- Aspidosperma Alkaloids via Cyclization of Secodine Intermediate: Synthesis of (+/-)-3-Oxovincadifformine Ethyl Ester
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(+/-)-3-oxovincadifformine ethyl ester 14 has been synthesized through an intramolecular cycloaddition of the 3-oxosecodine 13 first prepared in turn from the enamide 10 by dehydrogenation with benzeneseleninic anhydride.An insight into the conversion of 10 into 13 was gained, resulting in the suggestion of a plausible mechanistic pathway.
- Danieli, Bruno,Lesma, Giordano,Palmisano, Giovanni,Passarella, Daniele,Silvani, Alessandra
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- Preparation of mono-substituted malonic acid half oxyesters (SMAHOs)
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The use of mono-substituted malonic acid half oxyesters (SMAHOs) has been hampered by the sporadic references describing their preparation. An evaluation of different approaches has been achieved, allowing to define the best strategies to introduce diversity on both the malonic position and the ester function. A classical alkylation step of a malonate by an alkyl halide followed by a monosaponification gave access to reagents bearing different substituents at the malonic position, including functionalized derivatives. On the other hand, the development of a monoesterification step of a substituted malonic acid derivative proved to be the best entry for diversity at the ester function, rather than the use of an intermediate Meldrum acid. Both these transformations are characterized by their simplicity and efficiency, allowing a straightforward access to SMAHOs from cheap starting materials.
- Condon, Sylvie,Le Gall, Erwan,Pichon, Christophe,Presset, Marc,Xavier, Tania
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supporting information
p. 2085 - 2094
(2021/09/02)
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- Hydrogen-Bonding Assisted Catalytic Kinetic Resolution of Acyclic β-Hydroxy Amides
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Enantioenriched acyclic α-substituted β-hydroxy amides are valuable compounds in chemical, material and medicinal sciences, but their enantioselective synthesis remains challenging. A catalytic kinetic resolution (KR) of such amides with selectivity factor(s) up to >200 is developed via enantioselective acylation of primary alcohol with N-heterocyclic carbene. An enhanced selectivity for the catalytic KR process is realized using cyclic tertiary amine as base additive. Diastereomeric transition state models for the process are proposed to rationalize the origin of enantioselectivity.
- Porey, Arka,Mondal, Bhaskar Deb,Guin, Joyram
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supporting information
p. 8786 - 8791
(2021/03/17)
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- 4-Hydroxy-3-methyl-2(1h)-quinolone, originally discovered from a brassicaceae plant, produced by a soil bacterium of the genus burkholderia sp.: Determination of a preferred tautomer and antioxidant activity
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4-Hydroxy-3-methyl-2(1H)-quinolone (1), a molecule known for a long time and recently discovered from a Brassicaceae plant Isatis tinctoria without providing sufficient evidence to support the structure, was isolated from a fermentation extract of Burkholderia sp. 3Y-MMP isolated from a soil by a Zn2+ enrichment culture. Detailed spectroscopic analyses by MS and NMR, combined with 13C chemical shift comparison with literature values of the related compounds and a synthetic preparation of 1, allowed its first full NMR characterization and identification of 2-quinolone but not 2-quinolinol (2) as the preferred tautomer for this heterocyclic system. While the metal-chelating activity was negligible, compound 1 at 10 μM, a concentration lower than that in liquid production cultures, quenched hydroxy radical-induced chemiluminescence emitted by luminol by 86percent. Because some Burkholderia species are pathogenic to plants and animals, the above result suggests that 1 is a potential antioxidant to counteract reactive oxygen species-based immune response in the host organisms.
- Igarashi, Yasuhiro,Kurokawa, Yoichi,Li, Dandan,Oku, Naoya,Shinozaki, Yukiko
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supporting information
p. 1489 - 1494
(2020/07/08)
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- Enantioselective α-Amination of Acyclic 1,3-Dicarbonyls Catalyzed by N-Heterocyclic Carbene
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Herein, we describe a method for the catalytic enantioselective α-amination of α-substituted acyclic 1,3-ketoamides and 1,3-amidoesters that affords the products possessing N-substituted quaternary stereocenters with a chiral N-heterocyclic carbene (NHC). The reaction is based on the utilization of an intrinsic Br?nsted base characteristic of NHC that enables the catalytic formation of a chiral ion pair comprising the enolate and the azolium ion. A series of challenging open-chain α-substituted 1,3-dicarbonyls are aminated via this method with ee's of ≤99%.
- Santra, Surojit,Maji, Ujjwal,Guin, Joyram
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supporting information
p. 468 - 473
(2020/02/04)
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- Synthetic access to 3,4-disubstituted pyroglutamates from tetramate derivatives from serine, allo-threonine and cysteine
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A route allowing the conversion of substituted tetramates to 3,4-disubstituted pyroglutamates, making use of Suzuki coupling on an enol mesylate, followed by reduction, is both general and fully stereoselective.
- Bagum, Halima,Christensen, Kirsten E.,Genov, Miroslav,Pretsch, Alexander,Pretsch, Dagmar,Moloney, Mark G.
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- Synthesis of α,β-Disubstituted Acrylates via Galat Reaction
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Galat reactions between aldehydes and substituted malonic acids half oxyester were found to be efficiently catalyzed by morpholine in refluxing toluene. This transformation allows the stereoselective synthesis of diverse α,β-disubstituted acrylates in moderate to good yields. This method constitutes an attractive alternative to existing methods in terms of scope and eco-compatibility.
- Xavier, Tania,Condon, Sylvie,Pichon, Christophe,Le Gall, Erwan,Presset, Marc
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supporting information
p. 6135 - 6139
(2019/08/28)
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- Palladium-Catalyzed [3 + 2]-C-C/N-C Bond-Forming Annulation
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The synthesis of bi- and tricyclic structures incorporating pyrrolidone rings is disclosed, starting from resonance-stabilized acetamides and cyclic α,β-unsaturated-γ-oxycarbonyl derivatives. This process involves an intermolecular Tsuji-Trost allylation/intramolecular nitrogen 1,4-addition sequence. Crucial for the success of this bis-nucleophile/bis-electrophile [3 + 2] annulation is its well-defined step chronology in combination with the total chemoselectivity of the former step. When the newly formed annulation product carries a properly located o-haloaryl moiety at the nitrogen substituent, a further intramolecular keto α-arylation can join the cascade, thereby forming two new cycles and three new bonds in the same synthetic operation.
- Liu, Yang,Mao, Zhongyi,Pradal, Alexandre,Huang, Pei-Qiang,Oble, Julie,Poli, Giovanni
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supporting information
p. 4057 - 4061
(2018/07/15)
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- Controlling Plasma Stability of Hydroxamic Acids: A MedChem Toolbox
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Hydroxamic acids are outstanding zinc chelating groups that can be used to design potent and selective metalloenzyme inhibitors in various therapeutic areas. Some hydroxamic acids display a high plasma clearance resulting in poor in vivo activity, though they may be very potent compounds in vitro. We designed a 57-member library of hydroxamic acids to explore the structure-plasma stability relationships in these series and to identify which enzyme(s) and which pharmacophores are critical for plasma stability. Arylesterases and carboxylesterases were identified as the main metabolic enzymes for hydroxamic acids. Finally, we suggest structural features to be introduced or removed to improve stability. This work thus provides the first medicinal chemistry toolbox (experimental procedures and structural guidance) to assess and control the plasma stability of hydroxamic acids and realize their full potential as in vivo pharmacological probes and therapeutic agents. This study is particularly relevant to preclinical development as it allows obtaining compounds equally stable in human and rodent models.
- Hermant, Paul,Bosc, Damien,Piveteau, Catherine,Gealageas, Ronan,Lam, Baovy,Ronco, Cyril,Roignant, Matthieu,Tolojanahary, Hasina,Jean, Ludovic,Renard, Pierre-Yves,Lemdani, Mohamed,Bourotte, Marilyne,Herledan, Adrien,Bedart, Corentin,Biela, Alexandre,Leroux, Florence,Deprez, Benoit,Deprez-Poulain, Rebecca
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p. 9067 - 9089
(2017/11/14)
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- [7,6]-FUSED BICYCLIC ANTIDIABETIC COMPOUNDS
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Novel compounds of the structural formula (I), and the pharmaceutically acceptable salts thereof, are agonists of G-protein coupled receptor 40 (GPR40) and may be useful in the treatment, prevention and suppression of diseases mediated by the G-protein-coupled receptor 40. The compounds of the present invention may be useful in the treatment of Type 2 diabetes mellitus, and of conditions that are often associated with this disease, including obesity and lipid disorders, such as mixed or diabetic dyslipidemia, hyperlipidemia, hypercholesterolemia, and hypertriglyceridemia.
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Page/Page column 68
(2016/04/20)
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- An improved solvent-free system for the microwave-assisted decarboxylation of malonate derivatives based on the use of imidazole
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A comparative study of the thermal and microwave-assisted decarboxylation of a series of mono- and disubstituted monohydrolyzed malonate derivatives has been carried out. It has been found out that in both circumstances the use of imidazole has a profound effect on the success of the reaction. In general terms the assistance of microwave irradiation accelerates the decarboxylation process significantly and, at the same time, permits the use of minored temperatures with respect to the thermal via. It has been also found that both the thermal and the microwave-assisted transformation can be developed under solvent-free conditions.
- Tellitu, Imanol,Beitia, Itziar,Díaz, Marta,Alonso, Argi?e,Moreno, Isabel,Domínguez, Esther
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p. 8251 - 8255
(2015/10/05)
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- The synthesis of α-azidoesters and geminal triazides
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Three simple methods for the synthesis of geminal triazides are described: Starting from 1) 3-oxocarboxylic acids, 2) iodomethyl ketones, or 3) terminal olefins, a range of triazidomethyl ketones can be constructed under mild oxidative reaction conditions by the use of IBX-SO3K, a sulfonylated derivative of 2-iodoxybenzoic acid (IBX), and NaN3 as an azide source. This is the first report of representatives of this novel class of triazide compounds: Despite their high nitrogen content, the geminal triazides are easy to handle, even when preparative-scale syntheses are performed. (Caution: These procedures still require protective measures!) The triazides are now broadly available for further studies regarding their properties and reactivity. Furthermore, we show how the method can be used to provide α-azidoesters, which are potential building blocks for amino acids. Either/or: Geminal triazides are rapidly constructed with broad scope by the use of oxocarboxylic acids, iodomethyl ketones, or terminal olefins as starting substrates in oxidative azidations with a mild derivative of 2-iodoxybenzoic acid and sodium azide. Along with this little-studied class of organic azides, α-azidoesters were also synthesized.
- Klahn, Philipp,Erhardt, Hellmuth,Kotthaus, Andreas,Kirsch, Stefan F.
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supporting information
p. 7913 - 7917
(2014/08/05)
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- Synthetic studies of the spirocyclic cyclohexene part of versipelostatin, a novel GRP78/Bip molecular chaperone downregulator
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The spirocyclic part consisting of an -acylated tetronic acid and a multisubstituted cyclohexene embedded in versipelostatin, a novel GRP78/Bip molecular chaperone downregulator, has been synthesized in enantiomerically pure form. The asymmetric synthesis of the targeted spiro4.5-1-oxa-7-decen-2,4-dione derivative was characterized by (1) stereoselective allylation at the -carbon of methylmalonate diester, in which one carboxylic acid was esterified with a D-glucose-derived chiral template, (2) construction of the tetrasubstituted cyclohexenone substructure by high-yielding ring-closing metathesis and (3) stereoselective construction of the spirocyclic tetronic acid part starting from the cyclohexenone obtained as the ring-closing metathesis product.
- Sasaki, Shu,Samejima, Suguru,Uruga, Tomoki,Anzai, Kai,Nishi, Natsumi,Kawakita, Eriko,Takao, Ken-Ichi,Tadano, Kin-Ichi
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p. 147 - 154
(2013/08/25)
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- Overturning established chemoselectivities: Selective reduction of arenes over malonates and cyanoacetates by photoactivated organic electron donors
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The prevalence of metal-based reducing reagents, including metals, metal complexes, and metal salts, has produced an empirical order of reactivity that governs our approach to chemical synthesis. However, this reactivity may be influenced by stabilization of transition states, intermediates, and products through substrate-metal bonding. This article reports that in the absence of such stabilizing interactions, established chemoselectivities can be overthrown. Thus, photoactivation of the recently developed neutral organic superelectron donor 5 selectively reduces alkyl-substituted benzene rings in the presence of activated esters and nitriles, in direct contrast to metal-based reductions, opening a new perspective on reactivity. The altered outcomes arising from the organic electron donors are attributed to selective interactions between the neutral organic donors and the arene rings of the substrates.
- Doni, Eswararao,Mondal, Bhaskar,O'Sullivan, Steven,Tuttle, Tell,Murphy, John A.
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p. 10934 - 10937
(2013/08/23)
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- Neutral nazarov-type cyclization catalyzed by palladium(0)
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Joining the circle: The first Pd0 catalyzed Nazarov-type cyclization of diketoesters (see scheme) proceeds in 70 % to 95 % yield under strictly neutral pH conditions. Aryl substitution of the diketoesters is not required, so the reaction shows great versatility and can also proceed with aliphatic substrates. Copyright
- Shimada, Naoyuki,Stewart, Craig,Bow, William F.,Jolit, Anais,Wong, Kahoano,Zhou, Zhe,Tius, Marcus A.
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supporting information; scheme or table
p. 5727 - 5729
(2012/08/07)
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- Hydroxamates: Relationships between structure and plasma stability
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Hydroxamates are valuable tools for chemical biology as well as interesting leads for medicinal chemistry. Although many hydroxamates display nanomolar activities against metalloproteases, only three hydroxamates have reached the market, among which is the HDAC inhibitor vorinostat. Failures in development are generally attributed to lack of selectivity, toxicity, or poor stability. To help medicinal chemists with respect to plasma stability, we have performed the first and preliminary study on structure-plasma stability for hydroxamates. We define some structural rules to predict or improve the plasma stability in the preclinical stage.
- Flipo, Marion,Charton, Julie,Hocine, Akila,Dassonneville, Sandrine,Deprez, Benoit,Deprez-Poulain, Rebecca
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experimental part
p. 6790 - 6802
(2010/04/04)
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- Highly efficient selective monohydrolysis of dialkyl malonates and their derivatives
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The highly efficient selective monohydrolysis of symmetric diesters has been applied to monohydrolysis of several dialkyl malonates and their derivatives. The best conditions apply 0.8-1.2 equiv of aqueous KOH with a co-solvent, THF or acetonitrile, at 0 °C. The procedure is highly practical, yielding the corresponding half-esters in high yields in a straightforward manner, without inducing decarboxylation. It was found that the selectivity tends to become higher with increased hydrophobicity.
- Niwayama, Satomi,Cho, Hanjoung,Lin, Chunlei
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p. 4434 - 4436
(2008/12/21)
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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 17-21; 24
(2009/01/24)
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- Malonamide derivatives
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The invention relates to compounds of the formula I wherein R, R1, R2, R3, X, and n are defined in the specification. The invention also provides pharmaceutically suitable acid addition salts thereof and all forms of optically pure enantiomers, recemates or diastereomers and diastereomeric mixtures thereof. Compounds of the invention are useful for the treatment of Alzheimer's disease.
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Page/Page column 10-11
(2010/11/08)
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- Malonamide derivatives
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The invention relates to malonamide derivatives of formula wherein each of the variables are as defined herein and to pharmaceutically acceptable acid addition salts, optically pure enantiomers, racemates and diastereomeric mixtures thereof. These compounds are γ-secretase inhibitors and may be used for the treatment of Alzheimer's disease.
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Page/Page column 10
(2008/06/13)
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- MALONAMIDE DERIVATIVES AS GAMMA-SECRETASE INHIBITORS
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The invention relates to malonamide derivatives of formula (IA) or (IB) and to pharmaceutically suitable acid addition salts thereof. The compounds are γ-secretase inhibitors and the related compounds may be useful in the treatment of Alzheimer's disease.
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- Total synthesis of the amino hip analogue of didemnin A
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Disclosed is a synthetic method for the preparation of analogs of Didemnin A (1), particularly the Amino-Hip analog of Didemnin A, also known as “AipDidemnin A” (8). These compounds have the following structures:
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- Production pyridazine herbicides
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Carboxylic acid ester derivatives of formula (1): wherein R is C1-C6 alkyl, R2 and R3 are independently hydrogen or C1-C3 alkyl, and Q is optionally substituted phenyl, can be easily converted by ring closing into pyridazin-3-one derivatives of formula (7): The carboxylic acids of formula (1) can be produced by reacting hydrazone compounds of formula (5): wherein R3 and Q are as defined above, with malonic acid monoester derivatives of formula (6): wherein R and R2 are as defined above, in the presence of a base.
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- Replacement of glycine with dicarbonyl and related moieties in analogues of the C-terminal pentapeptide of cholecystokinin: CCK2 agonists displaying a novel binding mode
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Recent advances in the field of cholecystokinin have indicated the possible occurrence of multiple affinity states of the CCK2 receptor. Besides, numerous pharmacological experiments performed 'in vitro' and 'in vivo' support the eventuality of different pharmacological profiles associated to CCK2 ligands. Indeed, some agonists are essentially anxiogenic and uneffective in memory tests, whereas others are not anxiogenic and appear as able to reinforce memory. The reference compound for the latter profile is the CCK-8 analogue BC 264 (Boc-Tyr(SO3H)-gNle-mGly-Trp-(NMe)Nle-Asp-Phe-NH2). However, although tetrapeptide ligands based on CCK-4 (Trp-Met-Asp-Phe-NH2) are known to possess sufficient structural features for CCK2 recognition, none shares the properties of BC 264. Hence we have developed new short peptidic or pseud-opeptidic derivatives containing the C-terminal tetrapeptide of BC 264. Our results indicate that some compounds characterized by the presence of two carbonyl groups at the N-terminus, as in 2b (HO2C-CH2-CONH-Trp-(NMe)Nle-Asp-Phe-NH2), are likely to show a BC 264-like profile, bind to the CCK2 receptor in a specific way, and display remarkable affinities (2b: 0.28 nM on guinea-pig cortex membrane preparations). This original binding mode is discussed and further enlightened by NMR and molecular modeling studies.
- Bellier,Million,DaNascimento,Meudal,Kellou,Maigret,Garbay
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p. 3614 - 3623
(2007/10/03)
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- Studies on ambiphilic radicals generated from the ester of N-hydroxy-2-thiopyridone
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Seven different α-carbethoxyalkyl radicals have been generated from Barton esters and their behaviour towards different olefins have been studied to show their philicity.
- Borah,Sarma
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p. 592 - 596
(2007/10/03)
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- Enzymatic enantioselective ester hydrolysis by carboxylesterase NP
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The enzymatic hydrolysis of a series of carboxylic esters by carboxylesterase NP has been investigated in order to determine the scope and limitations of this enzyme. 2-Substituted propionates were hydrolyzed with high enantioselectivity when an aromatic moiety was part of the 2-substituent.Enantioselective hydrolysis could be accomplished with several 2-arypropionates, 2-(aryloxy)propionates and N-arylalanine esters.The propionate esters yielded propionic acids as (S) enantiomers, whereas the alanine esters yielded the (R) enantiomers.Without a 2-aryl substituent, the enzymatic hydrolysis of the propionates occurred at a lower rate without acceptable enantioselectivity.In addition to 2-substituted propionates, only a few other esters were hydrolyzed with high enantioselectivity by carboxylesterase NP, such as some prochiral disubstituted malonates. 1-Phenylethylacetate was the only substrate with chirality in the alcohol part of the ester that was found to be hydrolyzed enantioselectively.Carboxylesterase NP proved to be a powerful enzyme for kinetic resolution of propionate esters with an aromatic ring containing a 2-substituent.
- Smeets, J. W. H.,Kieboom, A. P. G.
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p. 490 - 495
(2007/10/02)
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- Michael Reactions in Aprotic Media. An Effective Method of Construction of α,α,β-Trisubstituted Ketones and Application to Natural Product Synthesis
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By proper selection of the reaction conditions, 1,4-additions of malonate and propionate anions to 2-(phenylthio)-2-cyclopentenone were accomplished.Subsequent trapping of the intermediate enolates with an electrophile in the aprotic media afforded α,α,β-trisubstituted ketones regiospecifically.The effects of the counterion, solvent, and temperature were examined.An application of this method to the formal synthesis of the pseudoguaianolides (+/-)-aromatin and (+/-)-confertin is described.
- Fang, Jim-Min
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p. 3464 - 3470
(2007/10/02)
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