- New compounds for a good old class: Synthesis of two Β-lactam bearing cephalosporins and their evaluation with a multidisciplinary approach
-
Antimicrobial resistance is spreading massively in the world and is becoming one of the main health threats of the 21st century. One of the possible strategies to overcome this problem is to modify the known classes of antibiotics in a rational way, with the aim of tuning their efficacy. In this paper, we present the synthesis and the evaluation of the biological activity of a series of two β-lactam bearing cephalosporin derivatives, in which an additional isolated azetidinone ring, bearing different substituents, is joined to the classical cephalosporanic nucleus by a chain of variable length. A computational approach has been also applied in order to predict the molecular interactions between some representative derivatives and selected penicillin-binding proteins, the natural targets of β-lactam antibiotics. All these derivatives are active against Gram-positive bacteria, with MIC100 comparable or even better than that of the reference antibiotic ceftriaxone, and show no or very low cytotoxic activity on different cell lines. Overall, these molecules appear to be able to exert their activity in particular against microorganisms belonging to some of the species more involved in the development of multidrug resistance.
- Vigliotta, Giovanni,Giordano, Deborah,Verdino, Anna,Caputo, Ivana,Martucciello, Stefania,Soriente, Annunziata,Marabotti, Anna,De Rosa, Margherita
-
supporting information
(2020/01/22)
-
- PYRIDAZINE DERIVATIVES AS SMARCA2/4 DEGRADERS
-
The present invention provides pyridazine derivatives of formula (I), which are therapeutically useful as SMARCA2/4 degraders. These compounds are useful in the treatment and/or prevention of diseases or disorders dependent upon SMARCA2/4 in a mammal. The present invention also provides preparation of the compounds and pharmaceutical compositions comprising at least one of the pyridazine derivatives of formula (I) or a pharmaceutically acceptable salt, or a stereoisomer thereof.
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Page/Page column 91-92
(2019/11/12)
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- Novel photochemical reactions of carbocyclic diazodiketones without elimination of nitrogen – a suitable way to N-hydrazonation of C–H-bonds
-
The sensitized photoexcitation of 2-diazocyclopentane-1,3-diones in the presence of THF leads to the insertion of the terminal N-atom of the diazo group into the α-С–Н bond of THF, producing the associated N-alkylhydrazones in yields of up to 63–71%. Further irradiation of hydrazones derived from furan-fused tricyclic diazocyclopentanediones culminates in the cycloelimination of furans to yield 2-N-(alkyl)hydrazone of cyclopentene-1,2,3-trione. By contrast, the direct photolysis of carbocyclic diazodiketones gives only Wolff rearrangement products with up to 90–97% yield.
- Rodina, Liudmila L.,Azarova, Xenia V.,Medvedev, Jury J.,Semenok, Dmitrij V.,Nikolaev, Valerij A.
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p. 2250 - 2258
(2018/09/14)
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- Intracellular delivery of chemical probes using a glutathione-responsive traceless tag
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A new glutathione (GSH)-responsive traceless tag that facilitates intracellular delivery of small molecule chemical probes has been developed.
- Aoyama, Eriko,Fuchida, Hirokazu,Oshikawa, Yuji,Uchinomiya, Shohei,Ojida, Akio
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supporting information
p. 7715 - 7718
(2016/07/06)
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- Computer-aided identification of new histone deacetylase 6 selective inhibitor with anti-sepsis activity
-
Histone deacetylase (HDAC) inhibitors have been recognized as promising approaches to the treatment of various human diseases including cancer, inflammation, neurodegenerative diseases, and metabolic disorders. Several pan-HDAC inhibitors are currently approved only as anticancer drugs. Interestingly, SAHA (vorinostat), one of clinically available pan-HDAC inhibitors, shows an anti-inflammatory effect at concentrations lower than those required for inhibition of tumor cell growth. It was also reported that HDAC6 selective inhibitor tubastatin A has anti-inflammatory and anti-rheumatic effect. In our efforts to develop novel HDAC inhibitors, we rationally designed various HDAC inhibitors based on the structures of two hit compounds identified by virtual screening of chemical database. Among them, 9a ((E)-N-hydroxy-4-(2-styrylthiazol-4-yl)butanamide) was identified as a HDAC6 selective inhibitor (IC50 values of 0.199 μM for HDAC6 versus 13.8 μM for HDAC1), and it did not show significant cytotoxicity against HeLa cells. In vivo biological evaluation of 9a was conducted on a lipopolysaccharide (LPS)-induced mouse model of sepsis. The compound 9a significantly improved 40% survival rate (P = 0.0483), and suppressed the LPS-induced increase of TNF-α and IL-6 mRNA expression in the liver of mice. Our study identified novel HDAC6 selective inhibitor 9a, which may serve as a potential lead for the development of anti-inflammatory or anti-sepsis agents.
- Yoo, Jakyung,Kim, So-Jin,Son, Dohyun,Seo, Heewon,Baek, Seung Yeop,Maeng, Cheol-Young,Lee, Changsik,Kim, In Su,Jung, Young Hoon,Lee, Sun-Mee,Park, Hyun-Ju
-
p. 126 - 135
(2016/04/19)
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- NMR-based molecular ruler for determining the depth of intercalants within the lipid bilayer. Part III: Studies on keto esters and acids
-
The development of "molecular rulers" would allow one to quantitatively locate the penetration depth of intercalants within lipid bilayers. To this end, an attempt was made to correlate the 13C NMR chemical shift of polarizable "reporter" carbons (e.g., carbonyls) of intercalants within DMPC liposomal bilayers - with the polarity it experiences, and with its Angstrom distance from the interface. This requires families of molecules with two "reporter carbons" separated by a known distance, residing at various depths/polarities within the bilayer. For this purpose, two homologous series of dicarbonyl compounds, methyl n-oxooctadecanoates and the corresponding n-oxooctadecanoic acids (n = 4-16), were synthesized. To assist in assignment and detection several homologs in each system were prepared 13C-enriched in both carbonyls. Within each family, the number of carbons and functional groups remains the same, with the only difference being the location of the second ketone carbonyl along the fatty acid chain. Surprisingly, the head groups within each family are not anchored near the lipid-water interface, nor are they even all located at the same depth. Nevertheless, using an iterative best fit analysis of the data points enables one to obtain an exponential curve. The latter gives substantial insight into the correlation between polarity (measured in terms of the Reichardt polarity parameter, ET(30)) and penetration depth into the liposomal bilayer. Still missing from this curve are data points in the moderate polarity range.
- Afri, Michal,Alexenberg, Carmit,Aped, Pinchas,Bodner, Efrat,Cohen, Sarit,Ejgenburg, Michal,Eliyahu, Shlomi,Gilinsky-Sharon, Pessia,Harel, Yifat,Naqqash, Miriam E.,Porat, Hani,Ranz, Ayala,Frimer, Aryeh A.
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p. 105 - 118
(2015/02/19)
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- Insights into soluble guanylyl cyclase activation derived from improved heme-mimetics
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Recently, the structure of BAY 58-2667 bound to the Nostoc sp. H-NOX domain was published. On the basis of this structural information, we designed BAY 58-2667 derivatives and tested their effects on soluble guanylyl cyclase (sGC) activity. Derivative 20 activated sGC 4.8-fold more than BAY 58-2667. Co-crystallization of 20 with the Ns H-NOX domain revealed that the increased conformational distortion at the C-terminal region of αF helix containing 110-114 residues contributes to the higher activation triggered by 20.
- Von Wantoch Rekowski, Margarete,Kumar, Vijay,Zhou, Zongmin,Moschner, Johann,Marazioti, Antonia,Bantzi, Marina,Spyroulias, Georgios A.,Van Den Akker, Focco,Giannis, Athanassios,Papapetropoulos, Andreas
-
supporting information
p. 8948 - 8952
(2013/12/04)
-
- Design, synthesis and preliminary bioactivity studies of 1,3,4-thiadiazole hydroxamic acid derivatives as novel histone deacetylase inhibitors
-
Histone deacetylase (HDAC) inhibitors have emerged as a new class of anticancer agents, targeting the biological processes including cell cycle, apoptosis and differentiation. In the present study, a series of 1,3,4-thiadiazole based hydroxamic acids were developed as potent HDAC inhibitors. Some of them showed good inhibitory activity in HDAC enzyme assay and potent growth inhibition in some tumor cell lines. Among them, compound 6i (IC50 = 0.089 μM), exhibited better inhibitory effect compared with SAHA (IC50 = 0.15 μM).
- Guan, Peng,Sun, Feng'E,Hou, Xuben,Wang, Feng,Yi, Fan,Xu, Wenfang,Fang, Hao
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experimental part
p. 3865 - 3872
(2012/08/27)
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- INDAZOLE COMPOUNDS
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Indazole compounds, processes for their preparation, pharmaceutical compositions containing such compounds and their use in therapy.
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Page/Page column 29
(2012/03/26)
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- ESTERAMIDE SOLVENTS/COALESCING AGENTS IN PHYTOSANITARY, CLEANING, DEGREASING, STRIPPING, LUBRICATING, COATING, AND PIGMENT/INK COMPOSITIONS
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Esteramide compounds are useful solvents/coalescing agents for a variety of phytosanitary, cleaning, degreasing, stripping, lubricating, coating and pigment/ink compositions.
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Page/Page column 18
(2011/07/29)
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- Synthesis and biological evaluation of Ezetimibe analogs as possible cholesterol absorption inhibitors
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In order to investigate the SAR of Ezetimibe analogs for cholesterol absorption inhibitions, amide group and electron-deficient pyridine ring were introduced to the C-(3) carbon chain of Ezetimibe. Eight new derivatives of the 2- azetidinone cholesterol absorption inhibitors have been synthesized, and all of them were enantiomerically pure. All the new compounds were evaluated for their activity to inhibit cholesterol absorption in hamsters, and most of them showed comparable effects in lowering the levels of total cholesterol in the serum.
- Wang, Yubin,Haiqian,Huang, Wenlong,Zhang, Huibin,Zhou, Jinpei
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scheme or table
p. 500 - 505
(2012/05/19)
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- Product recovery from ionic liquids by solvent-resistant nanofiltration: Application to ozonation of acetals and methyl oleate
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In this work we tackle the problematic separation of reaction products from ionic liquid media. Solvent-resistant nanofiltration proves to be an attractive technique for the separation of non-volatile polar products from ionic liquids. In view of the high compatibility between ozone and ionic liquids, two ozone-mediated model reactions were chosen: firstly the oxidation of acetals to esters in the presence of ozone and secondly the ozonation of methyl oleate to monomethyl azelate and pelargonic acid. The objective was to retain the ionic liquid phase by means of a solvent-resistant nanofiltration membrane, while the organic reaction products permeate through the polymeric membrane. First, the ozonations were studied in order to know the characteristic product compositions. Next, a screening of membranes was performed on synthetic product mixtures. The second generation polyimide-based DuraMem membranes showed the highest rejection, up to 96%, for the evaluated ionic liquids. These DuraMem membranes also proved suitable for the separation of the products on real reaction mixtures, even in a single filtration step.
- Van Doorslaer, Charlie,Glas, Daan,Peeters, Annelies,Cano Odena, Angels,Vankelecom, Ivo,Binnemans, Koen,Mertens, Pascal,De Vos, Dirk
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experimental part
p. 1726 - 1733
(2011/02/22)
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- Oxidation of cyclic acetals by ozone in ionic liquid media
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The application of ozone-stable pyrrolidinium based ionic liquids as safe reaction media resulted in selective hydroxy ester formation upon ozonation of cyclic acetals without using low temperatures or acetylating reagents.
- Van Doorslaer, Charlie,Peeters, Annelies,Mertens, Pascal,Vinckier, Chris,Binnemans, Koen,De Vos, Dirk
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experimental part
p. 6439 - 6441
(2010/03/04)
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- 2-Azetidinone derivatives: Design, synthesis and evaluation of cholesterol absorption inhibitors
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Fourteen new derivatives of the 2-azetidinone cholesterol absorption inhibitors have been synthesized, and three of them were enantiomerically pure. All the new compounds were evaluated for their activity to inhibit cholesterol absorption in rats, and most of them showed comparable effects in lowering the levels of total cholesterol in the serum.
- Wang, Yubin,Zhang, Huibin,Huang, Wenlong,Kong, Jing,Zhou, Jinpei,Zhang, Beibei
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experimental part
p. 1638 - 1643
(2009/05/30)
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- IMPROVED PROCESS FOR THE PREPARATION OF EZETIMIBE AND ITS INTERMEDIATES
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The present invention provides an improved process for the preparation of ezetimibe through novel organic amine salt compounds of general formula (1). The present invention also relates to a highly pure ezetimibe and 3-((3R,4S)-1-(4-fluorophenyl)-2-oxo-4-(4-(benzyloxy)phenyl) azetidin-3-yl)propionic acid compound.
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Page/Page column 17
(2008/06/13)
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- SYNTHESIS OF HALF ESTERS
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A method for hydrolyzing an ester is provided. In accordance with the method, a compound A is provided which has first and second ester moieties. The compound is reacted in a liquid medium with a base having the formula MaXb,such that the first ester moiety is converted to a carboxyl moiety and the second ester moiety remains, wherein the ratio [Xk-]:[A] in the liquid medium is no greater than 1.6, and wherein k > 0.
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Page/Page column 27-28
(2009/01/24)
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- Clean and easy photochemistry
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In this paper we try to convince you that the usual prejudices against photochemistry are not always well founded, supported by examples from the literature and from our own work. In fact, photochemistry can be a very powerful tool, for example in some elegant total syntheses which use key photochemical steps. Furthermore, the exploitation of chromatic orthogonality which allows wavelength-selective reactions, and recent strategies opening the possibility of enantioselective catalysis in photochemical reactions, expand the scope of this versatile synthetic tool. Finally, state-of-art LED-technology has allowed the development of small and easy-to-use photoreactors. Schweizerische Chemische Gesellschaft.
- Ciana, Claire-Lise,Bochet, Christian G.
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p. 650 - 654
(2008/03/11)
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- A new method for constructing quaternary carbon centres: Tandem rhodium-catalysed 1,4-addition/intramolecular cyclisation
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The efficient tandem rhodium-catalysed 1,4-addition/cyclisation of 1,1′-alkenes using arylzinc chlorides is described. The simple one-step synthesis of substituted cyclopentanone and cyclohexanone derivatives is performed from acyclic precursors using relatively low catalyst loadings under mild conditions. A new quaternary carbon centre is created during the cyclisation step.
- Le Notre, Jerome,Van Mele, David,Frost, Christopher G.
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p. 432 - 440
(2008/02/07)
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- IMPROVED PROCESS FOR THE PREPARATION OF EZETIMIBE
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The present invention relates to a cost effective and industrially advantageous process for the preparation of (3R,4S)-l-(4-Fluorophenyl)-3-[3(S)-3-(4-fluorophenyl)-3 - hydroxypropyl)]-4-(4-hydroxyρhenyl)-2-azetidinone, referred to here as Ezetimibe, it is represented as formula (1).
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Page/Page column 11
(2008/06/13)
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- Traceless Staudinger ligation of glycosyl azides with triaryl phosphines: Stereoselective synthesis of glycosyl amides
-
α-Glycosyl amides can be synthesized from the corresponding O-benzyl-α-glycosyl azides using a traceless Staudinger ligation with diphenylphosphanyl-phenyl esters 4. All the phosphines employed and their phenol precursors are stable to air at 4 °C for months. Fast intramolecular trapping of the reduction intermediates results in the direct formation of the amide link, which, in turn, prevents epimerisation and allows retention of configuration at the anomeric carbon. Yields and α-selectivity are high when the reaction is performed in polar aprotic solvents. Removal of the benzyl ether protecting groups is achieved by catalytic hydrogenation. α-Glycosyl amides represent a class of virtually unexplored nonhydrolyzable monosaccharide derivatives that may find a useful application as sugar mimics. Conformational studies by NMR spectroscopy confirm that deprotected α-glycosyl amides in the gluco, galacto, and fuco series retain the normal pyranose conformation of the monosaccharide. The reaction of phosphines 4 with tetra-O-acetyl-glycosyl azides is nonstereoconservative, and β-glycosyl amides are obtained in good yields and with complete stereoselectivity starting from both α and β azides.
- Bianchi, Aldo,Bernardi, Anna
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p. 4565 - 4577
(2007/10/03)
-
- Effects of counter cations in selective monohydrolyses of symmetric diesters
-
Monohydrolyses of symmetric diesters were carried out using several aqueous inorganic bases, LiOH, NaOH, KOH, and CsOH. The more reactive bases showed higher selectivities in the monohydrolyses of acyclic symmetric diesters.
- Niwayama, Satomi,Rimkus, Audrius
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p. 498 - 500
(2007/10/03)
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- Inhibitors of cholesteryl ester transfer protein
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This invention relates to inhibitors of CETP and methods for producing these inhibitors. The invention also provides pharmaceutical compositions comprising the inhibitors of the invention and methods of utilizing the inhibitors and pharmaceutical compositions in the treatment and prevention of various disorders mediated by CETP.
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Page/Page column 28-29
(2010/02/15)
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- A possible improvement for structure-based drug design illustrated by the discovery of a Tat HIV-1 inhibitor
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The HIV-1 Tat protein is a promising target for AIDS therapy, due to its extra-cellular roles against the immune system. From the 2D-NMR structure of Tat, we have designed molecules, called TDS, able to bind to Tat and inhibit HIV-1 replication in vitro. This new family of antivirals is composed of a triphenylene aromatic ring substituted with at least one carbon chain bearing a succinimide group. These ligands are prepared from triphenylene or 2,6,10-trimethylphenylene in 3-6 steps depending on the target molecule.
- Montembault, Mickael,Vo-Thanh, Giang,Deyine, Abdallah,Fargeas, Valerie,Villieras, Monique,Adjou, Ane,Dubreuil, Didier,Esquieu, Didier,Gregoire, Catherine,Opi, Sandrine,Peloponese, Jean-Marie,Campbell, Grant,Watkins, Jennifer,De Mareuil, Jean,Aubertin, Anne-Marie,Bailly, Christian,Loret, Erwann,Lebreton, Jacques
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p. 1543 - 1546
(2007/10/03)
-
- Sequentially photocleavable protecting groups in solid-phase synthesis
-
(Matrix presented) A sequential solid-phase peptide synthesis was developed using both photolabile linker and protecting groups. The chromatic sequential lability between a tert-butyl ketone-derived linker (sensitive to irradiation at 305 nm) and a nitroveratryloxycarbonyl (NVOC) group (sensitive at 360 nm) was exploited to prepare Leu-Enkephalin in a 55% overall yield. This new strategy allows the preparation of peptides in essentially neutral medium, by avoiding the use of common deprotection reagents such as trifluoroacetic acid or piperidine.
- Kessler, Martin,Glatthar, Ralf,Giese, Bernd,Bochet, Christian G.
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p. 1179 - 1181
(2007/10/03)
-
- Synthesis of 10,11-dihydroleukotriene B4 metabolites via a nickel- catalyzed coupling reaction of cis-bromides and trans-alkenyl borates
-
Synthesis of 10,11-dihydro-, 10,11,14,15-tetrahydro-, and 10,11-dihydro- 12-oxoleukotriene B4 compounds (2, 4, 5) was accomplished stereoselectively by using the nickel-catalyzed coupling reaction illustrated in Scheme 1. The C(1)-C(7) fragments, TBS ether 10a for 2 and 4 and ethyoxyethyl (EE) ether 10b for 5, were prepared in enantiomerically pure forms (>99% ee) by a modified literature procedure (ref 11a). On the other hand, boronate esters 11a and 11b, which correspond to the C(8)-C(20) parts of 2 and 4, respectively, were synthesized from (R)-epichlorohydrin of 99% ee. Briefly, 18 was converted into acetylenes 24 and 32 through epoxide ring-opening with LiC≡CC5H11/BF3·OEt2 or C7H15MgBr/CuCN. Hydroboration of these acetylenes with (+)-(Ipc)2BH followed by reaction with MeCHO afforded the corresponding diethyl boronates, which upon ligand exchange with Me2C(CH2OH)2 furnished boronate esters 11a and 11b in 75% and 77% yields, respectively. In a similar manner, racemic boronate ester rac-11a, an intermediate for synthesis of 5, was prepared from racemic epichlorohydrin. For synthesis of 2, borate 25 was generated from 11a (1.5 equiv) and MeLi (1.6 equiv). Without isolation, 25 was submitted to reaction with 10a (1 equiv) in the presence of a Ni(0) species at room temperature overnight to afford 26, which upon treatment with TBAF furnished 2 in 64% yield from 10a. Similarly, 11b and 10a furnished 4 in good yield. To synthesize 5, rac-11a and EE ether 10b were joined by the coupling reaction to produce 39, which was transformed into 40 by desilylation with TBAF. After hydrolysis of 40, oxidation with PDC followed by deprotection of the EE group furnished 5 in 36% yield from 40. In addition, 2 was converted into amide 3 in 92% yield.
- Nakayama, Yuji,Kumar, G. Biju,Kobayashi, Yuichi
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p. 707 - 715
(2007/10/03)
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- Enzymatic Preparation of Alkanedicarboxylic Acid Monoesters
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Hydrolysis of alkanedicarboxylic acid dimethyl esters using esterase from Pseudomonas putida MR-2068 gave exclusively pure monoesters.Hydrolytic activities were dependent on the carbon chain length of the substrates.This esterase also catalyzed enantio- and regio-selective hydrolysis of α-methylalkanedicarboxylic acid dimethyl esters.
- Ozaki, Eiji,Uragaki, Toshitaka,Sakashita, Keiichi,Sakimae, Akihiro
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p. 539 - 540
(2007/10/03)
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- Les heteropolyacides comme catalyseurs bifonctionnells pour la coupure oxydante de cyclanones
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In the presence of dioxygen, heteropolyacids "H(3+n),aq" (HPA-n; n = 1-4), react with cyclanones to afford carboxylic acids.Treatment of 2-methylcyclohexanone gives 6-oxoheptanoic acid in high yields.Reaction of cyclohexanone with "HPA-n/AcOH-H2O/O2" systems affords adipic acid, glutaric acid, succinic acid and carbon dioxide.The byproducts arise predominantly by 6-oxohexanoic acid degradation.The reaction of hydrogen peroxide with molybdenum trioxide, vanadium(V) oxide and orthophosphoric acid has been studied and the formation of HPA-n has been obtained at room temperature in a short time. - Keywords: catalytic oxidation, cycloalkanones, heteropolyacids, dioxygen
- Atlamsani, A.,Ziyad, M.,Bregeault, J. M.
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p. 1344 - 1364
(2007/10/02)
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- Synthesis of 5,12-DiHETE Derivative by Palladium-Catalyzed Ternary Coupling between Vinylic Halide, a Vinylic Tin Compound, and Norbornadiene
-
A racemic 5,12-DiHETE-8,9-cyclopentadiene Diels-Alder adduct was prepared by palladium-catalyzed ternary coupling between vinylic halide, a vinylic tin compound, and norbornadiene in good yields.Both the halide and tin chain were synthesized in excellent yields by three and four steps, respectively.
- Oda, Hiroshi,Kobayashi, Tohru,Kosugi, Masanori,Migita, Toshihiko
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p. 695 - 702
(2007/10/02)
-
- Facile Synthesis of Stable Analogues of 2-Oxocyclobutanecarboxylates: 2-cyclobutanecarboxylates, Derivatives, and Reactions
-
An efficient two-step synthesis of 2-cyclobutenecarboxylate (4a) and some analogous derivatives from 2-chloro-2-cyclopropylideneacetates 2, 17, 22, and 25 and nonenolizable ketimines, especially diphenylmethyleneamine (DPMA-H), is described.A likely mechanism for the formation of 4a from the primary Michael adduct 3 of DPMA-H to 2 and its substuituted analogues is presented.The unique neighbouring group effect of the DPMA moiety to allow formation of an azaspiropentane intermediate and its regioselective rearrangement to cyclobutenaminederivatives is discussed and further exemplified by an extremely facile SET α-chlorination.Compound 4a and derivatives undergo a thermal ring-opening reaction to the corresponding butadienes with subsequent formation of 1,3-disubstituted 3,4-dihydroisoquinolines 39.Further transformations of 4a and some derivatives include transesterification, hydrolysis to methyl 2-oxocyclobutanecarboxylates, and addition of N-phenyltriazolinedione.
- Wessjohann, Ludger,Giller, Karsten,Zuck, Bernd,Skattebol, Lars,Meijere, Armin de
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p. 6442 - 6450
(2007/10/02)
-
- Enolic Radical Derived from Acetic Acid: A Useful Radical Alternative to Acetate Enolate in Michael-Type Reactions
-
The reaction of iodoacetic acid 1 with tributyltin chloride and sodium borohydride in the presence of different electrophilic olefins 2 (methyl, allyl or tert-butyl acrylates, N,N-dimethyl or N,N-di-iso-propyl acrylamides, acrylonitrile, methyl methacrylate, methacrylonitrile and 1,1-dichloroethylene) and AIBN as an initiator yields, after treatment with aqueous sodium fluoride, the corresponding products 3 through a radical Michael-type process.
- Foubelo, Francisco,Lloret, Francisco,Yus, Miguel
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p. 8465 - 8470
(2007/10/02)
-
- SELECTIVE MONOMETHYL ESTERIFICATION OF DICARBOXYLIC ACIDS BY USE OF MONOCARBOXYLATE CHEMISORPTION ON ALUMINA.
-
The application of alumina as a solid support affords a new procedure for selective reactions. Although it is difficult to obtain monoesters in the esterification of dicarboxylic acids by conventional methods, dicarboxylic acids adsorbed on alumina selectively form the monoesters. Terephthalic acid (1), isophthalic acid, cis- and trans-1,4-cyclohexanedicarboxylic acids, and aliphatic dicarboxylic acids give the corresponding monomethyl esters quantitatively with diazomethane. On the basis of these results, the authors suggest that dicarboxylic acids are adsorbed on alumina through one of their carboxyl groups, and the carboxyl group not adsorbed on the alumina is esterified selectively. Selective monomethyl esterification of phthalic acid is not successful on alumina, probably as a consequence of the close proximity of the two carboxyl groups and the forced orientation of the second group when one is adsorbed.
- Ogawa,Chihara,Taya
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p. 1365 - 1369
(2007/10/02)
-
- Enantiotopically Selective Oxidation of α,ω-Diols with the Enzyme Systems of Microorganisms
-
Gluconobacter were found to be capable of oxidizing prochiral diols such as 2-substituted propane-1,3-diols 1 and 3-substituted pentane-1,5-diols 4 with distinction of pro-R and pro-S sites of the molecules, in that (-)-(R)-α-substituted β-hydroxypropionic acids 2 and (+)-(3S)-3-substituted δ-valerolactones 5 were obtained, respectively.Oxidation of 3-methylpentane-1,3,5-triol 11 afforded unnatural (+)-(S)-mevalonolactone 12.The steric bulkiness of the substituents on the prochiral center and the distance from the hydroxy group greatly affected the rate and the enantioselectivity of the reaction.
- Ohta, Hiromichi,Tetsukawa, Hatsuki,Noto, Naoko
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p. 2400 - 2404
(2007/10/02)
-