- Enoate reductase-mediated preparation of methyl (S)-2-bromobutanoate, a useful key intermediate for the synthesis of chiral active pharmaceutical ingredients
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Enoate reductases belonging to the Old Yellow Enzyme (OYE) family were employed to develop a biocatalysed approach to methyl (S)-2-bromobutanoate, a key intermediate for the introduction of a particular stereogenic unit into the molecular skeleton of a certain class of chiral drugs. Methyl (Z)-2-bromocrotonate afforded, respectively, (S)-2-bromobutanoic acid (ee = 97%) and methyl (S)-2-bromobutanoate (ee = 97%) by baker's yeast fermentation and by OYE1-3 biotransformations. The bioreductions of other methyl 2-haloalkenoates were also considered. It was observed that the (Z)- and (E)-diastereoisomers of α-bromo unsaturated esters afforded the same enantiomer of the corresponding reduced product.
- Brenna, Elisabetta,Gatti, Francesco G.,Manfredi, Alessia,Monti, Daniela,Parmeggiani, Fabio
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p. 262 - 268
(2012/06/18)
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- Evaluation of snake venom phospholipase A2: Hydrolysis of non-natural esters
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Phospholipase A2 from the rattlesnake Crotalus durissus terrificus was employed for the first time to test its enantioseletivity on the hydrolysis of different non-natural esters. It was observed that the structure of this small enzyme is restrictive in the choice of its lipase action with non-natural substrates. Two forms of the enzyme were used; free and as its cross-linked enzyme aggregate (CLEA). With all substrates, the free enzyme showed activity similar to the CLEA preparation. The advantage of the CLEA phospholipase is the possibility to reuse it in several consecutive reactions without a decrease of activity and selectivity with good but higher yields and ee than with the free enzyme.
- Pirolla, Renan A. S.,Baldasso, Paulo A.,Marangoni, Se?rgio,Moran, Paulo J. S.,Rodrigues, Jose? Augusto R.
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p. 300 - 307
(2011/10/05)
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- Superparamagnetic nanoparticle-supported enzymatic resolution of racemic carboxylates
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Candida rugosa lipase immobilized on maghemite nanoparticles demonstrated high stereoselectivity in kinetic resolution of racemic carboxylates and improved long-term stability over its parent free enzyme, allowing the supported enzyme to be repeatedly used for a series of chiral resolution reactions. The Royal Society of Chemistry 2005.
- Gardimalla, Hari M. R.,Mandal, Deendayal,Stevens, Philip D.,Yen, Max,Gao, Yong
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p. 4432 - 4434
(2007/10/03)
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- Mesoionic 5-alkyl-1,3-dithiolium-4-thiolates: Synthesis and brine shrimp toxicity
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A series of twelve 1,3-dithiolium-4-thiolate mesoionic compounds were synthesized and characterized. The synthetical approach starting from α-bromoalkanoic acids to obtain the corresponding 2-N-morpholino-dithiocarbamoyl-carboxylic acids that by on-pot reaction with carbon disulfide and acetic anhydride in triethylamine formed not isolate intermediates, 1,3-dithiolium-4-olates. After, the 2-N-morpholino-5-alkyl-1,3-dithiolium-4-thiolates were obtained by retro 1,3-dipolar addition reactions. The alkyl moiety linked to C-5 of heterocyclic ring permitted the increase of the hydrophobic character and this effect was evaluated on Artemia salina lethality. The results indicated a bell-shaped relationship between the number of carbon of side chain in mesoionic derivatives and LD50 in brine shrimp toxicity assays.
- De Almeida, Paulo Afonso,Da Silva, Tania Maria Sarmento,Echevarria, Aurea
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p. 593 - 600
(2007/10/03)
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- Design and synthesis of potent thiol-based inhibitors of endothelin converting enzyme-1
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Through directed screening of compounds prepared as metalloprotease inhibitors a compound, CGS 30084, that had potent endothelin converting enzyme-1 (ECE-1) in vitro inhibitory activity (IC50=77nM) was identified. Herein we report the synthesis and optimization of ECE-1 inhibitory activity of additional analogues from this lead. Compound 3c, the thioacetate methyl ester derivative of compound 4c, was found to be a long acting inhibitor of ECE-1 activity in rats after oral administration. (C) 2000 Elsevier Science Ltd.
- Fink, Cynthia A.,Moskal, Michael,Firooznia, Fariborz,Hoyer, Denton,Symonsbergen, David,Wei, Dongchu,Qiao, Ying,Savage, Paula,Beil, Michael E.,Trapani, Angelo J.,Jeng, Arco Y.
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p. 2037 - 2039
(2007/10/03)
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- Enantioselective synthesis of α-bromo acid derivatives and bromohydrins from tartrate derived bromoacetals
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Bromination of the acetals 4 derived from aryl alkyl ketones, ArCOR, and (2R,3R)-tartaric acid results in bromoacetals 5 with 78-90% de. Hydrolysis of those compounds with Ar = 4-methoxyphenyl or 3-bromo-4-methoxyphenyl results, after recrystallisation, in α-bromoketones 8 with 66-98% ee which are shown to undergo the Baeyer-Villiger oxidation to α-bromoesters 9 with minimal racemisation, α-Bromoketone 8d is shown to undergo carbonyl reduction to threo-bromohydrin 15 with retention of stereochemistry.
- Boyes, Scott A.,Hewson, Alan T.
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p. 2759 - 2765
(2007/10/03)
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- A simple and efficient method of preparing α-bromo carboxylic acids
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A new and convenient method for α-bromination of aliphatic carboxylic acids is reported. Heating carboxylic acids for 16 hours at 85 °C in trifluoroacetic acid with 1.5 equivalents of N-bromosuccinimide and a catalytic amount of concentrated H2SO4 leads to good yields of the respective α-bromocarboxylic acids.
- Zhang, Lian Hao,Duan, Jianxin,Xu, Yuelian,Dolbier Jr., William R.
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p. 9621 - 9622
(2007/10/03)
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- Syntheses and biological activities of bombesin analogs modified in the C-terminal dipeptide part
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Bombesin receptor antagonists are possible therapeutic agents due to their ability to act as inhibitors of cellular proliferation. On the basis of our hypothesis on the mechanism of action of gastrin associating an activating enzyme system to the receptor and on the results reported in the litterature, we have synthesized bombesin analogues which have been modified in the C-terminal Leu13-Leu14 amide part. We have shown that modification in the C-terminal part of the bombesin strongly affected the biological activity in rat pancreatic acini. The most potent compound which is described here, H-D-Phe-Gln-Trp-Ala-Val-Gly-His-Leu-Ψ/(CH2)Leu-NH2, was able to recognize the bombesin receptor on rat pancreatic acini (Ki 4.3 nM) and antagonized the bombesin stimulated amylase secretion (Ki 7.7 nM).
- Llinares,Devin,Azay,Berge,Fehrentz,Martinez
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p. 767 - 780
(2007/10/03)
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- Asymmetric Synthesis of 2-Chloro- and 2-Bromo-alkanoic acids by Halogenation of α-D-Glucofuranose-Derived Silyl Ketene Acetals.
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Optically active (S)-2-bromo- and 2-chloro-alkanoic acids 6 and 7 have been obtained via the diastereoselective halogenation of chiral silyl ketene acetals 3a-f, and subsequent saponification of the resulting crude esters.Examples characterized by e.e. values up to 95percent are reported.The diastereoface selectivity is independent of the silyl ketene acetal E/Z configuration.
- Angibaud, P.,Chaumette, J. L.,Desmurs, J. R.,Duhamel, L.,Ple, G.,et al.
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p. 1919 - 1932
(2007/10/03)
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- HYDROXAMIC ACID COLLAGENASE INHIBITORS
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Compounds of general formula I: STR1 wherein: R 1 represents a hydrogen atom or a C 1-C 6 alkyl, C 1-C 6 alkenyl, phenyl, phenyl(C 1-C 6)alkyl, C 1-C 6 alkylthiomethyl, phenylthiomethyl, substituted phenylthiomethyl, phenyl(C. sub.1-C 6) alkylthiomethyl or heterocyclylthiomethyl group; or R 1 represents--SR x wherein R x represents a group STR2 R. sup.2 represents a hydrogen atom or a C 1-C 6 alkyl, C 1-C. sub.6 alkenyl, phenyl(C 1-C 6)alkyl, cycloalkyl(C 1-C 6) alkyl, or cycloalkenyl(C 1-C 6)alkyl;R 3 represents an amino acid residue with R or S stereochemistry or a C 1-C 6 alkyl, benzyl, (C 1-C 6)alkoxybenzyl or benzyloxy(C 1-C 6) alkyl group;R 4 represents a hydrogen atom or a methyl group;n is an integer from 1 to 6; and A represents the group--NH 2, a substituted acyclic amine or a heterocyclic base;or a salt and/or N-oxide and/or (where the compound is a thio-compound) a sulphoxide or sulphone thereof have collagenase inhibition activity and are useful in the management of disease involving tissue degradation and/or the promotion of wound healing. Diseases involving tissue degradation include arthropathy (particularly rheumatoid arthritis), inflammation, dermatological diseases, bone resorption diseases and tumour invasion.
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- Hydroxamic acid based collagenase inhibitors
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Compounds of general formula I: STR1 wherein: R1 represents a C1 -C6 alkyl, phenyl, thiophenyl, substituted phenyl, phenyl(C1 -C6)alkyl, heterocyclyl, (C1 -C6)alkylcarbonyl phenacyl or substituted phenacyl group; or, when n=O, R1 represents SRx, wherein Rx represents a group: STR2 R2 represents a hydrogen atom or a C1 -C6 alkyl, C1 -C6 alkenyl, phenyl (C1 -C6) alkyl, cycloalkyl(C1 -C6)alkyl or cycloalkenyl(C1 -C6)alkyl group; R3 represents an amino acid residue with R or S stereochemistry or a C1 -C6 alkyl, benzyl, (C1 -C6 alkoxy)benzyl or benzyloxy(C1 -C6 alkyl) group; R4 represents a hydrogen atom or a C1 -C6 alkyl group; R5 represents a hydrogen atom or a methyl group; n is an integer having the value 0, 1 or 2; and A represents a C1 -C6 hydrocarbon chain, optionaly substituted with one or more C1 -C6 alkyl, phenyl or substituted phenyl groups; and their salts and N-oxides are collagenase inhibitors are and useful in the management of disease involving tissue degradation and/or the promotion of wound healing. Diseases involving tissue degradation include arthropathy (particularly rheumatoid arthritis), inflammation, dermatological diseases, bone resorption diseases and tumour invasion.
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- New Reagents, XXXVII - (α-Lithioalkyl)diphenylarsane Oxides: Synthesis and Application for the Indirect Nucleophilic Haloalkylation
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Due to ready accessibility and high nucleophilicity (α-lithioalkyl)diphenylarsane oxides (2) are favorable reagents for the synthesis of many organoarsenic compounds.In organic synthesis they are recommendable as reagents for indirect nucleophilic haloalkylation reactions (Hal = Cl, Br, I).
- Kauffmann, Thomas,Joussen, Rolf,Woltermann, Annegret
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p. 2135 - 2142
(2007/10/02)
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