ali
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p. 4351 - 4356
(2018/07/13)
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- Rhodium-catalysed aryloxycarbonylation of iodo-aromatics by 4-substituted phenols with carbon monoxide or paraformaldehyde
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Rhodium-catalysed phenoxycarbonylation of aryl iodides were carried out under carbon-monoxide atmosphere and in the absence of CO, using paraformaldehyde as an alternative surrogate for carbonylation reactions. Both strategies proved to be efficient for the synthesis of the corresponding phenyl esters. High pressure reactions provided the ester products with good selectivity, however lower activity was achieved compared to palladium containing systems. Using paraformaldehyde as carbon-monoxide source special reaction conditions are required, thus dramatic changes observed during optimisation reactions. Using in situ generated Rh-diphosphine catalyst systems, remarkable influence of ligand structure and solvent composition was observed on the activity and chemoselectivity. The substrate scope and the substituent effect were also investigated.
- Seni, Anas Abu,Kollár, László,Mika, László T.,Pongrácz, Péter
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- Palladium-Catalyzed Oxidative Carbonylation of Aryl Hydrazines with CO and O2 at Atmospheric Pressure
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Palladium-catalyzed aerobic oxidative aminocarbonylation and alkoxycarbonylation reactions with aryl hydrazines as coupling partners have been developed. The oxidative carbonylation of aryl hydrazines proceeded smoothly at atmospheric pressure CO, employi
- Tu, Yongliang,Yuan, Lin,Wang, Tao,Wang, Changliu,Ke, Jiamei,Zhao, Junfeng
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p. 4970 - 4976
(2017/05/12)
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- Crystal engineering of hand-twisted helical crystals
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A strategy is outlined for the design of hand-twisted helical crystals. The starting point in the exercise is the one-dimensional (1D) plastic crystal, 1,4-dibromobenzene, which is then changed to a 1D elastic crystal, exemplified by 4-bromophenyl 4'-chlorobenzoate, by introduction of a molecular synthon -O-CO-in lieu of the supramolecular synthon Br···Br in the precursor. The 1D elastic crystals are next modified to two-dimensional (2D) elastic crystals, of the type 4-bromophenyl 4'-nitrobenzoate where the halogen bonding and C-H· · ·O hydrogen bonding are well-matched. Finally, varying the interaction strengths in these 2D elastic crystals gives plastic crystals with two pairs of bendable faces but without slip planes. Typical examples are 4-chlorophenyl and 4-bromophenyl 4'-nitrobenzoate. This type of 2D plasticity represents a new type of bendable crystals in which plastic behavior is seen with a fair degree of isotropic character in the crystal packing. The presence of two sets of bendable faces, generally orthogonal to each other, allows for the possibility of hand-twisting of the crystals to give grossly helical morphologies. Accordingly, we propose the name hand-twisted helical crystals for these substances.
- Saha, Subhankar,Desiraju, Gautam R.
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p. 1975 - 1983
(2017/02/15)
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- Sodium cyanide-promoted copper-catalysed aerobic oxidative synthesis of esters from aldehydes
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A simple and efficient copper-catalysed procedure for oxidative esterification of aldehydes with alcohols and phenols mediated by sodium cyanide, using air as a clean oxidant, is described. A variety of aromatic aldehydes and structurally different alcohols and phenols reacted efficiently, and the product esters were obtained in good to excellent yields under normal atmospheric and solvent-free conditions.
- Nowrouzi, Najmeh,Abbasi, Mohammad,Bagheri, Maryam
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- Transition-Metal-Free Poly(thiazolium) Iodide/1,8-Diazabicyclo[5.4.0]undec-7-ene/Phenazine-Catalyzed Esterification of Aldehydes with Alcohols
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Poly(3,4-dimethyl-5-vinylthiazolium) iodide was used as a polymer precatalyst in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and phenazine for the oxidative esterification of aldehydes with alcohols. Selective functionalization of OH groups was achieved in the presence of NH2 groups. The poly(thiazolium) iodide/DBU/phenazine system exhibited excellent catalytic activity and could be reused five times without loss of activity.
- Chun, Supill,Chung, Young Keun
-
supporting information
p. 3787 - 3790
(2017/07/26)
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- Palladium-catalyzed non-directed C[sbnd]H benzoxylation of simple arenes with iodobenzene dibenzoates
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A palladium-catalyzed non-directed C[sbnd]H benzoxylation of simple arenes with iodobenzene dibenzoates as both benzoxylate source and oxidant has been developed. The catalytic system was greatly promoted by a pyridine ligand. Good functional groups tolerance was showed in both hypervalent iodine reagents and arene substrates, which can be used for synthesis of aryl benzoates through simple aromatic compounds.
- Li, Li,Wang, Ying,Yang, Tingting,Zhang, Qian,Li, Dong
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supporting information
p. 5859 - 5863
(2016/12/09)
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- Thiophosphoramides as cooperative catalysts for copper-catalyzed arylation of carboxylates with diaryliodonium salts
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A thiophosphoramide-based co-catalyst was found to significantly accelerate copper(ii) trifluoromethanesulfonate-catalyzed arylation of potassium carboxylates with diaryliodonium salts. This effect could be attributed to counterion activation of diaryliodonium salts or organocopper intermediates by thiophosphoramides. Inclusion of thiophosphoramides permits achieving significantly milder reaction conditions and expands the scope of solvents and diaryliodonium counterions that could be used for the arylation of carboxylate nucleophiles.
- Bhattarai, Bijay,Tay, Jia-Hui,Nagorny, Pavel
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supporting information
p. 5398 - 5401
(2015/03/30)
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- Erbium trifluoromethanesulfonate catalyzed Friedel-Crafts acylation using aromatic carboxylic acids as acylating agents under monomode-microwave irradiation
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Erbium trifluoromethanesulfonate is found to be a good catalyst for the Friedel-Crafts acylation of arenes containing electron-donating substituents using aromatic carboxylic acids as the acylating agents under microwave irradiation. An effective, rapid and waste-free method allows the preparation of a wide range of aryl ketones in good yields and in short reaction times with minimum amounts of waste.
- Tran, Phuong Hoang,Hansen, Poul Erik,Nguyen, Hai Truong,Le, Thach Ngoc
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p. 612 - 618
(2015/02/19)
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- Ligand-free palladium-catalyzed aerobic oxidative coupling of carboxylic anhydrides with arylboronic acids
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We report a new, effective and environmentally friendly protocol for selective aerobic oxidative coupling of arylboronic acids with carboxylic anhydrides in the presence of ligand-free palladium catalyst. The aryl benzoates are obtained in good to excellent yields.
- Yin, Weiyan,He, Haifeng,Zhang, Yani,Long, Tong
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p. 2402 - 2406
(2014/10/15)
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- Direct esterification of aromatic aldehydes with tetraphenylphosphonium bromide under oxidative N-heterocyclic carbene catalysis
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An unconventional reagent, tetraphenylphosphonium bromide, was employed as a phenyl source in the direct transformation of aromatic aldehydes to the corresponding phenyl esters under oxidative N-heterocyclic carbene (NHC) catalysis. The phenyl esters were obtained in moderate yields under mild and organocatalytic conditions. Copyright
- Ramanjaneyulu, Bandaru T.,Pareek, Manish,Reddy, Virsinha,Vijaya Anand
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p. 431 - 437
(2014/04/03)
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- N-Heterocyclic carbene catalysed aerobic oxidation of aromatic aldehydes to aryl esters using boronic acids
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The organocatalytic behavior of N-heterocyclic carbenes in the aerobic oxidation of aromatic aldehydes to esters with boronic acids has been explored. This transition metal-free protocol allows access to a wide variety of aromatic esters in good to excellent yields under mild reaction conditions.
- Arde, Panjab,Ramanjaneyulu,Reddy, Virsinha,Saxena, Apurv,Anand, R. Vijaya
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supporting information; experimental part
p. 848 - 851
(2012/02/05)
-
- Preparation of benzoyloxy benzophenone derivatives and their inhibitory effects of ICAM-1 expression
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Benzoyloxy benzophenone derivatives were prepared in 3 steps including DCC coupling, Fries rearrangement and esterification from benzoic acids in 24-89% total yields. Among the prepared 12 benzophenone analogues 1a-1l, the compound 1b having three chloro groups at the para position showed maximum inhibitory effects of ICAM-1 expression but, 1a which have no substituents at all showed no inhibitory activity. This study provides the evidences that benzoyloxy benzophenone derivative, 1b may exert its anti-inflammatory activity by suppressing IFN-γ-induced ICAM-1 expression.
- Kwon, Eun Mi,Kim, Cheol Gi,Goh, Ah Ra,Park, Jinseu,Jun, Jong-Gab
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experimental part
p. 1939 - 1944
(2012/08/07)
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- NHC/Iron cooperative catalysis: Aerobic oxidative esterification of aldehydes with phenols
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An NHC/iron cooperative catalytic system mediates the aerobic oxidative esterification of aldehydes with phenols. The use of equimolar amounts of reactants led to good to excellent isolated yields of esters.
- Reddy, R. Sudarshan,Rosa, Joao N.,Veiros, Luis F.,Caddick, Stephen,Gois, Pedro M. P.
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supporting information; experimental part
p. 3126 - 3129
(2011/05/12)
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- Radical OfC transposition: A metal-free process for conversion of phenols into benzoates and benzamides
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We report a metal-free procedure for transformation of phenols into esters and amides of benzoic acids via a new radical cascade. Diaryl thiocarbonates and thiocarbamates, available in a single high-yielding step from phenols, selectively add silyl radicals at the sulfur atom of the CdS moiety. This addition step, analogous to the first step of the Barton-McCombie reaction, produces a carbon radical which undergoes 1,2 OfC transposition through an O-neophyl rearrangement. The usually unfavorable equilibrium in the reversible rearrangement step is shifted forward via a highly exothermic C-S bond scission in the O-centered radical, which furnishes the final benzoic ester or benzamide product. The metal-free preparation of benzoic acid derivatives from phenols provides a potentially useful alternative to metal-catalyzed carbonylation of aryl triflates.
- Baroudi, Abdulkader,Alicea, Jeremiah,Flack, Phillip,Kirincich, Jason,Alabugin, Igor V.
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experimental part
p. 1521 - 1537
(2011/06/11)
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- Molybdenum hexacarbonyl mediated alkoxycarbonylation of aryl halides
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Mo(CO)mediates the alkoxycarbonylation of aryl halides in their reaction with alcohols to afford arenecarboxylic acid esters. The molybdenum carbonyl complexes act as the catalyst and the source with carbon monoxide. The alkoxycarbonylation proceeds with a small excess of carbon monoxide in the form of Mo(CO)and the procedure is simple compared to the conventional method, which uses palladium catalyst under gaseous carbon monoxide. Using this procedure, a variety of carboxylic acid esters were prepared. Georg Thieme Verlag Stuttgart ? New York.
- Ren, Wei,Emi,Yamane, Motoki
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experimental part
p. 2303 - 2309
(2011/09/19)
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- NHC-iron-catalyzed aerobic oxidative aromatic esterification of aldehydes using boronic acids
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(Figure presented) NHC-iron complexes prepared in situ very efficiently afforded benzoates via the aerobic oxidative aromatic esterification of aldehydes with boronic acids. This method uses equimolar amounts of both the aldehyde and the boronic acid allo
- Rosa, Joao N.,Reddy, R. Sudarshan,Candeias, Nuno R.,Cal, Pedro M. S. D.,Gois, Pedro M. P.
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supporting information; experimental part
p. 2686 - 2689
(2010/09/03)
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- Radical 1,2-o→c transposition for conversion of phenols into benzoates by o-neophyl rearrangement/fragmentation cascade
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Figure Presented Radical merry-go-round! Diaryl thiocarbonates, available in a single step from phenols, can be directly transformed into benzoates by a new radical cascade that transposes O and C atoms at the aromatic core. The cascade bypasses the common Barton McCombie fragmentation in favor of the usually unfavorable O-neophyl rearrangement, which is rendered irreversible and efficient by a highly exothermic C-S bond scission in the O-centered radical (see scheme; FG = functional group).
- Baroudi, Abdulkader,Alicea, Jeremiah,Alabugin, Igor Y.
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experimental part
p. 7683 - 7687
(2010/08/22)
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- Copper(II)-catalyzed esterification of arenecarboxylic acids with aryl- and vinyl-substituted trimethoxysilanes
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In this paper, the copper(II)-catalyzed esterification reaction of arenecarboxylic acids with aryl- or vinyl-substituted trimethoxysilanes is described. A series of aryltrimethoxysilanes and arenecarboxylic acids worked well under this procedure, affording aryl benzoate derivatives in moderate to good yields. Notably, trimethoxy(vinyl)silanes also worked well under this procedure giving a facile and versatile method to access vinyl benzoate derivatives. Georg Thieme Verlag Stuttgart.
- Luo, Fang,Pan, Changduo,Qian, Pengcheng,Cheng, Jiang
-
supporting information; experimental part
p. 2005 - 2010
(2010/08/19)
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- Cu(OTf)2-mediated Chan-Lam reaction of carboxylic acids to access phenolic esters
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A Cu(OTf)2-mediated Chan-Lam reaction of carboxylic acids with arylboronic acids is described. It represents a facile and practical methodology to access phenolic esters in moderate to good yields. The procedure tolerates a series of functional groups, such as methoxycarbonyl, acetoxy, free phenolic hydroxyl, vinyl, nitro, trifluoromethyl, methoxyl, bromo, chloro, iodo, and acetyl groups.
- Zhang, Lingli,Zhang, Guoying,Zhang, Manli,Cheng, Jiang
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experimental part
p. 7472 - 7474
(2011/01/03)
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- Synthesis and biological evaluation of 4′-(6,7-disubstituted-2,4-dihydro-indeno[1,2-c]pyrazol-3-yl)-biphenyl-4-ol as potent Chk1 inhibitors
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A new series of potent tricyclic pyrazole-based Chk1 inhibitors are described. Analogues disubstituted on the 6- and 7-positions show improved Chk1 inhibition potency compared with analogues with a single substituent on either the 6- or 7-position. Based
- Tao, Zhi-Fu,Li, Gaoquan,Tong, Yunsong,Chen, Zehan,Merta, Philip,Kovar, Peter,Zhang, Haiying,Rosenberg, Saul H.,Sham, Hing L.,Sowin, Thomas J.,Lin, Nan-Horng
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p. 4308 - 4315
(2008/02/09)
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- TRICYCLIC PYRAZOLE KINASE INHIBITORS
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Compounds of the present invention are useful for inhibiting protein tyrosine kinases. Also disclosed are methods of making the compounds, compositions containing the compounds, and methods of treatment using the compounds.
- -
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Page/Page column 78
(2008/06/13)
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- Efficient method for the preparation of inverted alkyl carboxylates and phenyl carboxylates via oxidation-reduction condensation using 2,6-dimethyl-1,4-benzoquinone or simple 1,4-benzoquinone
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Oxidation-reduction condensation using in situ formed alkoxydiphenylphosphines, 2,6-dimethy-1,4-benzoquinone, and carboxylic acids provides a useful method for the preparation of inverted tertiary alkyl carboxylates from the corresponding chiral tertiary alcohols under mild and neutral conditions. Similarly, it has afforded alkyl carboxylates successfully in good-to-high yields by the combined use of alkoxydiphenylphosphines having primary, secondary, or tertiary alkoxy groups, carboxylic acids, and simple 1,4-benzoquinone. When chiral secondary or tertiary alcohols are used, the corresponding inverted secondary or tertiary alkyl carboxylates are also obtained in good-to-high yields. In addition, a convenient method for the preparation of phenyl carboxylates in high yields has been established by utilizing oxidation-reduction condensation in toluene at 110 °C using phenoxydiphenylphosphines in situ-formed from phenols and chlorodiphenylphosphine, 2,6-dimethyl-1,4-benzoquinone, and carboxylic acids.
- Shintou, Taichi,Fukumoto, Kentaro,Mukaiyama, Teruaki
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p. 1569 - 1579
(2007/10/03)
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- 1,3,4-Thiadiazole derivatives. Synthesis, structure elucidation, and structure-antituberculosis activity relationship investigation
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A series of 2,5-disubstituted-1,3,4-thiadiazoles were synthesized, the compounds structures were elucidated and screened for the antituberculosis activity against Mycobacterium tuberculosis H37Rv using the BACTEC 460 radiometric system. Among the tested compounds, 2-phenylamino-5-(4-fluorophenyl) -1,3,4-thiadiazole 22 showed the highest inhibitory activity. The relationships between the structures of compounds and their antituberculosis activity were investigated by the Electronic-Topological Method (ETM) and feed forward neural networks (FFNNs) trained with the back-propagation algorithm. As a result of the approach, a system of pharmacophores and anti-pharmacophores has been found that effectively separates compounds of the examination set into groups of active and inactive compounds. The system can be applied to the screening and design of new active compounds possessing skeletons similar to those used in the present study.
- Oru?, El?in E.,Rollas, Sevim,Kandemirli, Fatma,Shvets, Nathaly,Dimoglo, Anatholy S.
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p. 6760 - 6767
(2007/10/03)
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- Highly selective and efficient catalyst for carbonylation of aryl iodides: Dimeric palladium complex containing carbon-palladium covalent bond
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Dimeric cyclometallated oxime palladium complex containing palladium-carbon covalent bond was found to efficiently catalyze the carbonylation reactions of aryl iodides with various alcohols to give esters in excellent yields with high selectivity. These complexes were also stable under a carbon monoxide atmosphere at high temperatures.
- Ramesh, Chinnasamy,Kubota, Yoshihiro,Miwa, Minoru,Sugi, Yoshihiro
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p. 2171 - 2173
(2007/10/03)
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- Substituent effects on the base-catalysed hydrolysis of phenyl esters of para-substituted benzoic acids
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Seventeen model phenyl esters of 4-substituted benzoic acids were synthesised by the reaction of substituted benzoyl chlorides with phenol in aqueous alkaline solutions (Schotten-Baumann reaction), in pyridine (Einhorn reaction), or by the reaction of substituted benzoic acids with phosphorus oxychloride. Structures and purity of the model compounds were confirmed by 1H NMR and 13C NMR spectroscopy as well as by HPLC and elemental analysis. Phenyl 4-aminobenzoate was synthesised by reduction of phenyl 4-nitrobenzoate in methanol on palladium. Kinetics of base-catalysed hydrolysis of model phenyl esters occurring by the BAc2 mechanism were measured by UV spectrophotometry in 50% (v/v) aqueous dimethyl sulfoxide solutions at 25°C under pseudo-first-order conditions, (c[NaOH] = 0.001-1.0 mol l-1). The addition of OH- to phenyl benzoates was used to establish the kinetic J-E acidity scale. Linear relation between J-E and log kobs with the slope near unity was found for all the model compounds. The kinetic constants of hydrolysis of phenyl esters of 4-substituted benzoic acids precisely obey the Hammett relationship (σp) with ρ = 2.44. Quantitatively comparable results have been obtained by application of Alter-native Interpretation of Substituent Effects theory (AISE) using the σi set of substituent constants.
- Bauerova, Ingrid,Ludwig, Miroslav
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p. 1777 - 1790
(2007/10/03)
-