- A New Class of Linear Tetrapyrroles: Acetylenic 10,10a-Didehydro-10a-homobilirubins
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Novel bilirubin analogues with dipyrrinones conjoined to an acetylene rather than a methylene group were synthesized and examined spectroscopically. Despite the increased separation of the dipyrrinones forced by replacing a -CH2- by a -C≡C- unit, molecular dynamics calculations show that, like bilirubin, they may still engage in intramolecular hydrogen bonding to carboxylic acid groups when the propionic acid chains are slightly lengthened, e.g., butanoic acids. Unlike bilirubin, however, which is bent in the middle and has a ridge-tile shape, the acetylene orients the attached dipyrrinones along a linear path, and intramolecular hydrogen bonding preserves a twisted linear molecular shape. The extended planes of the dipyrrinones intersect along the -C≡C- axis at an angle of 136° for the conformation stabilized by intramolecular hydrogen bonding in the bis-butyric acid rubin (lb). With shorter acid chains (propionic), only one CO2H can engage an opposing dipyrrinone in intramolecular hydrogen bonding, and in this energy-minimum conformation of the linear pigment 1a, the intersection of the extended planes of the dipyrrinones has an angle of 171°. Spectroscopic evidence for such linearized and twisted structures was found in the pigments' NMR spectral data and their exciton UV-vis and induced circular dichroism spectra.
- Tu, Bin,Ghosh, Brahmananda,Lightner, David A.
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- Tetracarboxylatoplatinum(IV) complexes featuring monodentate leaving groups - A rational approach toward exploiting the platinum(IV) prodrug strategy
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A series of novel symmetrically and unsymmetrically coordinated platinum(IV) complexes with monodentate carboxylato ligands was synthesized. The compounds exhibit a general coordination sphere of [Pt(en)(OCOR)2(OCOR′)(OCOR″], where the carboxylato ligands are represented by acetato and succinic acid monoester ligands. Dicarboxylatoplatinum(II) complexes were synthesized and oxidized symmetrically or unsymmetrically to obtain platinum(IV) complexes, which were subsequently carboxylated with noncyclic anhydrides. The compounds were investigated in detail by elemental analysis, mass spectrometry, infrared and multinuclear (1H, 13C, 15N, 195Pt) NMR spectroscopy as well as by X-ray diffraction in some cases. The reduction behavior was followed by NMR spectroscopy, while stability and lipophilicity were examined by analytical reversed phase HPLC measurements. Cytotoxic properties were studied in three human cancer cell lines derived from cisplatin sensitive ovarian teratocarcinoma (CH1/PA-1), cisplatin insensitive colon carcinoma (SW480) and non-small cell lung cancer (A549). Thereby, the most lipophilic (yet water soluble) platinum(IV) complexes showed promising IC50 values in the low micromolar and even nanomolar range, demonstrating the significant advantage of using equatorially coordinated monodentate carboxylato ligands.
- H?fer, Doris,Varbanov, Hristo P.,Legin, Anton,Jakupec, Michael A.,Roller, Alexander,Galanski, Markus,Keppler, Bernhard K.
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- Novel sulfonated carbonaceous materials from p-toluenesulfonic acid/glucose as a high-performance solid-acid catalyst
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A novel carbon-based solid-acid catalyst was simply prepared for the first time by the thermal treatment of p-toluenesulfonic acid (TsOH) with d-glucose at 180 °C in a sealed autoclave and it was proved to have high acidity and to be a highly efficient solid-acid catalyst in the reactions such as esterification of succinic acid with ethanol. Crown Copyright
- Zhang, Baohua,Ren, Jiawen,Liu, Xiaohui,Guo, Yun,Guo, Yanglong,Lu, Guanzhong,Wang, Yanqin
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- Synthesis of protected α-amino acids: Via decarboxylation amination from malonate derivatives
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A general and efficient strategy for the synthesis of protected α-amino acids is reported. The method uses malonate derivatives as the starting materials and Cs2CO3 as a base at 60 degrees, giving α-amino acid derivatives in moderate yields by releasing CO2. This methodology shows broad substrate scope (primary and secondary acids), excellent functional group tolerance and high efficiency to give the desired products under mild reaction conditions. It also allows the construction of β and γ-amino acids and other unnatural products.
- Dai, Qipu,Fu, Hui,Hu, Changwen,Li, Peihe,Li, Xiaoying,Wang, Zheng
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- Towards a bio-based industry: Benign catalytic esterifications of succinic acid in the presence of water
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The biorefinery of the future will need to integrate bioconversion and appropriate low environmental impact chemical technologies (Green Chemistry) so as to produce a wide range of products from biomass in an economically effective and environmentally acceptable manner. The challenge for chemists is to develop chemistry that works with fermentation-derived dilute, aqueous mixtures of oxygenated chemicals (platform molecules) rather than the petroleum-derived non-aqueous, non-oxygenated feedstocks we have been working with for 50+ years and to avoid energy intensive and wasteful concentration and purification steps. Here we show that a new family of tuneable mesoporous carbonaceous catalysts derived from starch can be used to accomplish efficient chemistry in aqueous solution. Our new aqueous catalytic chemistry relies on the ability to adjust the surface properties including the hydrophobicity-hydrophilicity balance of mesoporous Starbons by carbonisation at different temperatures (250-750°C). Simple treatment of these materials with sulfuric acid then provides a series of porous solid acids that can function under a range of conditions including dilute aqueous solution. The reactions of succinic acid (platform molecule) in aqueous alcohol demonstrate the outstanding activities of these new catalysts.
- Budarin, Vitaly,Luque, Rafael,Macquarrie, Duncan J.,Clark, James H.
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- Bis- and Tris(carboxylato)platinum(IV) Complexes with Mixed Am(m)ine Ligands in the trans Position Exhibiting Exceptionally High Cytotoxicity
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A series of seven diam(m)inebis(carboxylato)dihydroxidoplatinum(IV) and eleven diam(m)inetris(carboxylato)hydroxidoplatinum(IV) complexes with am(m)ine ligands in the trans position was synthesized and characterized by multinuclear 1H, 13C, 15N, 195Pt NMR spectroscopy. IC50 values for all eighteen substances were determined by means of the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay for three human cancer cell lines. In cisplatin-sensitive CH1(PA-1) cancer cells, diam(m)inebis(carboxylato)dihydroxidoplatinum(IV) complexes displayed 50 % inhibitory concentrations in the micromolar range, whereas for the most lipophilic compounds of the diam(m)inetris(carboxylato)hydroxidoplatinum(IV) series, promising IC50 values in the nanomolar range were found.
- Hoffmeister, Bj?rn R.,Hejl, Michaela,Jakupec, Michael A.,Galanski, Markus,Keppler, Bernhard K.
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- Pig liver esterase catalyzed hydrolyses of diesters. A new route to the syntheses of achiral half-esters
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Pig liver esterase catalyzed hydrolyses of diesters of alkanes, aromatic and heterocyclic compounds gave high yields of the corresponding half-esters under mild reaction conditions.
- Ager,Prakash
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- Kanglexin, a new anthraquinone compound, attenuates lipid accumulation by activating the AMPK/SREBP-2/PCSK9/LDLR signalling pathway
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Hyperlipidaemia is one of the major risk factors for atherosclerosis, coronary heart disease, stroke and diabetes. In the present study, we synthesized a new anthraquinone compound, 1,8-dihydroxy-3-succinic acid monoethyl ester-6-methylanthraquinone, and named it Kanglexin (KLX). The aim of this study was to evaluate whether KLX has a lipid-lowering effect and to explore the potential molecular mechanism. In this study, Sprague-Dawley rats were fed a high fat diet (HFD) for 5 weeks to establish a hyperlipidaemia model; then, the rats were orally administered KLX (20, 40, and 80 mg kg?1·d?1) or atorvastatin calcium (AT, 10 mg kg?1·d?1) once a day for 2 weeks. KLX had prominent effects on reducing blood lipids, hepatic lipid accumulation, body weight and the ratio of liver weight/body weight. Furthermore, KLXdramatically reduced the total cholesterol (TC) and triglyceride (TG) levels and lipid accumulation in a HepG2 cell model of dyslipidaemia induced by 1 mmol/L oleic acid (OA). KLX may decrease lipid levels by phosphorylating adenosine monophosphate-activated protein kinase (AMPK) and the downstream sterol regulatory element binding protein 2 (SREBP-2)/proprotein convertase subtilisin/kexin type 9 (PCSK9)/low-density lipoprotein receptor (LDLR) signalling pathway in the HFD rats and OA-treated HepG2 cells. The effects of KLX on the AMPK/SREBP-2/PCSK9/LDLR signalling pathway were abolished when AMPK was inhibited by compound C (a specific AMPK inhibitor) in HepG2 cells. In summary, KLX has an efficient lipid-lowering effect mediated by activation of the AMPK/SREBP-2/PCSK9/LDLR signalling pathway. Our findings may provide new insight into and evidence for the discovery of a new lipid-lowering drug for the prevention and treatment of hyperlipidaemia, fatty liver, and cardiovascular disease in the clinic.
- Li, Xin,Hu, Xueling,Pan, Tengfei,Dong, Lei,Ding, Lili,Wang, Zhenzhong,Song, Rui,Wang, Xiuzhu,Wang, Ning,Zhang, Yan,Wang, Jinhui,Yang, Baofeng
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- COMPOSITIONS AND METHODS FOR TREATING MORPHINE, HEROIN, AND ALCOHOL DEPENDENCE
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This invention provides a composition of matter comprising a plurality of morphine-6-succinyl-BSA, wherein the average ratio of morphine-6-succinyl moieties to BSA is at least 7.0. This invention also provides a composition of matter comprising a plurality of heroin-6-succinyl-BSA, wherein the average ratio of heroin-6-succinyl moieties to BSA is at least 7.0. This invention further provides a composition of matter comprising a plurality of ethanol-succinyl-BSA, wherein the average ratio of ethanol-succinyl moieties to BSA is at least 7.0. This invention still further provides related pharmaceutical compositions, therapeutic methods, prophylactic methods, synthetic methods, and articles of manufacture.
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Page/Page column 8; 33
(2021/12/08)
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- Zeolite Y from kaolin clay of Kachchh, India: Synthesis, characterization and catalytic application
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Kaolin clay obtained from Kachchh, Gujarat was used as alumina and silica source to synthesize zeolite Y by hydrothermal method. The synthesis route comprised of the following steps: sulfuric acid treatment at 110 ?°C (4 ?h) for impurity removal followed by calcination at 600 ?°C for 4 ?h, thermal activation of kaolin into metakaolin by NaOH fusion at 850 ?°C (8 ?h); aging of reaction mixtures at 50 ?°C (24 ?h); crystallization (24 ?h) followed by washing and drying. The synthesized zeolite Y was examined by multiple characterization techniques which revealed a pore volume of 0.22 ?cm3/g with pore size of 2.89 ?nm having essential surface area of 320 ?m2/g, indicating a porous material having majority of micropores and remaining mesopores. The zeolite exhibited good catalytic activity for succinic acid esterification using ethanol to produce monoethyl and diethyl succinate. The conversion of SA (72%) and yield (60%) of valuable diester indicated good conversion rate and selectivity at moderate reaction conditions. Detailed structural comparison with zeolite Y synthesized using standard chemical route is also carried out. This work demonstrated an effective way of preparing environmentally benign porous zeolite Y having high surface area and pore volume that can be useful for catalytic applications.
- Gandhi, Dolly,Bandyopadhyay, Rajib,Soni, Bhavna
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- Synthesis, characterization, lipophilicity and cytotoxic properties of novel bis(carboxylato)oxalatobis(1-propylamine)platinum(IV) complexes
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A series of novel bis(carboxylato)oxalatobis(1-propylamine)platinum(IV) complexes as well as an ethylamine analog were synthesized. The compounds are either symmetrical with both axial ligands consisting of monoesters of succinic acid, or unsymmetrical, with one axial ligand being acetate. The compounds were characterized in detail by elemental analysis, mass spectrometry and multinuclear (1H, 13C, 15N, 195Pt) NMR spectroscopy. The reduction behavior was followed by NMR spectroscopy, while lipophilicity was determined by analytical reversed-phase HPLC measurements. The capacity of inhibiting proliferation of the human cancer cell lines A549 (non-small cell lung cancer), CH1(PA-1) (ovarian teratocarcinoma) and SW480 (colon carcinoma) was evaluated by the MTT assay. In the most sensitive cell line CH1(PA-1), all compounds exhibited IC50 values in the lower μM range. In general, the IC50 values decreased with increasing lipophilicity within the two compound series. Nevertheless, replacing one of the succinic ester ligands with acetate has a rather marginal impact on antiproliferative activity and is hardly disadvantageous.
- Hizal, Selin,Hejl, Michaela,Jakupec, Michael A.,Galanski, Markus,Keppler, Bernhard K.
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- DRUGS AND COMPOSITIONS FOR OCULAR DELIVERY
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New prodrugs of therapeutically active compounds, including oligomeric prodrugs of ethacrynic acid, and compositions to treat medical disorders, for example glaucoma, a disorder or abnormality related to an increase in intraocular pressure (IOP), a disorder requiring neuroprotection, age-related macular degeneration, or diabetic retinopathy. Also a method for the controlled administration of timolol to a patient in need thereof, such as a human, comprising administering a prodrug of timolol in a microparticle in vivo, wherein the timolol prodrug containing microparticle exhibits in vitro drug release kinetics in an aqueous solution at a pH between 6-8 at body temperature of a substantially consistent release of at least 60% timolol itself by molar ratio to the prodrug of timolol or an intermediate metabolite thereof over at least 100 days.
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Page/Page column 160; 161
(2019/07/19)
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- Aloe-emodin succinyl ester compound with anti-inflammatory activity, and preparation method and application thereof
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The invention discloses an aloe-emodin succinyl ester compound with anti-inflammatory activity, and a preparation method and application thereof. The structural formula of the aloe-emodin succinyl ester compound is shown in a formula I. Research shows that the compound provided by the invention can inhibit occurrence of acute, subacute and immune inflammation, and the treatment effect is safe andeffective. Therefore, the provided aloe-emodin succinyl ester compound with the anti-inflammatory effect has an important application value in research and development of anti-inflammatory drugs.
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Paragraph 0054-0058
(2019/12/25)
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- Electrochemical cross-coupling of biogenic di-acids for sustainable fuel production
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Direct electrocatalytic conversion of bio-derivable acids represents a promising technique for the production of value-added chemicals and tailor-made fuels from lignocellulosic biomass. In the present contribution, we report the electrochemical decarboxylation and cross-coupling of ethyl hydrogen succinate, methyl hydrogen methylsuccinate and methylhexanoic acid with isovaleric acid. The reactions were performed in aqueous solutions or methanol at ambient temperatures, following the principles of green chemistry. High conversions of the starting materials have been obtained with maximum yields between 42 and 61% towards the desired branched alkane products. Besides costly Pt electrodes also (RuxTi1-x)O2 on Ti electrodes exhibited a notable activity for cross-Kolbe electrolysis. As some of the products are insoluble in water, easy product isolation and reuse of the reaction solvent is enabled via phase separation. Several side products have been identified to evaluate the efficiency of the reaction and to elucidate the factors influencing the product selectivity. The yielded alkanes and esters were assessed with regard to their potential as fuels for internal combustion engines. While the longer alkanes constitute promising candidates for the compression-ignition engine, the smaller ester represents an interesting option for the spark-ignition engine.
- Holzh?user, F. Joschka,Creusen, Guido,Moos, Gilles,Dahmen, Manuel,K?nig, Andrea,Artz, Jens,Palkovits, Stefan,Palkovits, Regina
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p. 2334 - 2344
(2019/05/21)
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- DRUGS AND COMPOSITIONS FOR THE TREATMENT OF OCULAR DISORDERS
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The present invention provides new prodrugs of therapeutically active compounds, including oligomeric prodrugs, and compositions to treat medical disorders, for example glaucoma, a disorder or abnormality related to an increase in intraocular pressure (IOP), a disorder requiring neuroprotection, age-related macular degeneration, or diabetic retinopathy.
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Page/Page column 245; 382
(2018/10/19)
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- The emodin succinyl ester compounds in the preparation of pharmaceutical use in fat
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The invention discloses emodin succinyl ester compounds in the preparation of the use of the drug in the blood, which belongs to the field of medical technology, the emodin succinyl ester compound of the structure shown in formula I (R is C1 - 5 Alkyl). The experiment mixed hyperlipidemia rats pharmacological experiment, confirms that the emodin succinyl ester compound is superior to the emodin, with hypolipidemic effects are prominent, good safety, administration is simple and convenient, cheap price of raw materials are easy, convenient transportation and storage advantages. The invention of the proposed emodin succinyl ester compound in the blood lipid-lowering medicine preparation field will have broad application prospects.
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Paragraph 0055; 0063; 0069
(2018/07/30)
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- COALESCING AGENT DERIVED FROM SUCCINATE ESTER
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The present invention relates to a coalescing agent and a coating composition containing the coalescing agent as represented in structure (I); [Formula should be inserted here] wherein; n is integer from 1 to 8; R1 and R2 independently represents group selected from alkyl, alkenyl, alkynyl, phenyl, or benzyl groups; and X represents group selected from hydroxy or amine. The coalescing agent according to this invention contains low amount of volatile organic compounds, has no pungent odour, and environmental friendly. Moreover, it provides good efficacy when being used as coating component.
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Page/Page column 6; 7
(2017/11/04)
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- DEOXYDEHYDRATION OF SUGAR DERIVATIVES
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The disclosure provides methods for deoxydehydration of sugar-based derivatives using hydrogen gas as a reducing agent.
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Paragraph 0134; 0135; 0136
(2017/09/09)
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- Intermediate for standard auspicious Luo river (1R, 2S) - 2 - (2,3-difluorophenyl) method for the preparation of cyclopropylamines (by machine translation)
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The invention discloses a method for preparing ticagrelor midbody (1R,2S)-2-(2,3-difluorophenyl) cyclopropylamine, belonging to the technical fields of organic synthesis route design and preparation of raw material medicines and midbodies. The method comprises the following steps: performing alcoholysis on succinic anhydride, thereby obtaining mono-methyl succinate, performing acylating chlorination reaction on mono-methyl succinate, thereby obtaining a compound methyl 4-chloro-4-oxobutyrate, performing Fridel-Crafts reaction on methyl 4-chloro-4-oxobutyrate and o-difluorobenzene, thereby obtaining a compound methyl 4-ketone-4-(3,4-difluorophenyl) butyrate (IV), and further performing asymmetric reduction reaction, cyclization reaction and Hoffman degradation on the compound IV, thereby obtaining the compound (1R,2S)-2-(2,3-difluorophenyl) cyclopropylamine. Initial raw materials used in the method are low in cost and easy to obtain, the reaction condition is gentle, the operation is safe, simple and convenient, the environment pollution is small, and the key ticagrelor midbody prepared by using the method is simple and convenient in after treatment, and is beneficial to on-scale production.
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Paragraph 0038; 0039
(2017/03/23)
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- COMPOUND FOR PROMOTING APOPTOSIS OF CANCER CELLS AND A PHARMACEUTICAL COMPOSITION CONTAINING THE SAME AND USES THEREOF
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The present invention provides a compound of Formula (I) and a salt thereof, wherein, m is an integer of 2 to 7, and R is independently at least one selected from the group consisting of hydrogen and C1-C20 alkyl. The compound promotes apoptosis in cancer cell and inhibits its growth. The present invention also provides a pharmaceutical composition which comprises the compound of Formula (I), a salt thereof and a pharmaceutically acceptable carrier. The present invention further provides a method for production of the pharmaceutical composition used for treating cancer.
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Paragraph 0086
(2016/04/20)
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- Optimization of gefitinib analogues with potent anticancer activity
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The interactions of gefitinib (Iressa) in EGFR are hydrogen bonding and van der Waals forces through quinazoline and aniline rings. However the morpholino group of gefitinib is poorly ordered due to its weak electron density. A series of novel piperazino analogues of gefitinib where morpholino group substituted with various piperazino groups were designed and synthesized. Most of them indicated significant anti-cancer activities against human cancer cell lines. In particular, compounds 52-54 showed excellent potency against cancer cells. Convergent synthetic approach has been developed for the synthesis of gefitinib intermediate which can lead to gefitinib as well as numerous analogues.
- Yin, Kai-Hao,Hsieh, Yi-Han,Sulake, Rohidas S.,Wang, Su-Pei,Chao, Jui-I.,Chen, Chinpiao
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supporting information
p. 5247 - 5250
(2015/01/08)
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- Synthesis of monoesters and diesters using eco-friendly solid acid catalysts - Cerium(IV) and thorium(IV) phosphates
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In the present endeavour, amorphous cerium phosphate (CP) and thorium phosphate (TP) have been synthesized by sol-gel method and also under microwave irradiation to yield CPM and TPM. CP, TP, CPM and TPM have been characterized for elemental analysis (ICP-AES), spectral analysis (FTIR), thermal analysis (TGA), X-ray diffraction studies, SEM, EDX, surface area (BET) and surface acidity (NH3-TPD). The potential use of these materials as solid acid catalysts has been explored by studying esterification as a model reaction. Monoesters such as ethyl acetate (EA), propyl acetate (PA), butyl acetate (BA), benzyl acetate (BzAc) and diesters such as diethyl malonate (DEM), diethyl succinate (DES), dibutyl phthalate (DBP), dioctyl phthalate (DOP) have been synthesized. Esterification conditions have been optimized by varying several parameters such as reaction time, catalyst amount and mole ratio of reagents. The catalytic activity has been compared and correlated with reference to surface acidity of the catalysts. It is found that catalytic activity of CPM > CP > TP M > TP. The regenerated catalysts could be reused upto two catalytic runs without significant loss in % yields of esters formed. The highlighting feature of the present work is the catalysts CPM and TPM that are synthesized in a much shorter reaction time with higher surface acidity giving good % yield of esters.
- Parangi, Tarun,Wani, Bina,Chudasama, Uma
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p. 430 - 438
(2013/09/23)
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- CARBOXYLIC ACID RECOVERY AND METHODS RELATED THERETO
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A method of producing an alkyl ester of a carboxylic acid is provided, the method comprising: adding an alkanol and a mineral acid to a carboxylic acid salt to provide a carboxylic acid/alkanol solution and a precipitated mineral acid salt; separating the mineral acid salt from the carboxylic acid/alkanol solution; esterifying the carboxylic acid; and isolating an alkyl ester of the carboxylic acid.
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Page/Page column 23-26
(2011/06/25)
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- An efficient enzymatic preparation of 20-pregnane succinates: chemoenzymatic synthesis of 20β-hemisuccinyloxy-5αH-pregnan-3-one
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Lipase-catalyzed transesterification of the 20 hydroxyl group in a series of pregnanes afforded novel 20-ethyl succinates that are not possible to prepare following the traditional synthetic methods. The reaction is stereoselective. The enzyme reacts selectively with the 20β epimers therefore only the 20β-succinyloxy derivatives are obtained. These compounds are obtained in variable yield, depending on the substitution in the ring A. The enzymatic approach allowed, for the first time, the synthesis of 20β-hemisuccinyloxy-5αH-pregnan-3-one, novel compound useful as a precursor of steroid-protein conjugates.
- Monsalve, Leandro N.,Machado Rada, Mayra Y.,Ghini, Alberto A.,Baldessari, Alicia
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p. 1721 - 1730
(2008/09/19)
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- Synthesis and anti-cancer activity of C-ring-functionalized prodigiosin analogues
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Prodigiosin is the parent member of the 4-methoxypyrrolyldipyrromethene family of natural products and is known for its anti-cancer activity. A new series of analogues was synthesized, incorporating pendent functional esters and β-carbonyl substituents on the C-ring. The β-carbonyl group allowed for the facile isolation of the prodigiosenes, and the pendent esters allow for further derivatization. The novel prodigiosenes generally retain the anti-cancer activity of prodigiosin in 60 human cell lines derived from nine cancer cell types, with neither the conjugated /3-carbonyl group, as either ketone or ester, nor the pendent ester significantly reducing the anti-cancer activity of the core skeleton.
- Regourd, Jasmine,Ali, Adeeb Al-Sheikh,Thompson, Alison
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p. 1528 - 1536
(2008/02/02)
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- Process for reactive esterification distillation
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A process for producing organic acid di- or tri-esters, particularly citric acid tri-esters, with the available acid groups esterified using countercurrent reactive distillation using acid catalysts in a structured packing is described. In the reactive distillation an organic acid di- or triester is formed by chemical reaction and purified to its final state within the single column. Organic acid di- or tri-esters are produced at relatively low cost, with less waste production in by-products of the reaction, and in a less complicated manner than prior processes. Organic acid di- and tri-esters have uses as solvents, as plasticizers and in conversion products.
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Page/Page column 22; 91
(2008/06/13)
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- Regio- and stereoselectivity in the titanium-mediated cyclopropanation of ω-alkenoic diesters: Application in the diastereoselective synthesis of pyrrolidinone
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The titanium-mediated intramolecular cyclopropanation of ω-allylic succinates leads only to cyclopropanol, arising from exclusive reactivity of one ester function. As an extension of this methodology, the diastereoselective synthesis of highly functionalized pyrrolidinone has been realized from cheap commercially available L-aspartic acid. Georg Thieme Verlag Stuttgart.
- Garnier, Jean-Marc,Jida, Mouhamad,Ollivier, Jean
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p. 2739 - 2742
(2008/02/11)
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- Direct oxidative cleavage of α- and β-dicarbonyls and α-hydroxyketones to diesters with KHSO5
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Presented is a methodology to oxidatively cleave α-hydroxyketones and α- or β-diones using the environmentally benign reagent KHSO 5, prepared easily from Oxone, to diesters in one simple transformation. In addition, we undertook a mechanistic study to provide a plausible mechanistic interpretation. These reactions may prove to be valuable alternatives to other related metal-mediated processes.
- Yan, Jun,Travis, Benjamin R.,Borhan, Babak
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p. 9299 - 9302
(2007/10/03)
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- A ribozyme with michaelase activity: synthesis of the substrate precursors.
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The ability to generate RNA molecules that can catalyze complex organic transformations not only facilitates the reconstruction and plausibility of possible prebiotic reaction pathways but is also crucial for elucidating the potential of the application of RNA catalysts in organic syntheses. Iterative RNA selection previously identified a ribozyme that catalyzes the Michael addition of a cysteine thiol to an alpha,beta-unsaturated amide. This reaction is chemically similar to the rate limiting step of the thymidylate synthase reaction, which is the corresponding reaction of a cysteine thiol to the double-bond of the uracil nucleobase. Here we provide a detailed description of the synthesis of the ribozyme substrates and the substrate oligonucleotides used for its characterization and the investigation of the background reaction. We also describe the further characterization of the ribozyme with respect to substrate specificity. We show that the thiol group of the cysteine nucleophile is essential for the reaction to proceed. When substituted for a thiomethyl group, no reaction takes place.
- Eisenfuehr, Alexander,Arora, Paramjit S,Sengle, Gerhard,Takaoka, Leo R,Nowick, James S,Famulok, Michael
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p. 235 - 249
(2007/10/03)
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- A combination of Friedel-Crafts and Lawesson reactions to 5-substituted 2,2′-bithiophenes
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γ-Keto esters (2) derivatives of thiophene were obtained from hemisuccinic esters and transformed to the corresponding amides (4). Lawesson's treatment of 2 and 4 gave the corresponding bithiophenes (5) with alkoxy or amino substituents.
- Raposo, M. Manuela M.,Kirsch
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p. 1487 - 1498
(2007/10/03)
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- Ring opening of cyclic anhydrides: Synthesis of achiral half-esters using Lewis acids
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A rapid and high yield preparation of half-esters from cyclic anhydrides using alcohols and Lewis acids is described.
- Sabitha, Gowravaram,Srividya,Yadav
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p. 4015 - 4018
(2007/10/03)
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- Arylmethyl esters as protecting groups for carboxylic, carbonic and carbamic acids: Deprotection via homogeneous palladium-catalyzed hydrogenolysis
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4-Quinolylmethyl (4-QUI) esters of carboxylic acids and 1-naphthylmethyl (1-NAP) esters of carbonic and carbamic acids are reduced by palladium-catalyzed hydrogenolysis by formate anion. The reaction conditions are compatible with the presence of a benzyl ester and of an alkene double bond.
- Boutros, Andre,Legros, Jean-Yves,Fiaud, Jean-Claude
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p. 7329 - 7332
(2007/10/03)
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- Synthesis and investigation of N4-substituted cytarabine derivatives as prodrugs.
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Esters of Cytarabine-N4-carboxylates 2a-i and succinamates 3a-f were synthesized as prodrugs of cytarabine (Ara-C) with the aim of developing improved derivatives for oral or parentral administration. At pH 2 series 2 showed relative higher stability than 3, while both series of esters revealed matched stability at pH 7. All esters were susceptible to enzymatic hydrolysis by rat plasma and liver homogenate with half lives ranged from 0.14 h to 12 d, and showed improved stability against cytidine deaminase. A parabolic relation was shown between Kobs of enzymatic hydrolysis and Vw. All compounds are more lipophilic than the parent drug, Ara-C.
- Fadl,Hasegawa,Youssef,Farag,Omar,Kawaguchi
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p. 382 - 387
(2007/10/02)
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- Phyllanthoside-Phyllanthostatin Synthetic Studies. 7. Total Synthesis of (+)-Phyllanthocin and (+)-Phyllanthocindiol
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A stereochemically linear total synthesis of (+)-phyllanthocin (5a), the aglycon methyl ester of the antineoplastic glycoside (+)-phyllanthoside (1), is described. The synthesis proceeds in 23 steps (4.5% overall yield) and affords (+)-phyllanthocin in high enantiomeric purity. The central features of the strategy include: (a) construction of aldehyde 8 via a stereoselective, intramolecular ene reaction; (b) elaboration of the spiroketal unit by a two-step tactic involving addition of a functionalized dihydropyran anion (i.e., 9) to 8, followed by a highly stereoselective spiroketalization; and (c) chemo- and stereoselective methylenation of the C(7) carbonyl group. In addition, a second-generation approach is presented, wherein an augmented spiroketalization maneuver not only establishes the C(8) spirocenter but also permits the regio- and stereocontrolled introduction of the C(11) methyl group. The latter sequence furnishes (+)-phyllanthocin in 21 steps (5.6% overall yield). Finally, the advanced phyllanthocin intermediate (+)-49 is converted in five steps (42% overall yield) to (+)-phyllanthocindiol (5b), the aglycon of phyllanthostatin 3.
- Smith III, Amos B.,Fukui, Mineo,Vaccaro, Henry A.,Empfield, James R.
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p. 2071 - 2092
(2007/10/02)
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- NOUVEAUX DECONTAMINANTS. ACTION DES PERACIDES A GROUPE ESTER SUR QUELQUES TOXIQUES INSECTICIDES OU DE GUERRE
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A new peroxyacid-ester series has been obtained and used in the destruction of toxic agents.These structures oROCOC6H4CO3H and ROCO(CH2)nCO3H are more stable than the unsubstituted compounds.The reaction with paraoxon (O,O-diethyl O-paranitrophenylphosphate) and HD (2,2'-dichlorodiethylsulfide) goes to completion in a very short time.The influence of the R group and the length of the chain (n=2......12) has been studied.The addition of some long chain tetraalkyl-ammonium salts enhances the rate of the reaction by micellar catalysis.
- Lion, C.,Hedayatullah, M.,Bauer, P.,Boukou-Poba, J. P.,Charvy, C.,et al.
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p. 555 - 560
(2007/10/02)
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- Acetazolamide-related compounds, process for their preparation, and pharmaceutical composition containing the same
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Compounds related to acetazolamide and to its N-methyl derivatives, of the formulae: STR1 wherein Y is one of the following groups: STR2 R1 being a straight or branched alkylene or arylalkylene, or a phenylene, and the processes for their preparation; the compounds so obtained are inhibitors of carbonic anhydrase like acetazolamide but, in addition, they are well absorbed topically so that they can be used as drugs for treating glaucoma.
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- High- and Low-Potential Flavin Mimics. 3. 3,7,10-Trimethyl-(1H,3H,5H,7H,9H,10H)-pyrimidopteridine-2,4,6,8-tetrone-Mediated Reduction of Carbon-Carbon Double Bond α-β to an Acyl Function
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The reduction of the carbon-carbon double bond of maleimide (MI), N-methylmaleimide (NMM), ethyl fumarate, diethyl fumarate, diethyl maleate, fumaric acid, and maleic acid was investigated by employing the low redox potential flavin mimic 3,7,10-trimethyl-(1H,3H,5H,7H,9H,10H)-pyrimidopteridine-2,4,6,8-tetrone (PPTH2) as the reductant.The reaction of these substrates with PPTH2 to produce PPTox and the corresponding succinimide or succinate consists of three processes.The first process occurs on mixing and pertains to the formation of a mixture of N(1)- and C(4a)-substrate adducts of PPTH2.The other two processes, which are kinetically distinguishable, pertain to the breakdown of each of these adducts to PPTox and the reduced substrate.Breakdown of the C(4a)-adduct is catalyzed by hydroxide and is independent of substrate concentration.Hydroxide catalysis is proposed to represent a concerted process whereby the hydroxide abstracts the N(5)-proton while the anionic reduced substrate is departing (Bronsted β approaching 1.0).Breakdown of the N(1)-adduct to the observed products is substrate-dependent pertaining to the rate-determining formation of the N(9),C(4a)-diadduct.In a fast step, base-catalyzed elimination from the C(4a)-position of the latter provides the reduced substrate anion and the N(9)-monosubstrate adduct of PPTox.Rapid dissociation of the N(9)-adduct then provides PPTox.It is concluded that the reduction of a carbon-carbon double bond to an acyl function by the low-potential flavin mimic proceeds via C(4a)-adducts.This conclusion and the principle of microreversibility infers that enzyme-bound flavins of high potential, as in dehydrogenating flavoenzymes, may oxidize succinates to fumarates via C(4a)-adducts.
- Skibo, Edward B.,Bruice, Thomas C.
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p. 1650 - 1659
(2007/10/02)
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- CARBOXY AND SUBSTITUTED CARBOXY ALKANOYL AND CYCLOALKANOYL PEPTIDES
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Peptides of the formula STR1 wherein X is various amino or imino acids or esters are useful as hypotensive agents.
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