- Decatungstate anion as an efficient photocatalytic species for the transformation of the pesticide 2-(1-naphthyl)acetamide in aqueous solution
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The degradation and mineralization of the plant growth regulator 2-(1-naphthyl)acetamide (NAD) was studied by excitation in the presence of the catalyst polyoxometalate decatungstate anion (W10O324?) in aqueous solution under UV (365 nm) or simulated solar light exposure. Our results indicate that the photocatalytic degradation of NAD is dependent on molecular oxygen concentration: in aerated conditions, 95% degradation was achieved after 22 h irradiation, and followed first-order kinetics with a rate constant of 3.2 × 10?3 min?1, while under de-aerated conditions almost no degradation was observed (6.0% after 22 h). Upon UV irradiation, the catalyst W10O324? enhanced NAD photodegradation by a factor of about 20 compared to its direct degradation. Oxygen appeared to play a key role on the regeneration of the catalyst, promoting the photocatalytic cycle. The primary photoproducts of NAD photocatalytic degradation were assessed by LC-ESI–MS/MS, from which a mechanism of degradation involving electron transfer and hydrogen atom abstraction is proposed. Under these conditions, mono- and di-hydroxylated and oxidized products similar to those obtained under direct photolysis have been identified. In addition, tri-hydroxylation and hydroxyl-naphthoquinone products have been identified exclusively when photolysis was carried out in presence of this catalyst. For prolonged photolysis times, it is expected that the irradiation of the tri-hydroxylated products leads to the opening of the aromatic ring and to mineralization. Furthermore, mineralization was achieved, and led to the formation of the inorganic ions NO2? (?1), NO3? (2.6 mg L?1) and NH4+ (?1).
- Sousa Da Silva, Eliana,Sarakha, Mohamed,Burrows, Hugh D.,Wong-Wah-Chung, Pascal
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Read Online
- Radical chemistry of glucosamine naphthalene acetic acid and naphthalene acetic acid: A pulse radiolysis study
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Free radical-induced oxidation reactions of glucosamine naphthalene acetic acid (GNaa) and naphthalene acetic acid (Naa) have been studied using pulse radiolysis. GNaa was synthesized by covalently attaching Naa on glucosamine. Hydroxyl adduct (from the reaction of hydroxyl radicals (?OH) at the naphthalene ring) was identified as the major transient intermediate (suggesting that the ?OH reaction is on the naphthalene ring) and is characterized by its absorption maxima of 340 and 400 nm. Both GNaa and Naa undergo similar reaction pattern. The bimolecular rate constants determined for the reactions are 4.8 × 109 and 8.9 × 109 dm3 mol-1 s-1 for GNaa and Naa respectively. The mechanism of reaction of ?OH with GNaa was further confirmed using steady-state method. Radical cation of GNaa was detected as an intermediate during the reaction of sulfate radical (SO4 ?-) with GNaa (k2 = 4.52 × 109 dm3 mol-1 s-1). This radical cation transforms to a ?OH adduct at higher pH. The radical cation of GNaa is comparatively long lived, and a cyclic transition state by neighboring group participation accounts for its stability. The oxy radical anion (O ?-) reacts with GNaa (k2 = 1.12 × 10 9 dm3 mol-1 s-1) mainly by one-electron transfer mechanism. The reduction potential values of Naa and GNaa were determined using cyclic voltammetric technique, and these are 1.39 V versus NHE for Naa and 1.60 V versus NHE for GNaa.
- Shibin, Naduvilpurakkal B.,Sreekanth, Radhakrishnan,Aravind, Usha K.,Afsal Mohammed, Kadavilpparampu M.,Chandrashekhar, Narayana V.,Joseph, Jayan,Sarkar, Sisir K.,Naik, Devidas B.,Aravindakumar, Charuvila T.
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Read Online
- Preparation method of naphthalene ring C marked α .
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The invention discloses C labeled α - naphthalene acetic acid preparation method and belongs to the field of radioisotope C labeled compounds. C-labeled α - naphthylacetic acid preparation method, C radioisotope labeling is introduced on a naphthalene ring structure α -naphthol acid, C labeling site is in α-position. The method has the advantages that the reaction raw materials are easily available, the synthesis steps are high in yield, the total yield is more 60%, C marker isotopes are less in use amount, and waste is generated. The marker site α-position on the naphthalene ring is less likely to be metabolized compared to C-labeled branched acetic acid, and the synthesized C-labeled compound provides a better study of α -naphthoic acid in the environment.
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Paragraph 0046-0047; 0052-0057; 0062-0067; 0072-0075
(2021/10/05)
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- Desulfonylative Electrocarboxylation with Carbon Dioxide
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Electrocarboxylation of organic halides is one of the most investigated electrochemical approaches for converting thermodynamically inert carbon dioxide (CO2) into value-added carboxylic acids. By converting organic halides into their sulfone derivatives, we have developed a highly efficient electrochemical desulfonylative carboxylation protocol. Such a strategy takes advantage of CO2as the abundant C1 building block for the facile preparation of multifunctionalized carboxylic acids, including the nonsteroidal anti-inflammatory drug ibuprofen, under mild reaction conditions.
- Zhong, Jun-Song,Yang, Zi-Xin,Ding, Cheng-Lin,Huang, Ya-Feng,Zhao, Yi,Yan, Hong,Ye, Ke-Yin
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supporting information
p. 16162 - 16170
(2021/09/02)
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- Hydrolysis of amides to carboxylic acids catalyzed by Nb2O5
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Hydrolysis of amides to carboxylic acids is an industrially important reaction but is challenging due to the difficulty of cleaving the resonance stabilized amidic C-N bond. Twenty-three heterogeneous and homogenous catalysts were examined in the hydrolysis of acetamide. Results showed that Nb2O5was the most effective heterogeneous catalyst with the greatest yield of acetic acid. A series of Nb2O5catalysts calcined at various temperatures were characterized and tested in the hydrolysis of acetamide to determine the effects of crystal phase and surface properties of Nb2O5on catalytic performance. The high catalytic performance observed was attributed mainly to the facile activation of the carbonyl bond by Lewis acid sites that function even in the presence of basic inhibitors (NH3and H2O). The catalytic studies showed the synthetic advantages of the present method, such as simple operation, catalyst recyclability, additive free, solvent free, and wide substrate scope (>40 examples; up to 95% isolated yield).
- Siddiki,Rashed, Md. Nurnobi,Touchy, Abeda Sultana,Jamil, Md. A. R.,Jing, Yuan,Toyao, Takashi,Maeno, Zen,Shimizu, Ken-Ichi
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p. 1949 - 1960
(2021/03/26)
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- Naphthylacetic acid preparation method
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The invention discloses a naphthylacetic acid preparation method, which comprises: naphthylacetic acid is prepared by using 1-chloromethylnaphthalene as a starting raw material, using cuprous iodide as a catalyst, using potassium ferrocyanide as a cyanide source and adding triethyl benzyl ammonium chloride as a phase transfer catalyst into a reaction system. According to the invention, traditionalpotassium cyanide or sodium cyanide is replaced with potassium ferrocyanide as the cyanide source, so the safety threat of potassium cyanide or sodium cyanide to operators in a production process isavoided, and environment pollution caused by highly toxic substances is reduced; and the preparation method has advantages of simple post-treatment, low energy consumption and few three-waste.
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Paragraph 0037; 0041-0046; 0047; 0051-0056; 0057; 0061-0067
(2020/03/12)
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- Preparation method 1 - naphthalene acetic acid (by machine translation)
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The invention belongs to the field of pesticide synthesis, and particularly relates to a preparation method 1 - naphthalene acetic acid. The method comprises the following steps: adding naphthalene and chloroacetic acid into a reactor to obtain a mixture containing 1 - naphthalene acetic acid and excessive chloroacetic acid; and carrying out solid-liquid separation to obtain 1 - naphthalene acetic acid and mother liquor. 1 - Naphthalene acetic acid is continuously produced, byproduct generation is greatly reduced, the problem of recovery of excessive chloroacetic acid is solved, the complex separation step is omitted, the production cost is greatly reduced, and the method is suitable for large-scale continuous production 1 - naphthylacetic acid. (by machine translation)
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Paragraph 0032-0039
(2020/06/05)
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- Preparation method of alpha-naphthylacetic acid
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The invention relates to the technical field of organic synthesis, and provides a preparation method of alpha-naphthylacetic acid. The invention aims to solve the problem that preparation of alpha-naphthylacetic acid is not economical and environmentally friendly in the prior art. The preparation method comprises the following steps: (1) dissolving naphthalene and Lewis acid in a solvent, carryingout heating, adding oxalyl chloride monoester, and carrying out a reaction to generate alpha-acetonaphthone acid ester; and (2) adding the alpha-acetonaphthone acid ester obtained in the step (1) andhydrazine hydrate into a high-boiling-point alcohol solvent, carrying out a heating reaction, adding a strong base, continuing the heating reaction, and adjusting a pH value to an acidic state afterthe reaction is finished so as to obtain alpha-naphthylacetic acid. According to the method, naphthalene and oxalyl chloride monoester which are cheap and easy to obtain are used as raw materials, alpha-acetonaphthone acid ester is prepared under the action of Lewis acid, and then a series of reactions are performed under the action of hydrazine hydrate to generate alpha-naphthylacetic acid, so the use of highly toxic cyanide is avoided, highly toxic or foul gas is not generated in the reaction process, only one product is produced, reaction conditions are mild, yield is high and cost is low.
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Paragraph 0009; 0021-0022; 0025-0026
(2020/08/22)
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- Coumarin-Caged Compounds of 1-Naphthaleneacetic Acid as Light-Responsive Controlled-Release Plant Root Stimulators
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Six coumarin-caged compounds of 1-naphthaleneacetic acid (NAA) comprising different substituents on the coumarin moiety were synthesized and evaluated for their photophysical and chemical properties as light-responsive controlled-release plant root stimulators. The 1H NMR and HPLC techniques were used to verify the release of NAA from the caged compounds. After irradiation at 365 nm, the caged compounds exhibited the fastest release rate at t1/2 of 6.7 days and the slowest release rate at t1/2 of 73.7 days. Caged compounds at high concentrations (10-5 and 10-6 M) significantly stimulate secondary root germination while free NAA at the same level is toxic and leads to inhibition of secondary root germination. The cytotoxicity of the caged compounds against fibroblasts and vero cells were evaluated, and the results suggested that, at 10-5-10-6 M, caged compounds exhibited no significant cytotoxicity to the cells. Thus, the caged compounds of NAA in this study could be of great benefit as efficient agrochemicals.
- Han, Bao-Hang,Jarussophon, Suwatchai,Kaewchangwat, Narongpol,Niamnont, Nakorn,Prateepchinda, Sagaw,Suttisintong, Khomson,Thanayupong, Eknarin,Unger, Onuma,Yata, Teerapong
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p. 6268 - 6279
(2020/07/31)
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- Oxidation of Alkynyl Boronates to Carboxylic Acids, Esters, and Amides
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A general efficient protocol was developed for the synthesis of carboxylic acids, esters, and amides through oxidation of alkynyl boronates, generated directly from terminal alkynes. This protocol represents the first example of C(sp)?B bond oxidation. This approach displays a broad substrate scope, including aryl and alkyl alkynes, and exhibits excellent functional group tolerance. Water, primary and secondary alcohols, and amines are suitable nucleophiles for this transformation. Notably, amino acids and peptides can be used as nucleophiles, providing an efficient method for the synthesis and modification of peptides. The practicability of this methodology was further highlighted by the preparation of pharmaceutical molecules.
- Li, Chenchen,Li, Ruoling,Zhang, Bing,Zhao, Pei,Zhao, Wanxiang
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supporting information
p. 10913 - 10917
(2020/05/25)
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- BF3·OEt2-promoted tandem Meinwald rearrangement and nucleophilic substitution of oxiranecarbonitriles
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Tandem Meinwald rearrangement and nucleophilic substitution of oxiranenitriles was realized. Arylacetic acid derivatives were readily synthesized from 3-aryloxirane-2-carbonitriles with amines, alcohols, or water in the presence of boron trifluoride under microwave irradiation, and the designed synthetic strategy includes introducing a cyano leaving group into arylepoxides and capturing the in situ generated toxic cyanide with boron trifluoride, making the reaction efficient, safe, and environmentally benign. The reaction occurs through an acid-promoted Meinwald rearrangement, producing arylacetyl cyanides, followed by an addition-elimination process with nitrogen or oxygen-containing nucleophilic amines, alcohols or water. The current method provides a new application of the tandem Meinwald rearrangement.
- Xu, Chuangchuang,Xu, Jiaxi
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p. 127 - 134
(2019/12/26)
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- Preparation method of acid with different substituent groups
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The invention discloses a preparation method of an acid with different substituent groups. A terminal alkyne is lithiated with n-butyllithium, and then reacts with isopropoxyboronic acid pinacol ester, hydrogen chloride is added to achieve quenching, then the obtained reaction product is oxidized by an oxidizing agent, and the oxidized reaction product is separated and purified to obtain the acid.The method of the invention has the advantages of simplicity in operation, one-pot process preparation, no metal catalysis, nontoxic reagents, greenness, environmental friendliness and high atomic utilization rate, and provides a novel and quick way for preparing the acid with different substituent groups; and the obtained acid is an important fine chemical product, and can be widely used in fields of medicines, pesticides, spices and other industries.
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Paragraph 0083-0087
(2019/10/23)
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- A 4-OTBS benzyl-based protective group for carboxylic acids
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Reported herein is a novel 4-OTBS benzyl-based protective group for carboxylic acids. This protective group can be removed in the presence of TBAF or TFA with high efficiency, which makes it compatible with base-sensitive or acid-sensitive substrates. With this protective group, a near-infrared fluorogenic probe for the detection of γ-glutamyltranspeptidase activities was readily prepared.
- Fang, Zhijun,Li, Yuyao,Xie, Hexin
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supporting information
p. 1658 - 1662
(2019/05/29)
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- Organocatalyzed Aerobic Oxidation of Aldehydes to Acids
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The first example organocatalyzed aerobic oxidation of aldehydes to carboxylic acids in both organic solvent and water under mild conditions is developed. As low as 5 mol % N-hydroxyphthalimide was used as the organocatalyst, and molecular O2 was used as the sole oxidant. No transition metals or hazardous oxidants or cocatalysts were involved. A wide range of carboxylic acids bearing diverse functional groups were obtained from aldehydes, even from alcohols, in high yields.
- Dai, Peng-Fei,Qu, Jian-Ping,Kang, Yan-Biao
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supporting information
p. 1393 - 1396
(2019/02/26)
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- A aldehyde or mellow directly converted into the carboxylic acid (by machine translation)
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The invention discloses a aldehyde or mellow oxidation can be directly transformed into carboxylic acid, is characterized in that the pure oxygen environment, in N - hydroxy imide compound under the catalysis of the imide compound or N - hydroxy and nitrous acid ester compound common under the catalysis, the CH2 OH and CHO oxidation directly converted into the carboxylic acid compounds. The invention using oxygen as the oxidizing agent, does not add any metal catalyst, environment-friendly, high catalytic efficiency, simple and convenient operation. With the previous metal catalytic system complex and different catalytic system, has some metal catalytic system in the process, the use of transition metal will cause the transition metal of the residual, the invention adopts the non-metallic catalytic system, environmental protection, preventing the metal residue problem, this to the solution of the drug in the synthesis of transition metal residue problem and provides a new method of thinking. (by machine translation)
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Paragraph 0059-0061
(2018/08/03)
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- Ruthenium-catalyzed umpolung carboxylation of hydrazones with CO2
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The first ruthenium-catalyzed umpolung carboxylation of hydrazones with CO2 to generate important aryl acetic acids is reported. Besides aldehyde hydrazones, a variety of ketone hydrazones, which have not been successfully applied in previous umpolung reactions with other reactive electrophiles, also show high reactivity and selectivity under mild conditions. Moreover, this operationally simple protocol features good functional group tolerance, is readily scalable, and offers easy derivation of important structures, including bioactive felbinac and adiphenine. Computational studies reveal that this umpolung reaction proceeds through the generation of a Ru-nitrenoid followed by concerted [4 + 2] cycloaddition with CO2.
- Yan, Si-Shun,Zhu, Lei,Ye, Jian-Heng,Zhang, Zhen,Huang, He,Zeng, Huiying,Li, Chao-Jun,Lan, Yu,Yu, Da-Gang
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p. 4873 - 4878
(2018/06/07)
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- A General, Activator-Free Palladium-Catalyzed Synthesis of Arylacetic and Benzoic Acids from Formic Acid
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A new catalyst for the carboxylative synthesis of arylacetic and benzoic acids using formic acid (HCOOH) as the CO surrogate was developed. In an improvement over previous work, CO is generated in situ without the need for any additional activators. Key to success was the use of a specific system consisting of palladium acetate and 1,2-bis((tert-butyl(2-pyridinyl)phosphinyl)methyl)benzene. The generality of this method is demonstrated by the synthesis of more than 30 carboxylic acids, including non-steroidal anti-inflammatory drugs (NSAIDs), under mild conditions in good yields.
- Wang, Lin,Neumann, Helfried,Beller, Matthias
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supporting information
p. 6910 - 6914
(2018/06/04)
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- Bimane: A Visible Light Induced Fluorescent Photoremovable Protecting Group for the Single and Dual Release of Carboxylic and Amino Acids
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A series of ester conjugates of carboxylic and amino acids were synthesized based on bimane fluorescent photoremovable protecting group (FPRPG). The photorelease of single and dual (same as well as different) carboxylic and amino acids is demonstrated from a single bimane molecule on irradiation with visible light (λ ≥ 410 nm). The detailed mechanistic study of photorelease revealed that the release of two caged acids is simultaneous but in a stepwise pathway.
- Chaudhuri, Amrita,Venkatesh, Yarra,Behara, Krishna Kalyani,Singh, N. D. Pradeep
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supporting information
p. 1598 - 1601
(2017/04/13)
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- Catalytic hydrolysis of hydrophobic esters on/in water by high-silica large pore zeolites
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Hydrolysis of water-insoluble esters is an industrially important but challenging reaction, because the esters are mostly present in oil droplets on water during the reaction. On the basis of the screening results for hydrolysis of a water-insoluble ester, 3-phenylpropionate, on/in water by 25 types of heterogeneous and homogenous catalysts, we have found that Hβ zeolite with a moderate Si/Al ratio (Si/Al = 75), Hβ-75, is an effective and reusable catalyst for hydrolysis of hydrophobic esters. The hydrolysis of esters with different sizes is studied by Hβ and HZSM5 zeolites with different Si/Al ratios, and the results show the hydrophobicity, pore size and number of Br?nsted acid sites are critical factors affecting the catalytic activity for this system. Kinetic and adsorption studies show that the high yields by Hβ-75 are due to preferential interaction of the hydrophobic zeolite pore with hydrophobic esters over polar molecules (carboxylic acids, water, alcohols) and transfer of the carboxylic acids to the oil droplets on water, both of which inhibit the reverse reaction (esterification of the carboxylic acids).
- Siddiki,Toyao, Takashi,Kon, Kenichi,Touchy, Abeda S.,Shimizu, Ken-ichi
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p. 741 - 748
(2016/12/09)
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- Ni-catalyzed carboxylation of C(sp2)- and C(sp3)-O bonds with CO2
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In recent years a significant progress has been made for the carboxylation of aryl and benzyl halides with CO2, becoming convenient alternatives to the use of stoichiometric amounts of well-defined metal species. Still, however, most of these processes require the use of pyrophoric and air-sensitive reagents and the current methods are mostly restricted to organic halides. Therefore, the discovery of a mild, operationally simple alternate carboxylation that occurs with a wide substrate scope employing readily available coupling partners will be highly desirable. Herein, we report a new protocol that deals with the development of a synergistic activation of CO2 and a rather challenging activation of inert C(sp2)-O and C(sp3)-O bonds derived from simple and cheap alcohols, a previously unrecognized opportunity in this field. This unprecedented carboxylation event is characterized by its simplicity, mild reaction conditions, remarkable selectivity pattern and an excellent chemoselectivity profile using air-, moisture-insensitive and easy-to-handle nickel precatalysts. Our results render our method a powerful alternative, practicality and novelty aside, to commonly used organic halides as counterparts in carboxylation protocols. Furthermore, this study shows, for the first time, that traceless directing groups allow for the reductive coupling of substrates without extended π-systems, a typical requisite in many C-O bond-cleavage reactions. Taking into consideration the limited knowledge in catalytic carboxylative reductive events, and the prospective impact of providing a new tool for accessing valuable carboxylic acids, we believe this work opens up new vistas and allows new tactics in reductive coupling events.
- Correa, Arkaitz,Leon, Thierry,Martin, Ruben
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supporting information
p. 1062 - 1069
(2014/02/14)
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- Fluorescent photoremovable precursor (acridin-9-ylmethyl)ester: Synthesis, photophysical, photochemical and biological applications
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A series of carboxylic acids including amino acids were protected as their corresponding fluorescent ester conjugates by coupling with an environment sensitive fluorophore 9-methylacridine. Photophysical properties of all the ester conjugates along with the protecting group have been investigated. Interestingly, the emission properties of the ester conjugates and 9-methylacridine were found to be highly sensitive to polarity, H-bonding and pH of the environment. Photolysis of all the ester conjugates was carried out using UV light above 360 nm and it was found that in every case the corresponding carboxylic acids were released in high chemical yield. Further, intercalation and the preferred binding mode of acridine-9-methanol and its ester conjugates with DNA were studied. In vitro biological studies revealed that acridine-9-methanol has good biocompatibility, cellular uptake property and cell imaging ability. The Royal Society of Chemistry and Owner Societies 2013.
- Jana, Avijit,Saha, Biswajit,Karthik,Barman, Sharabani,Ikbal, Mohammed,Ghosh, Sudip Kumar,Pradeep Singh
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p. 1041 - 1052
(2013/09/12)
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- PROCESS FOR SYNTHESIZING PHENYLACETIC ACID BY CARBONYLATION OF TOLUENE
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A production process for substituted phenylacetic acids or ester analogues thereof is disclosed. In this process toluene or toluene substituted with various substituents, an alcohol, an oxidant and carbon monoxide are used as raw materials to obtain compounds comprising structure of phenylacetic acid ester or analogues thereof by catalysis of the complex catalyst formed from transition metal and ligand, and such compounds are hydrolyzed to obtain various substituted phenylacetic acid based compounds. This type of compounds and their derivatives serve as important fine chemicals used widely in the industries of pharmaceuticals, pesticides, perfume and the like.
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Paragraph 0018; 0072; 0073
(2013/11/19)
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- An efficiently cobalt-catalyzed carbonylative approach to phenylacetic acid derivatives
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A highly efficient cobalt-catalyzed carbonylative approach to phenylacetic acid derivatives under one atmosphere pressure is reported. This methodology represents a useful extension of benzimidazole used as ligand in metal catalysis, and the catalytic mechanism has been proved by computer simulation. Notably, this new cobalt precatalyst, which promotes the carbonylation reaction dramatically and has already been used for scale-up experiment of phenylacetic acid derivatives.
- She, Meng-Yao,Xiao, Da-Wei,Yin, Bing,Yang, Zheng,Liu, Ping,Li, Jian-Li,Shi, Zhen
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p. 7264 - 7268
(2013/08/23)
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- Synthesis, characterization and slow release properties of O-naphthylacetyl chitosan
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O-naphthylacetyl chitosan (NA-chitosan) was first prepared via protecting the amino groups with phthalic anhydride, followed by reaction with 1-naphthylacetyl chloride. The intermediates were hydrolyzed with anhydrous hydrazine to obtain final product. The derivatives of each step were characterized with Fourier transform infrared spectroscopy (FT-IR) and 13C solid state nuclear magnetic resonance (NMR). Results showed NA-chitosan had both naphthylacetyl and amino groups in the main chain of the polysaccharide. Elemental analysis showed that the substitution degree of hydroxyl was 0.4. Thermogravimetric analysis (TGA, DTG) of NA-chitosan was observed with much lower decomposition peak at 283°C than that of chitosan at 300°C. The release of 1-naphthylacetic acid was dependent on both pH values and the medium temperature, and at pH 12.0, 60°C the release period could last for 55 days.
- Tao, Shuming,Pang, Ran,Chen, Chao,Ren, Xueqin,Hu, Shuwen
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experimental part
p. 1189 - 1194
(2012/07/13)
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- Transition-Metal-Free carboxylation of organozinc reagents using CO 2 in DMF solvent
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An efficient process for the carboxylation of functionalized organozinc reagents with CO2 under transition-metal-free conditions was developed by employing DMF solvent in the presence of LICl.
- Kobayashi, Koji,Kondo, Yoshinori
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supporting information; experimental part
p. 2035 - 2037
(2009/09/08)
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- Exceptionally simple catalytic system for the carbonylation of benzyl halides
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A ligand-less catalytic system, Pd(OAc)2 immobilized in NBu4Hal melt is suggested for the synthesis of arylacetic acids by the carbonylation of benzyl bromides.
- Lapidus, Albert L.,Eliseev, Oleg L.,Bondarenko, Tatyana N.,Chau, Nguen H.,Kazantsev, Ruslan V.
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scheme or table
p. 256 - 257
(2010/01/18)
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- FRET-based fluorescence probes for hydrolysis study and pig liver esterase activity
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New fluorescent probes based on simple organic synthesis were designed and synthesized, and their hydrolysis catalyzed via base and pig liver esterase (PLE) was studied using FRET (fluorescence resonant energy transfer), with 1-naphthylacetic group as a donor and dansyl group as an acceptor. By simultaneous recording of changes of the donor fluorescence intensities, kinetic parameters for base-catalyzed and PLE-catalyzed hydrolysis can be determined. The presented FRET assay is a convenient and simple method and both fluorescent probes are good real-time indicators for the analysis of ester hydrolysis such as PLE activities.
- Yi, Long,Cao, Li,Liu, Liangliang,Xi, Zhen
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p. 8947 - 8951
(2008/12/21)
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- Fluorochromate-catalyzed periodic acid oxidation of alcohols and aldehydes
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Preparation of aldehydes and ketones from alcohols, and carboxylic acids from alcohols and aldehydes using pyridinium fluorochromate (PFC) as a catalyst and H5IO6 as the terminal oxidant is described here.
- Hunsen, Mo
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p. 1356 - 1360
(2007/10/03)
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- Carboxylic acids from primary alcohols and aldehydes by a pyridinium chlorochromate catalyzed oxidation
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A facile and quantitative preparation of carboxylic acids by a pyridinium chlorochromate (PCC) catalyzed (2 mol%) oxidation of primary alcohols and aldehydes using 2.2 equivalents and 1.1 equivalents of H5IO 6, respectively, in acetonitrile is described here. Georg Thieme Verlag Stuttgart.
- Hunsen, Mo
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p. 2487 - 2490
(2007/10/03)
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- Influence of hydrogen bonding in the activation of nucleophiles: PhSH- (catalytic) KF in N-methyl-2-pyrrolidone as an efficient protocol for selective cleavage of alkyl/aryl esters and aryl alkyl ethers under nonhydrolytic and neutral conditions
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The nucleophilicity of arenethiols can be augmented via hydrogen bonding with 'naked' halide anion. The activity of the halide anions follow the order F- ?Cl- ～ Br- ～ I- and is dependent on the countercation (Bu4N ～ Cs ～ K > Na ?Li). The solvent plays an important role in nucleophilic activation as well as regeneration of the effective nucleophile (e.g. ArS-) and those with high dielectric constant, high molecular polarizability, high donor number (DN), and low acceptor number (AN) are the most effective. Selective deprotection of alkyl/aryl esters and aryl alkyl ethers can be achieved under nonhydrolytic and neutral conditions by the treatment with thiophenol in 1-methyl-2-pyrrolidone (NMP) in the presence of a catalytic amount of KF. Aryl esters are selectively deprotected in the presence of alkyl esters and alkyl methyl ethers during intramolecular competitions.
- Chakraborti, Asit K.,Sharma, Lalima,Nayak, Mrinal K.
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p. 2541 - 2547
(2007/10/03)
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- A stereospecific '2-aza-divinylcyclopropane' rearrangement
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The stereochemical course of the thermal 2-aza-Cope rearrangement of the optically pure acyl azide (-)-(1S)-5 was investigated by determination of the absolute configuration of the rearrangement product (1R,8S)-9. The reaction proceeds by a sequence of stereospecific steps from 5 to an equilibrating mixture of exo- and endo-isocyanates 6 and 7. The endo-isomer 7 undergoes Cope rearrangement to the putative intermediate 8, which is trapped and characterized as the adduct 9b of butan-1-ol. The absolute configuration of 9b was determined by its reduction to the amide 20, and determination of the X-ray structure of the N-camphanoylamide 21 derived from camphanic acid of known absolute configuration.
- Mueller, Paul,Toujas, Jean-Louis,Bernardinelli, Gerald
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p. 1525 - 1534
(2007/10/03)
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- A mild and chemoselective method for ester O - Alkyl cleavage using in situ generated potassium thiophenoxide from catalytic quantities of base
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Chemoselective deprotection of methyl esters can be achieved under non- hydrolytic and virtually neutral conditions by treatment with thiophenol in N-methyl-2-pyrrolidone (NMP) in the presence of a catalytic amount of K2CO3.
- Sharma, Lalima,Nayak, Mrinal K.,Chakraborti, Asit K.
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p. 9595 - 9600
(2007/10/03)
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- Solvent isotope effect on the hydroxide-ioncatalyzed hydration of ketenes in aqueous solution
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Five ketenes, phenyl(ethyl)ketene, phenyl(methylthio)ketene, diphenylketene, pentafluorophenylketene, and 1-naphthylketene, were generated flash photolytically and solvent isotope effects (H2O vs. D2O) on their hydroxide-ioncatalyzed hydration in aqueous solution were determined. The values obtained are all weakly reverse and closely similar (k(HO)/k(DO) = 0.76-0.97), as expected for these fast, hydroxide-ion-consuming reactions, known to proceed by nucleophilic attack of hydroxide on the ketene carbonyl group. The characteristic magnitude of these isotope effects should prove useful in identifying new examples of this reaction.
- Andraos,Chiang,Eustace,Kresge,Paine,Popik,Sung
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p. 459 - 462
(2007/10/03)
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- PhSH - (catalytic) KF as an efficient protocol for chemoselective ester O-alkyl cleavage under non-hydrolytic neutral condition
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Methyl esters are chemoselectively deprotected by thiophenol in presence of catalytic amount of KF in dry NMP (1-Methyl-2-pyrrolidinone) under non-hydrolytic neutral condition.
- Nayak, Mrinal K.,Chakraborti, Asit K.
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p. 297 - 298
(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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- Efficient transformations of aldehydes and ketones into one-carbon homologated carboxylic acids
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Peterson olefination of aldehydes and ketones with trimethylsilyl(methoxy)(benzotriazol-1-yl)methyl anion 6 afforded 1-(benzotriazol-1-yl)-1-methoxyalk-1-enes 7 which were treated without isolation with zinc bromide and hydrochloric acid, to yield the corresponding one-carbon homologated carboxylic acids 4 in good overall yields.
- Katritzky, Alan R.,Toader, Dorin,Xie, Linghong
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p. 1425 - 1427
(2007/10/03)
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- Flash photolytic generation and study of ynolate ions and the corresponding ketenes in aqueous solution
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Flash photolysis of a series of arylhydroxycyclopropenones (aryl = phenyl, mesityl, 4-methoxyphenyl, 2,4,6-trimethoxyphenyl, and 1-naphthyl) in aqueous solution was found to give arylacetic acids as final products through two successively formed, short-lived reaction intermediates. Rate profiles, the form of acid-base catalysis, and solvent isotope effects identified the first of these intermediates as arylynolate ions, ArC≡CO-, and the second as arylketenes, ArCH=C=O; the identity of the ketenes was also confirmed by independent generation through photo-Wolff reaction of corresponding aryl diazo compounds. The kinetic behavior of the arylynolate ions shows that the corresponding arylynols, ArC≡COH, are remarkably strong acids, with pKa 3.
- Chiang,Kresge,Popik
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p. 9165 - 9171
(2007/10/02)
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- Ligand exchange reaction of sulfoxides in organic synthesis: A new method for one-carbon homologation of esters to carboxylic acids and esters via α- chloro α-sulfinyl ketones
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Reaction of the Carbanion of chloromethyl phenyl sulfoxide with esters gave α-chloro α-sulfinyl ketones, which were treated with KH followed by t- BuLi to afford one-carbon homologated acids and esters in good to excellent yields.
- Satoh,Mizu,Hayashi,Yamakawa
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p. 133 - 134
(2007/10/02)
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- Generation of Radical-cations from Naphthalene and Some Derivatives, both by Photoionization and Reaction with SO4-.: Formation and Reactions Studied by Laser Flash Photolysis
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Radical-cations from naphthalene and some derivatives have been generated in aqueous acetonitrile both by direct photolysis (with λ 248 nm light via biphotonic ionization) and via reaction with SO4-..The radical-cation reacts rapidly with the parent substrate (k ca. 1E8 dm3 mol-1 s-1) and with nucleophiles (e. g. with N3- k = 4.2*1E9 dm3 mol-1 s-1 or with water, k 4*1E4 s-1 ).The radical-cation from 1-naphthylethanoic acid undergoes rapid decarboxylation (k 5*1E5 s-1).The radical cations from 4-methyl- and 4-methoxy-phenylethanoic acid also rapidly decarboxylate to yield the corresponding benzyl radicals.
- Steenken, Steen,Warren, Cathryn J.,Gilbert, Bruce C.
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p. 335 - 342
(2007/10/02)
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- Lanthanide-Promoted and Nickel Cyanide Catalyzed Carbonylation Reactions under Phase-Transfer Conditions
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The nickel cyanide and phase transfer catalyzed carbonylation of benzyl chlorides is promoted by lanthanide salts .This simple reaction is sensitive to the concentration of the lanthanide compound, sodium hydroxide, quaternary ammonium salt, and nickel catalyst.The nature of the organic phase and phase transfer agent also influences the reaction rate.The acceleration of the reaction may be a consequence of coordination of a nickel cyanide nitrogen lone pair to the lanthanide salt.
- Amer, Ibrahim,Alper, Howard
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p. 927 - 930
(2007/10/02)
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- INTER- AND INTRA-MOLECULAR PHOTOCYCLOADDITION OF ENOL ETHERS TO NAPHTHALENE
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The isomeric non-conjugated naphthyl enol ether bichromophores (6) and (7) display markedly different photoreactivities.The former undergoes ? + 2?> cycloaddition from the S1 state whereas the latter is relatively photostable.The two cyano derivatives (4) and (5) both yield intramolecular cycloadducts but the orientation of the addition is the opposite of that predicted from the reported intermolecular cyanonaphthalene-enol ether photoreactions. 2,3-Dihydrofuran undergoes specific "head to head" endo photoaddition to naphthalene but in contrast the major adducts from 2,3-dihydrofuran and this arene have "head to head" exo and "head to tail" endo structures.The adduct (18) undergoes a facile 1,3-shift to yield the (4? + 2?) endo adduct (19).The reactivities of the bichromophores and the regiochemistries of the additions are considered in relation to the relative charge densities at the 1- and 2-positions of the S1 arene.
- Gilbert, Andrew,Heath, Peter,Kashoulis-Koupparis, Annoula,Ellis-Davies, Graham C. R.,Firth, Susan M.
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- CONVENIENT SYNTHESIS AND FACILE CLEAVAGE OF PHENACYL ESTERS
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A convenient synthesis of phenacyl esters and a facile cleavage of them with sodium hydrogen telluride are described.
- Huang, Zhizhen,Xie, Linghong,Huang, Xian
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p. 1167 - 1170
(2007/10/02)
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- Photoreactivity of 1-Pyrenylmethyl Esters. Dependence on the Structure of the Carboxylic Acid Moieties and the Nature of the Excited States
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While the photolysis of 1-pyrenylmethyl phenylacetates in methanol gave the original phenylacetic acids, irradation of the 1-naphthoate and 9-anthracenecarboxylate leads to the formation of the intramolecular exciplexes that are inert to the photolysis.The Φf and τf values of these esters have been determined.
- Iwamura, Michiko,Tokuda, Kazuko,Koga, Noboru,Iwamura, Hiizu
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p. 1729 - 1732
(2007/10/02)
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- GENERATION AND REACTIONS OF CARBANIONS FROM DIALKYLAMINO(METHYLTHIO)ACETONITRILES
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Dialkylamino(methylthio)acetonitriles 1 have been prepared by two independent pathways.The carbanions generated from 1 in various base/solvent systems reacted with alkyl halides or electrophilic alkenes to give unstable products 2 and 5 respectively.These products were transformed into amides 3 or acids 4 and 6.On the other hand, carbanions from 1 with ethyl maleinate or ω-nitrostyrene afforded products of aliphatic vicarious nucleophilic substitution 7, while with 1-nitronaphthalene, the product of aromatic vicarious nucleophilic substitution 8.
- Jonczyk, Andrzej,Owczarczyk, Zbyslaw,Makosza, Mieczyslaw,Winiarski, Jerzy
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p. 303 - 310
(2007/10/02)
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- MILD HOMOGENOUS DEBLOCKING EMPLOYING 2-BROMO-1,3,2-BENZODIOXABOROLE
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We describe a technique using 2-bromo-1,3,2-benzodioxaborole in methylene chloride at ambient temperature to cleave ethers and esters.
- King, Patrick F.,Stroud, Stephen G.
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p. 1415 - 1418
(2007/10/02)
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- Esters of α-Arylalkanoic Acids from 'Masked' α-Halogenoalkyl Aryl Ketones and Silver Salts: Synthetic, Kinetic, and Mechanistic Aspects
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A method for the synthesis of alkyl esters of α-arylalkanoic acids is given based on silver-ion-assisted (AgBF4, AgOSO2CF3, AgSbF6, AgNO3) solvolysis of alkyl acetals of primary and secondary α-halogenoalkyl aryl ketones (Hal = I, Br, Cl) in an alcoholic medium (methanol, ethanol).The reaction is quite selective and alkyl esters are the only reaction products; ethers, which are possible substitution products, are not found.The importance of masking the carbonyl as the acetal is emphasised.The reaction is found to be first-order in AgBF4 and in the primary α-halogeno acetal.A three-point Hammett correlation (ρ = -3.29) between ?+ and the rate constants suggests a large cationic contribution as well as strong aryl participation in the transition state.The role payed by the oxygen of the acetal group in the specificity of the reaction is discussed in comparison with the reactivity of analogous compounds with saturated skeletons and of α-halogenoalkyl aryl ketones.
- Giordano, Claudio,Castaldi, Graziano,Casagrande, Francesco,Belli, Aldo
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p. 2575 - 2582
(2007/10/02)
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- SPECIFICALLY DEUTERATED AND TRITIATED AUXINS
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Regiospecific synthesis of monodeuterated and monotritiated natural auxin (indole-3-acetic acid), a synthetic auxin (naphthalene-1-acetic acid) and a photoaffinity labeling auxin (5-azidoindole-3-acetic acid) are described.These synthesis provide benzene-ring tritiated auxins for use in reversible and covalent binding studies. - Key Word Index: Auxin; azido auxin; indole-3-acetic acid; 5-azidoindole-3-acetic acid; napthalene-1-acetic acid; radiolabeling; photoaffinity labeling; synthesis.
- Melhado, L. Lee,Pearce, Cedric J.,d'Alarcao, Marc,Leonard, Nelson J.
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p. 2879 - 2886
(2007/10/02)
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