17417-00-4Relevant articles and documents
Synthesis method 2- hydroxyl carboxylic ester (by machine translation)
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Paragraph 0052; 0054; 0055; 0058-0060, (2020/05/05)
The method, is simple 2 - energy consumption, energy consumption is low, the production :(1) of waste water can be greatly reduced, the yield of the target product is high 2 - and the production cost ;(2) is greatly reduced (1). 2 - The method comprises the following steps, preparing 2 - hydroxycarboxylate, with an acid ;(3) by a byproduct ammonium salt (2) in step, and filtering the excess acid, to remove the byproduct ammonium salt, to obtain 2 - hydroxyl carboxylic acid ester product, by esterification reaction in step (, and filtering to remove 2 - the excess, alcohol), from, the reaction, solution obtained by the reaction solution; of the catalyst under the, action of, a catalyst, to obtain the product of the compound. (by machine translation)
PROCESS OF PRODUCING ALPHA-HYDROXY COMPOUNDS AND USES THEREOF
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Page/Page column 16-19, (2019/08/29)
New process of producing alpha-hydroxy compounds from sustainable resources useful as platform chemicals, such as hydroxy analogues of amino acids or polymer precursors.
Ru-MACHO-Catalyzed Highly Chemoselective Hydrogenation of α-Keto Esters to 1,2-Diols or α-Hydroxy Esters
Gao, Shaochan,Tang, Weijun,Zhang, Minghui,Wang, Chao,Xiao, Jianliang
supporting information, p. 1748 - 1752 (2016/07/06)
A ruthenium pincer catalyst has been shown to be highly effective for the hydrogenation of a wide range of α-keto esters, affording either diols or hydroxy esters depending on the choice of reaction conditions. Strong base, high temperature, and pressure favor the formation of diols whilst the opposite is true for the hydroxy esters.
Chiral propargylic cations as intermediates in SN1-type reactions: Substitution pattern, nuclear magnetic resonance studies, and origin of the diastereoselectivity
Nitsch, Dominik,Huber, Stefan M.,Poethig, Alexander,Narayanan, Arjun,Olah, George A.,Prakash, G. K. Surya,Bach, Thorsten
supporting information, p. 2851 - 2857 (2014/03/21)
Nine propargylic acetates, bearing a stereogenic center (-C*HXR 2) adjacent to the electrophilic carbon atom, were prepared and subjected to SN1-type substitution reactions with various silyl nucleophiles employing bismuth trifluoromethanesulfonate [Bi(OTf)3] as the Lewis acid. The diastereoselectivity of the reactions was high when the alkyl group R2 was tertiary (tert-butyl), irrespective of the substituent X. Products were formed consistently with a diastereomeric ratio larger than 95:5 in favor of the anti-diastereoisomer. If the alkyl substitutent R2 was secondary, the diastereoselectivity decreased to 80:20. The reaction was shown to proceed stereoconvergently, and the relative product configuration was elucidated. The reaction outcome is explained by invoking a chiral propargylic cation as an intermediate, which is preferentially attacked by the nucleophile from one of its two diastereotopic faces. Density functional theory (DFT) calculations suggest a preferred conformation in which the group R2 is almost perpendicular to the plane defined by the three substituents at the cationic center, with the nucleophile approaching the electrophilic center opposite to R2. Transition states calculated for the reaction of allyltrimethylsilane with two representative cations support this hypothesis. Tertiary propargylic cations with a stereogenic center (-C* HXR2) in the α position were generated by ionization of the respective alcohol precursors with FSO3H in SO2ClF at -80 C. Nuclear magnetic resonance (NMR) spectra were obtained for five cations, and the chemical shifts could be unambiguously assigned. The preferred conformation of the cations as extracted from nuclear Overhauser experiments is in line with the preferred conformation responsible for the reaction of the secondary propargylic cations.
The scent of bacteria: Headspace analysis for the discovery of natural products
Citron, Christian A.,Rabe, Patrick,Dickschat, Jeroen S.
supporting information, p. 1765 - 1776 (2013/01/15)
Volatile compounds released by 50 bacterial strains, 45 of them actinobacteria in addition to three chloroflexi and two myxobacteria, have been collected by use of a closed-loop stripping apparatus, and the obtained headspace extracts have been analyzed by GC-MS. Excluding terpenes that have recently been published elsewhere, 254 compounds from all kinds of compound classes have been identified. For unambiguous compound identification several reference compounds have been synthesized. Among the detected volatiles 12 new natural products have been found, in addition to mellein, which was released by Saccharopolyspora erythraea. The iterative PKS for this compound has recently been identified by in vitro experiments, but mellein production in S. erythraea has never been reported before. These examples demonstrate that headspace analysis is an important tool for the discovery of natural products that may be overlooked using conventional techniques. The method is also useful for feeding experiments with isotopically labeled precursors and was applied to investigate the biosynthesis of the unusual nitrogen compound 1-nitro-2-methylpropane, which arises from valine. Furthermore, several streptomycetes emitted compounds that were previously recognized as insect pheromones, thus questioning if bacterial symbionts are involved in insect communication.
A new class of versatile chiral-bridged atropisomeric diphosphine ligands: Remarkably efficient ligand syntheses and their applications in highly enantioselective hydrogenation reactions
Qiu, Liqin,Kwong, Fuk Yee,Wu, Jing,Lam, Wai Har,Chan, Shusun,Yu, Wing-Yiu,Li, Yue-Ming,Guo, Rongwei,Zhou, Zhongyuan,Chan, Albert S. C.
, p. 5955 - 5965 (2007/10/03)
A series of chiral diphosphine ligands denoted as PQ-Phos was prepared by atropdiastereoselective Ullmann coupling and ring-closure reactions. The Ullmann coupling reaction of the biaryl diphosphine dioxides is featured by highly efficient central-to-axial chirality transfer with diastereomeric excess >99%. This substrate-directed diastereomeric biaryl coupling reaction is unprecedented for the preparation of chiral diphosphine dioxides, and our method precludes the tedious resolution procedures usually required for preparing enantiomerically pure diphosphine ligands. The effect of chiral recognition was also revealed in a relevant asymmetric ring-closure reaction. The chiral tether bridging the two aryl units creates a conformationally rigid scaffold essential for enantiofacial differentiation; fine-tuning of the ligand scaffold (e.g., dihedral angles) can be achieved by varying the chain length of the chiral tether. The enantiomerically pure Ru- and Ir-PQ-Phos complexes have been prepared and applied to the catalytic enantioselective hydrogenations of α- and β-ketoesters (C=O bond reduction), 2-(6′-methoxy- 2′-naphthyl)-propenoic acid, alkyl-substituted β-dehydroamino acids (C=C bond reduction), and N-heteroaromatic compounds (C=N bond reduction). An excellent level of enantioselection (up to 99.9% ee) has been attained for the catalytic reactions. In addition, the significant ligand dihedral angle effects on the Ir-catalyzed asymmetric hydrogenation of N-heteroaromatic compounds were also revealed.
AMINO HETEROCYCLIC MODULATORS OF CHEMOKINE RECEPTOR ACTIVITY
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Page/Page column 42, (2010/02/13)
Compounds of Formula I and Formula II: (wherein n, R 1,R2, R3, R4, R5, R6, R7, R8, R9, R10, R15, R16, R17, R18, R19, R24, R25, R26, R27, R28, R29, R30, R33 R34, R35, R36, R37, R38, A, j, k, m, n, X, Y and Z are as defined herein) which are modulators of chemokine receptor activity and are useful in the prevention or treatment of certain inflammatory and immunoregulatory disorders and diseases, allergic diseases, atopic conditions including allergic rhinitis, dermatitis, conjunctivitis, and asthma, as well as autoimmune pathologies such as rheumatoid arthritis and atherosclerosis. The invention is also directed to pharmaceutical compositions comprising these compounds and the use of these compounds and compositions in the prevention or treatment of such diseases in which chemokine receptors are involved.
Enantioselectivity of Pseudomonas cepacia lipase for the acetylation of 2-hydroxy carboxylic acid esters+
Sundholm, Oskari,Kanerva, Liisa T.
, p. 625 - 640 (2007/10/03)
Structurally different ethyl or methyl 2-hydroxy carboxylates were resolved by Pseudomonas cepacia lipase-catalysed acetylations with vinyl acetate in diethylether. One type of the alcoholic substrates (2-hydroxy-2-arylacetates and 2-hydroxy-3-arylpropinates) contained a HO-group at the stereocentre. These compounds were resolved with high enantioselectivity (ee 91 → 99) at ca. 50% conversion. The other alcoholic substrates ((threo-2-hydroxy-3-methylbutyrate and threo- or erythro-2-hydroxy-3-aryl-3-arylthio(or aryloxy)propionates) with two stereocentres generally resulted in enantiopure products and the reactions stopped at 50 % conversion.
Stereoselective Bromination of Dehydroamino Acids with Controllable Retention or Inversion of Olefin Configuration
Coleman, Robert S.
, p. 4452 - 4461 (2007/10/02)
Dehydroamino acids react with brominating reagents to produce syn-α-bromo imines as the major products, which undergo tautomerization to mixtures of the diastereomeric (E)- and (Z)-β-bromo-α,β-dehydroamino acids upon treatment with base.Herein, we examine
A SYNTHON FOR CHIRAL GLYCOLATE ENOLATE (ROC-HCOOR'): A CAMPHOR-BASED OXAZOLINE
Kelly, T. Ross,Arvanitis, Argyrios
, p. 39 - 42 (2007/10/02)
Alkylations of the anion (7a) derived from a camphor-based oxazoline proceed in good yield.Hydrolysis affords the corresponding α-hydroxy acids in high ee.
