- Practical acetalization and transacetalization of carbonyl compounds catalyzed by recyclable PVP-I
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A novel PVP-I catalyzed acetalizations/transacetalizations of carbonyl compounds has been developed processing with a mild and easy handling fashion. Different types of Acyclic and cyclic acetals were prepared from carbonyl compounds or their acetals successfully. Further applications of newly developed catalytic combination were testified. This protocol featured with simplicity of operation, mild reaction condition, short reaction time, recyclable of catalyst and broad substrates scope with excellent yields.
- Cao, Fu-Rong,Lu, Guangying,Ren, Jiangmeng,Wang, Di,Zeng, Bu-Bing
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- Activated Self-Resolution and Error-Correction in Catalytic Reaction Networks**
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Understanding the emergence of function in complex reaction networks is a primary goal of systems chemistry and origin-of-life studies. Especially challenging is to create systems that simultaneously exhibit several emergent functions that can be independently tuned. In this work, a multifunctional complex reaction network of nucleophilic small molecule catalysts for the Morita-Baylis-Hillman (MBH) reaction is demonstrated. The dynamic system exhibited triggered self-resolution, preferentially amplifying a specific catalyst/product set out of a many potential alternatives. By utilizing selective reversibility of the products of the reaction set, systemic thermodynamically driven error-correction could also be introduced. To achieve this, a dynamic covalent MBH reaction based on adducts with internal H-transfer capabilities was developed. By careful tuning of the substituents, rate accelerations of retro-MBH reactions of up to four orders of magnitude could be obtained. This study thus demonstrates how efficient self-sorting of catalytic systems can be achieved through an interplay of several complex emergent functionalities.
- Schaufelberger, Fredrik,Ramstr?m, Olof
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supporting information
p. 10335 - 10340
(2021/05/07)
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- Inhibition by Water during Heterogeneous Br?nsted Acid Catalysis by Three-Dimensional Crystalline Organic Salts
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A new self-assembled and self-healing class of metal free, recyclable, heterogeneous Br?nsted acid catalysts has been developed by the protonation of aniline derivatives (tetrakis(4-aminophenyl)methane, leuco-crystal violet, benzidine, and p-phenylenediamine) with aromatic sulfonic acids (tetrakis(phenyl-4-sulfonic acid)methane, and 2,6-naphthalenedisulfonic acid). As a result, five three-dimensional crystalline organic salts (F-1a, F-1b, F-1c, F-2, and F-3) were obtained, linked by hydrogen bonds and additionally stabilized by the opposite charges of the components. Frameworks F-2 and F-3 were prepared for the first time and characterized by elemental analysis, X-ray structural analysis (for F-2), thermogravimetry, SEM, and FTIR spectroscopy. The catalytic activities of crystalline organic salts F-1-3 have been explored in industrially important epoxide ring-opening and acetal formation reactions. The presence of encapsulated water inside frameworks F-1a and F-2 had an inhibitory effect on the performance of the catalysts. X-ray diffraction analysis of hydrated and dehydrated samples of F-1a and F-2 indicated that water of crystallization served as a cross-linking agent, diminishing the substrate induced "breathing"affinities of the frameworks.
- Belokon, Yuri N.,Gak, Alexander,Khakina, Ekaterina,Khrustalev, Victor N.,Korlyukov, Alexander A.,Kuznetsova, Svetlana,Li, Han,Lobanov, Nikolai,Nelyubina, Yulia,North, Michael,Peregudov, Alexander S.,Riazanov, Vladimir,Zhereb, Vladimir
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p. 6364 - 6372
(2021/10/20)
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- Preparation method of ambroxol hydrochloride
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The invention relates to a preparation method of ambroxol hydrochloride, and the method comprises the following steps: carrying out aldehyde group protection on o-nitrobenzaldehyde, and reducing hydrazine hydrate in the presence of a catalyst NiCoB/TiO2 to obtain a compound 3; carrying out bromination reaction on the compound 3 under the action of molecular bromine and hydrogen peroxide, and carrying out deprotection to generate a compound 2; and carrying out aldehyde reductive amination reaction with trans-4-aminocyclohexanol under the action of catalysts NaBH (OAc) 3 and LiClO4, and salifying to obtain the ambroxol hydrochloride. The method has the advantages of mild conditions, simple steps, environmental friendliness, easily stored raw materials and high yield, and is suitable for industrial production.
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Paragraph 0034-0047; 0068-0071
(2020/05/14)
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- Chiroptical Asymmetric Reaction Screening via Multicomponent Self-Assembly
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Self-assembly of a stereodynamic phosphine ligand, Pd(II), and a chiral amine, amino alcohol, or amino acid generates characteristic UV and CD signals that can be used for quantitative stereochemical analysis of the bound substrate. A robust mix-and-measure chiroptical sensing protocol has been developed and used to determine the absolute configuration, ee, and yield of an amine produced by Ir-catalyzed asymmetric hydrogenation of an iminium salt. The analysis requires only 1 mg of the crude reaction mixture and minimizes cost, labor, time, and waste.
- De Los Santos, Zeus A.,Wolf, Christian
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supporting information
p. 13517 - 13520
(2016/10/31)
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- Synthesis and characterization of a tetracationic acidic organic salt and its application in the synthesis of bis(indolyl)methanes and protection of carbonyl compounds
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A new tetracationic acidic organic salt (TCAOS) based on DABCO was prepared, characterized and applied as an eco-friendly, powerful and reusable catalyst for the synthesis of bis(indolyl)methanes from indoles and carbonyl compounds in water with high turnover frequency (TOF). Also, this catalyst was successfully applied for acetalization of carbonyl compounds with diols under solvent-free conditions.
- Halimehjani, Azim Ziyaei,Hooshmand, Seyyed Emad,Shamiri, Elham Vali
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p. 21772 - 21777
(2015/03/18)
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- Acetalization of aldehydes and ketones over H4[SiW 12O40] and H4[SiW12O 40]/SiO2
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H4[SiW12O40] (H-SiW12) is demonstrated to be able to efficiently catalyze the acetalization of aldehydes and ketones with ethylene glycol and 1,3-propanediol. Nevertheless, the possible leaching and the recycling of H-SiW12 are two major disadvantages that largely restrict its further application in industry. Moreover, H 4[SiW12O40] tends to deactivate strong proton sites due to the small surface area of 10 m2 g-1. Due to interactions with surface silanol groups, the proton sites of polyoxometalates (POMs) on SiO2 are less susceptible to deactivation. As such, immobilization of H4[SiW12O40] onto SiO 2 leads to the heterogeneous catalyst H4[SiW 12O40]/SiO2 (H-SiW12/SiO 2), which can catalyze the acetalization of aldehydes and ketones with ethylene glycol and 1,3-propanediol selectively and efficiently without the need of a drying agent. The acetalization process can proceed smoothly at a relatively low temperature under solvent-free conditions. The catalyst of H 4[SiW12O40]/SiO2 can be recycled at least ten times without an obvious decrease in its catalytic activity. As far as we know, the TONs of the H-SiW12/SiO2-catalyzed acetalization of cyclohexanone with ethylene glycol, and benzaldehyde with 1,3-propanediol are the highest reported so far.
- Zhao, Shen,Jia, Yueqing,Song, Yu-Fei
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p. 2618 - 2625
(2014/07/22)
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- A facile and efficient protocol for esterification and acetalization in a PEG1000-D(A)IL/toluene thermoregulated catalyst-media combined systems
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A novel efficient and recyclable temperature-dependent biphasic catalyst and reaction media combined system comprised of PEG-1000 linked dicationic acidic ionic liquid and toluene was developed and applied in esterification of aromatic acids and acetalization of aromatic aldehydes with good to excellent yields. This system is characteristic of temperature-dependent reversible biphasic property, simple and facile recyclability, high catalytic activity and extensive substrate and reaction adaptability.
- Wang, Yinglei,Zhi, Huizhen,Luo, Jun
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- Mesoporous sulfated zirconia mediated acetalization reactions
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A novel, convenient, one step synthetic procedure for the synthesis of mesoporous sulfated zirconia (m-SZ) using zirconium carbonate complex and its use as solid acid catalyst for the acetalization of different carbonyl compound is reported. The high specific BET surface area (234 m2 g -1) of m-SZ is achieved after the removal of the surfactant (cetyltrymethylammonium bromide, CTAB) through calcination at 550 °C for 6 h. Microscopic analysis indicated the presence of spherical particles with worm like pores. DRIFT (diffuse reflectance FTIR) of pyridine adsorbed m-SZ and NH3-TPD (temperature programmed desorption) analysis suggested the presence of appreciable amount of Bro?nsted acid sites. The synthesized m-SZ showed high catalytic activity towards protection of carbonyl compounds through acetal/ketal formation. For the open ketal (from cyclohexanone and methanol) 97% conversion with 100% selectivity was obtained in 1 h at room temperature under solvent free condition. The catalyst can be easily recycled after separation from the reaction system without considerable loss in catalytic activity.
- Sinhamahapatra, Apurba,Sutradhar, Narottom,Ghosh, Malay,Bajaj, Hari C.,Panda, Asit B.
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experimental part
p. 87 - 93
(2012/04/10)
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- Acetalization of carbonyl compounds catalyzed by bismuth triflate under solvent-free conditions
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Carbonyl compounds were converted to the corresponding 1,3-dioxolanes and 1,3-dioxanes with ethylene glycol and 1,3-propandiol in the presence of bismuth triflate under solvent-free conditions. In addition, high chemoselective protection of aldehydes in the presence of ketones has been achieved.
- Aliyan, Hamid,Fazaeli, Razieh,Massah, Ahmad Reza,Momeni, Ahmad Reza,Naghash, Hamid Javaherian,Moeinifard, Behzad
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experimental part
p. 873 - 876
(2012/04/05)
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- [Hmim]3PW12O40: A high-efficient and green catalyst for the acetalization of carbonyl compounds
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[Hmim]3PW12O40 was developed and used in the acetalization of carbonyl compounds in excellent yields. The ionic liquid-heteropoly acid hybrid compound and reaction medium formed temperature-dependent phase-separation system with the ease of product as well as catalyst separation. The catalyst was recycled more than 10 times without any apparent loss of catalytic activity.
- Dai, Yan,Li, Bin Dong,Quan, Heng Dao,Lü, Chun Xu
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experimental part
p. 678 - 681
(2011/10/31)
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- Relaying stereochemistry through aromatic ureas: 1,9 and 1,15 remote stereocontrol
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The well-defined conformation of an N,N′-diarylurea allows a chiral sulfinyl substituent to influence diastereoselectivity in the formation of new stereogenic centres up to 14 bond lengths away. The Royal Society of Chemistry.
- Clayden, Jonathan,Pickworth, Mark,Jones, Lyn H.
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supporting information; experimental part
p. 547 - 549
(2009/06/17)
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- Highly efficient and chemoselective acetalization of carbonyl compounds catalyzed by new and reusab e zirconyl triflate, zr0(0tf)2
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Various types of aromatic aldehydes were efficiently converted to their corresponding 1,3-dioxanes and 1,3-dioxolane with 1,3-propanediol and ethylene glycol, respectively, in the presence of catalytic amount of ZrO(OTf) 2 in acetonitrile at room temperature. The catalyst can be reused several times without loss of its catalytic activity. Very short reaction times, selective acetalization of aromatic aldehydes in the presence of aliphatic aldehydes and ketones, very mild reaction conditions, reusability of the catalyst, and easy workup are noteworthy advantages of this method.
- Moghadam, Majid,Mohammadpoor-Baltork, Iraj,Tangestaninejad, Shahram,Mirkhani, Valiollah,Yazdani, Parvin,Ghorjipoor, Saeedeh
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experimental part
p. 131 - 135
(2009/09/30)
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- Design and synthesis of novel N-benzylidenesulfonohydrazide inhibitors of murC and murD as potential antibacterial agents
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A series of novel N-benzylidenesulfonohydrazide compounds were designed and synthesized as inhibitors of UDP-N-acetylmuramic acid:L-alanine ligase (MurC) and UDP-N-acetylmuramoyl-L-alanine:D-glutamate ligase (MurD) from E. coli, involved in the biosynthes
- Frlan, Rok,Kovac, Andreja,Blanot, Didier,Gobec, Stanislav,Pecar, Slavko,Obreza, Ales
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- Formation of dioxolane on the surface of silica-sulphuric acid in dry media - Chemoselective protection of aryl aldehydes
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Chemoselective protection of aryl aldehydes can be accomplished through the formation of dioxolane on the surface of silica-sulphuric acid under solvent-free conditions where aliphatic aldehydes, dialkyl ketones, aryl alkyl ketones, and diaryl ketones rem
- Saha, Manabendra,Roy, Sanchita,Chaudhuri, Subrata Kumar,Bhar, Sanjay
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p. 1989 - 1993
(2008/02/04)
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- Intermolecular reactions of chlorohydrine anions: Acetalization of carbonyl compounds under basic conditions
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Nonenolizable aldehydes and ketones react with 2-chloroethanol and 3-chloropropanol under basic conditions (t-BuOK, DMF/THF) with formation of 2-substituted 1,3-dioxolanes and 1,3-dioxanes, respectively. Conversion of the two-step addition-alkylation process depends on the electrophilicity of the carbonyl group that governs the equilibrium of addition of chloroalkoxides. This method of protection of carbonyl groups in the form of cyclic acetals under kinetically controlled conditions is complementary to the acid-catalyzed reaction with diols.
- Barbasiewicz, Michal,Makosza, Mieczyslaw
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p. 3745 - 3748
(2007/10/03)
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- A remarkable iodine-catalyzed protection of carbonyl compounds
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We report here a remarkably simple molecular iodine-catalyzed protection method for various carbonyl compounds as ketals in a general reaction. The iodine-catalyzed reaction of mandelic acid and lactic acid with several aldehydes has furnished a highly diastereoselective synthesis of cis and trans dioxolanones.
- Banik, Bimal K.,Chapa, Marin,Marquez, Jocabed,Cardona, Magda
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p. 2341 - 2343
(2007/10/03)
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- An efficient procedure for protection of carbonyls in Br?nsted acidic ionic liquid [Hmim]BF4
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Protection of carbonyls as acetals or ketals using Br?nsted acidic ionic liquid [Hmim]BF4 as catalyst as well as solvent was investigated. Satisfactory results were obtained for the protection of carbonyls as cycloacetals or ketals with diols. The product can be separated conveniently from the reaction system, and the ionic liquid can be reused after removal of water.
- Wu, Hai-Hong,Yang, Fan,Cui, Peng,Tang, Jie,He, Ming-Yuan
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p. 4963 - 4965
(2007/10/03)
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- A new approach to the synthesis of 2-nitrobenzaldehyde. Reactivity and molecular structure studies
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New approaches to the synthesis of 2-nitrobenzaldehyde by formation and selective isomer separation of 2-nitrophenyl-1,3-dioxolane and further hydrolysis are reported. In this route, the same acidic heterogeneous catalyst is used for 1,3-dioxolane formation and hydrolysis; it can be recycled several times without loss of efficiency. The ortho/meta isomers of 2-nitrophenyl-1,3-dioxolane can be separated by a combination of stereoselective crystallization and fractionated distillation. This new route reduces safety and environmental hazards in the synthesis of 2-nitro- and 3-nitro-benzaldehydes. The molecular structures of the nitro derivatives were confirmed by 1H and 13C NMR spectroscopy. The results are in accordance with a non-coplanar conformer of the 2-nitro derivatives (2-nitrobenzaldehyde and 2-(2′-nitrophenyl)-1,3-dioxolane), where the nitro group is twisted with respect to the phenyl ring. In contrary, both the carbonyl and the nitro group are coplanar with the phenyl ring in 3-nitrobenzaldehyde. This result is consistent with the reactivity of the compounds.
- Sainz-Diaz
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- Eco-friendly Pt-Mo/ZrO2 solid acid catalyst for selective protection of carbonyl compounds
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An easy method for protection of carbonyl compounds has been carried out in excellent yields under catalysis of Pt-Mo/ZrO2 in toluene at 383 K.
- Reddy,Reddy,Giridhar
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p. 1819 - 1823
(2007/10/03)
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- Silica gel-supported metallic sulfates catalyzed chemoselective acetalization of aldehydes under microwave irradiation
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Silica gel - supported metallic sulfates are found to be efficient catalysts for the protection of both aromatic and aliphatic aldehydes as 1,3- dioxolanes under microwaves in solvent-free conditions. Due to the neutral reaction conditions, this method is compatible with acid sensitive substrates.
- Yadav,Reddy, B. V. Subba,Srinivas,Ramalingam
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p. 701 - 703
(2007/10/03)
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- Radiosynthesis of [18F]Lu29-024: a potential PET ligand for brain imaging of the serotonergic 5-HT2 receptor.
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In a previous work, Lu29-024 (2,5-dimethyl-3-(4-fluorophenyl)-1-(1-methyl-4-piperidinyl)-1H-indole), a selective 5-HT2A receptor antagonist with nanomolar affinity and high selectivity, was labeled with carbon-11 to evaluate its behavior as a potential PET ligand for the serotonergic 5-HT2A receptor in the central nervous system. Administration of this tracer to rats was followed by a good brain uptake, no brain labeled metabolites but no specific, regio-selective, binding at 20 and 40 min post injection. Despite this, the data noted at 20 and 40 min suggest that this tracer, if associated with a radioactive emitter with a longer half-life than that of carbon-11, could be useful for the quantification of 5HT2A receptors. For these reasons, we chose to label this compound, bearing a fluorine atom, with [18F]fluoride, in order to perform rat studies over a more prolonged time-scale. The precursor for the radiosynthesis of [18F]Lu29-024 was obtained in an overall yield of 20% by a multi-step synthesis including an acetonylation reaction followed by a Fisher indole reaction. The radiotracer was prepared by an aromatic substitution with activated [18F]fluoride followed by a decarbonylation reaction that employed Wilkinson's catalyst. The radiosynthesis of [18F]Lu29-024 required approximatively 110 min with an overall radiochemical yield of 20-35% and specific activities of 37GBq/micromol. Fluorine-labeled Lu29-024 may thus be envisaged as a potentially useful PET tracer that can be applied to a wide range of neurological and psychiatric diseases.
- Sobrio,Amokhtari,Gourand,Dhilly,Dauphin,Barre
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p. 2511 - 2518
(2007/10/03)
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- Microwave-assisted acetalization of carbonyl compounds catalyzed by reusable Envirocat supported reagents
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Envirocat supported reagents (EPZG, EPZ10, and EPIC) are found to efficiently catalyze the acetalization of carbonyl compounds with 1,2-ethanediol under microwave irradiation under solvent-free conditions. The reagents can be used in repeated experiments to perform the reaction with the same activity.
- Beregszaszi, Timea,Molnar, Arpad
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p. 3705 - 3709
(2007/10/03)
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- Novel Ring Cleavage Based on Intermolecular Aldol Condensation
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Ring cleavage and reconstruction via intramolecular aldol condensation followed by Grob fragmentation under acetalization conditions (BF3/ethylene glycol) was developed into a novel ring cleavage based on intermolecular aldol condensation.On the basis of
- Nagumo, Shinji,Matsukuma, Aki,Suemune, Hiroshi,Sakai, Kiyoshi
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p. 10501 - 10510
(2007/10/02)
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- Inhibitors of blood platelet cAMP phosphodiesterase. 2. Structure-activity relationships associated with 1,3-dihydro-2H-imidazo[4,5-b]quinolin-2-ones substituted with functionalized side chains
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A series of 1,3-dihydro-2H-imidazo[4,5-b]quinolin-2-one derivatives, substituted at the 7-position with functionalized side chains, was synthesized and evaluated as inhibitors of human blood platelet cAMP phosphodiesterase (PDE) as well as ADP- and collagen-induced platelet aggregation, in vitro. Structural modifications focused on variation of the side-chain terminus, side-chain length, and side-chain connecting atom. Functionality incorporated at the side-chain terminus included carboxylic acid, ester and amide, alcohol, acetate, nitrile, tetrazole, and phenyl sulfone moieties. cAMP PDE inhibitory potency varied and was dependent upon the side-chain terminus and its relationship with the heterocyclic nucleus. Methylation at N-1 or N-3 of the heterocycle diminished cAMP PDE inhibitory potency. Several representatives of this structural class demonstrated potent inhibition of ADP- and collagen-induced blood platelet aggregation and were half-maximally effective at low nanomolar concentrations. Amides 13d, 13f, 13h, 13k, 13m, and 13w are substantially more potent than relatively simply substituted compounds. However, platelet inhibitory properties did not always correlate with cAMP PDE inhibition across the series, probably due to variations in membrane permeability. Several compounds inhibited platelet aggregation measured ex vivo following oral administration to rats. Ester 11b, acid 12b, amide 13d, and sulfone 29c protected against thrombus formation in two different animal models following oral dosing and were found to be superior to anagrelide (2) and BMY 20844 (5). However, ester 11b and acid 12b demonstrated a unique pharmacological profile since they did not significantly affect hemodynamic parameters in dogs at doses 100-fold higher than that required for complete prevention of experimentally induced vessel occlusion in a dog model of thrombosis.
- Meanwell,Pearce,Roth,Smith,Wedding,Wright,Buchanan,Baryla,Gamberdella,Gillespie,Hayes,Seiler,Stanton,Zavoico,Fleming
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p. 2672 - 2687
(2007/10/02)
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