18854-19-8Relevant articles and documents
Isothiourea-Catalyzed Acylative Kinetic Resolution of Tertiary α-Hydroxy Esters
Greenhalgh, Mark D.,Laina-Martín, Víctor,Neyyappadath, Rifahath M.,Qu, Shen,Smith, Andrew D.,Smith, Samuel M.
supporting information, p. 16572 - 16578 (2020/09/09)
A highly enantioselective isothiourea-catalyzed acylative kinetic resolution (KR) of acyclic tertiary alcohols has been developed. Selectivity factors of up to 200 were achieved for the KR of tertiary alcohols bearing an adjacent ester substituent, with both reaction conversion and enantioselectivity found to be sensitive to the steric and electronic environment at the stereogenic tertiary carbinol centre. For more sterically congested alcohols, the use of a recently-developed isoselenourea catalyst was optimal, with equivalent enantioselectivity but higher conversion achieved in comparison to the isothiourea HyperBTM. Diastereomeric acylation transition state models are proposed to rationalize the origins of enantiodiscrimination in this process. This KR procedure was also translated to a continuous-flow process using a polymer-supported variant of the catalyst.
Metal-Free Synthesis of Polysubstituted Imidazolinone Through Cyclization of Amidines with 2-Substituted Acrylates
Liu, Zhen,Zhang, Yan-Shun,Wei, Yin,Shi, Min
supporting information, p. 1093 - 1099 (2020/02/27)
Polysubstituted imidazolinones were synthesized in a facile metal-free cascade nucleophilic cyclization of easily available amidines and 2-substituted acrylates. This protocol is distinguished by simple, mild, and catalyst-free reaction conditions with a broad substrate scope, affording the desired products in moderate to good yields and providing an efficient strategy for synthesis of polysubstituted imidazolinone.
FACTOR XI ACTIVATION INHIBITORS
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Paragraph 26, (2020/12/11)
The present invention provides a compound of Formula (I) and pharmaceutical compositions comprising one or more said compounds, and methods for using said compounds for treating or preventing thromboses, embolisms, hypercoagulability or fibrotic changes. The compounds are selective Factor XI activation inhibitors.
Synthesis of Dihydro-2-oxopyrrole (DPO) Building Blocks Catalyzed by Potassium Carbonate
Zhang, Yan-Shun,Gui, Hou-Ze,Wei, Yin,Shi, Min
supporting information, p. 7179 - 7185 (2019/11/16)
A dimerization and cyclization cascade reaction of 2-sulfonaminoacrylates catalyzed by K2CO3 provides dihydro-2-oxopyrrole (DPO) derivatives. This straightforward and atom-economic transformation features a simple experimental operation with easily available starting materials, a broad substrate scope as well as good functional group tolerance. The desired DPO building blocks are obtained in moderate to good yields.
4,6- O-Pyruvyl Ketal Modified N-Acetylmannosamine of the Secondary Cell Wall Polysaccharide of Bacillus anthracis Is the Anchoring Residue for Its Surface Layer Proteins
Chapman, Robert N.,Liu, Lin,Boons, Geert-Jan
supporting information, p. 17079 - 17085 (2018/12/14)
The secondary cell wall polysaccharide (SCWP) of Bacillus anthracis plays a key role in the organization of the cell envelope of vegetative cells and is intimately involved in host-guest interactions. Genetic studies have indicated that it anchors S-layer and S-layer-associated proteins, which are involved in multiple vital biological functions, to the cell surface of B. anthracis. Phenotypic observations indicate that specific functional groups of the terminal unit of SCWP, including 4,6-O-pyruvyl ketal and acetyl esters, are important for binding of these proteins. These observations are based on genetic manipulations and have not been corroborated by direct binding studies. To address this issue, a synthetic strategy was developed that could provide a range of pyruvylated oligosaccharides derived from B. anthracis SCWP bearing base-labile acetyl esters and free amino groups. The resulting oligosaccharides were used in binding studies with a panel of S-layer and S-layer-associated proteins, which identified structural features of SCWP important for binding. A single pyruvylated ManNAc monosaccharide exhibited strong binding to all proteins, making it a promising structure for S-layer protein manipulation. The acetyl esters and free amine of SCWP did not significantly impact binding, and this observation is contrary to a proposed model in which SCWP acetylation is a prerequisite for association of some but not all S-layer and S-layer-associated proteins.
H8-BINOL chiral imidodiphosphoric acids catalyzed enantioselective synthesis of dihydroindolo-/-pyrrolo[1,2- a ]quinoxalines
Fan, Yan-Sen,Jiang, Yi-Jun,An, Dong,Sha, Di,Antilla, Jon C.,Zhang, Suoqin
supporting information, p. 6112 - 6115 (2015/01/09)
The first enantioselective synthesis of 5,6-dihydroindolo[1,2-a]quinoxalines is achieved by using a newly developed H8-BINOL-type imidodiphosphoric acid catalyst with low catalyst loading through efficient Pictet-Spengler-type reactions of indolyl anilines with ketones. This methodology also generates phenyl-4,5-dihydropyrrolo[1,2-a]quinoxalines with high yields and excellent enantioselectivities. Moreover, this method was utilized to synthesize an HIV-1 inhibitor with high yield and good enantioselectivity through a one-step procedure.
Highly chemo-, enantio-, and regioselective synthesis of α,α-disubstituted furanones by Cu-catalyzed conjugate addition
Endo, Kohei,Yakeishi, Sayuri,Takayama, Ryotaro,Shibata, Takanori
supporting information, p. 8893 - 8897 (2014/07/22)
A highly chemo-, enantio-, and regioselective synthesis of furanones bearing an α,α-disubstituted quaternary stereogenic center is reported. The Cu-catalyzed enantioselective conjugate addition of organoaluminum reagents to unsaturated ketoesters at room temperature and subsequent lactonization took place. Synthetic transformations of furanones represent facile approaches to various cyclic or acyclic compounds bearing a quaternary stereogenic center. Selective chemistry: A highly chemo-, enantio-, and regioselective synthesis of furanones bearing an α,α-disubstituted quaternary stereogenic center is reported (see scheme). Cu-catalyzed enantioselective conjugate addition of organoaluminum reagents to unsaturated ketoesters at room temperature and subsequent lactonization took place.
Polymer-supported tertiary amine in organic synthesis: A useful reagent in the conversion of alkenes to carbonyl compounds via the corresponding ozonides
Hon, Yung-Son,Wu, Kun-Chan
, p. 493 - 498 (2007/10/03)
Polymer-supported tertiary amine 6 is useful to workup the ozonolytic reaction of alkenes. The corresponding carbonyl products can be isolated in excellent yields by simple filtration. For some substituted alkenes, carboxylic acids were formed as the major products and can be isolated from the polymeric resin by washing with 1M HCl followed by extraction with organic solvent. In all cases, simply washing with aqueous NaOH can regenerate the polymeric amine 6. The reactivity of the regenerated polymeric amine is as effective as that of the freshly prepared one.
A highly convenient, efficient, and selective process for preparation of esters and amides from carboxylic acids using Fe3+-K-10 montmorillonite clay
Srinivas,Das, Biswanath
, p. 1165 - 1167 (2007/10/03)
In the presence of Fe3+-K-10 montmorillonite clay as a catalyst, aliphatic carboxylic acids selectively produced the corresponding esters in the presence of aromatic carboxylic acids by treatment with alcohols. Both the aliphatic and aromatic carboxylic acids formed the amides by reacting with the aliphatic amines, but only the aliphatic carboxylic acids yielded the anilides by treatment with aromatic amines. The catalyst is recoverable and recyclable.
A Simple and Efficient Selective Esterification of Aliphatic Carboxylic Acids in the Presence of Aromatic Carboxylic Acids
Das, Biswanath,Venkataiah, B.,Madhusudhan, P.
, p. 59 - 60 (2007/10/03)
Aliphatic carboxylic acids were esterificated selectively at room temperature in the presence of aromatic carboxylic acids by treatment with alcohols in the presence of silica gel supported NaHSO4 catalyst.
