29569-79-7Relevant academic research and scientific papers
Investigation of Electrostatic Interactions towards Controlling Silylation-Based Kinetic Resolutions
Zhang, Tian,Redden, Brandon K.,Wiskur, Sheryl L.
supporting information, p. 4827 - 4831 (2019/08/12)
Electrostatic interactions between a silylated isothiourea intermediate and an ester π system were explored by determining how variations in sterics and electronics affect the selectivity of a silylation-based kinetic resolution. Sterics on the π systems affect the selectivity factors of alkyl 2-hydroxycyclohexanecarboxylates, resulting in a strong correlation of selectivity factors to Charton values. Induction effects of electron-withdrawing substituents on phenyl esters significantly enhance selectivity supporting an edge to face π–π interaction. The linear free energy relationships that were uncovered will aid in future incorporation of intermolecular electrostatic interactions towards controlling asymmetric reactions.
Chemoenzymatic approaches to the synthesis of the (1S,2R)-isomer of benzyl 2-hydroxycyclohexanecarboxylate
Tsunekawa, Ryuji,Hanaya, Kengo,Higashibayashi, Shuhei,Shoji, Mitsuru,Sugai, Takeshi
, p. 84 - 89 (2017/12/06)
We examined ten strains of cultured whole-cell yeasts for the asymmetric reduction of commercially available ethyl 2-oxocyclohexanecarboxylate, and found that the (1S,2S)-stereoisomer of ethyl 2-hydroxycyclohexanecarboxylate was the major stereoisomer produced by Williopsis californica JCM 3600. The ethyl group of the ester was then substituted with a benzyl group with low volatility and increased hydrophobicity to facilitate the isolation of the expected product. Incubation with W. californica furnished benzyl (1S,2S)-2-hydroxycyclohexanecarboxylate (>99.9% ee) in 51.0% yield together with its (1R,2S)-isomer (>99.9% ee) in 35.4% yield. Upon treatment of the same substrate bearing the benzyl ester with a screening kit of purified overexpressed carbonyl reductases (Daicel Chiralscreen OH), two enzymes (E031, E078) furnished the (1R,2S)-isomer as the major product. With another enzyme (E007), the (1S,2R)-isomer was obtained, but its ee was very low (25.6%). The highly enantiomerically enriched (1S,2S)-isomer obtained by W. californica was transformed to the (1S,2R)-isomer (>99.9% ee), whose availability until now has been low, in 43.3% yield over two steps involving tosylation and subsequent inversive attack with tetrabutylammonium nitrite.
BIARYL PYRAZOLES AS NRF2 REGULATORS
-
Page/Page column 455, (2017/08/01)
The present invention relates to biaryl pyrazole compounds, methods of making them, pharmaceutical compositions containing them and their use as NRF2 regulators.
New Route to Stabilize Ruthenium Nanoparticles with Non-Isolable Chiral N-Heterocyclic Carbenes
Martnez-Prieto, Luis Miguel,Ferry, Anglique,Lara, Patricia,Richter, Christian,Philippot, Karine,Glorius, Frank,Chaudret, Bruno
, p. 17495 - 17502 (2016/01/25)
Ru nanoparticles (RuNPs) stabilized by non-isolable chiral N-heterocyclic carbenes (NHCs), namely SIDPhNp ((4S,5S)-1,3-di(naphthalen-1-yl)-4,5-diphenylimidazolidine) and SIPhOH ((S)-3-((1S,2R)-2-hydroxy-1,2-diphenylethyl)-1-((R)-2-hydroxy-1,2-diphenylethyl)-4,5-dihydro-3H-imidazoline), have been synthesized through a new procedure that does not require isolation of the free carbenes. The obtained RuNPs have been characterized by state-of-the-art techniques and their surface chemistry has been investigated by FTIR and solid-state MAS NMR upon the coordination of CO, which indicated the presence of free and reactive Ru sites. Their catalytic activity has been tested in various hydrogenation reactions involving competition between different sites, whereby interesting differences in selectivity were observed, but no enantioselectivity.
Enantioselective ketoester reductions in water: A comparison between microorganism-and ruthenium-catalyzed reactions
Zeror, Saoussen,Collin, Jacqueline,Fiaud, Jean-Claude,Zouioueche, Louisa Aribi
experimental part, p. 1211 - 1215 (2010/10/20)
In the search for green chemistry methods for the enantioselective reduction of ketoesters Saccharomyces cerevisiae-and ruthenium-catalyzed reactions in water have been investigated. The highest enantiomeric excesses for the reduction of α-and β-ketoesters have been obtained by S. cerevisiae. Chiral ruthenium catalysts are active for the reduction of all ketoesters with low to moderate enantioselectivities depending on the nature of the substrate and ligand. Interestingly, for several substrates both enantiomers of the hydroxyesters have been obtained according either to the catalytic method or to the structure of the ligand.
Synthesis and characterization of the enantiomerically pure cis- and trans-2,4-dioxa-3-fluoro-3-phosphadecalins as inhibitors of acetylcholinesterase
Waechter, Michael,Rueedi, Peter
experimental part, p. 283 - 294 (2010/04/23)
The title compounds, the P(3)-axially- and P(3)-equatorially-substituted cis- and trans-configured 3-fluoro-2,4-dioxa-3-phosphadecalin 3-oxides (= 3-fluoro-2,4-dioxa-3-phosphabicyclo[4.4.0]decane 3-oxides) have been prepared (ee > 99%) and fully character
Effects of methyl substituents on the activity and enantioselectivity of homobenzotetramisole-based catalysts in the kinetic resolution of alcohols
Zhang, Yuhua,Birman, Vladimir B.
supporting information; scheme or table, p. 2525 - 2529 (2009/12/28)
Substitution of the tetrahydropyrimidine ring in the enantioselective acyl transfer catalyst homobenzotetramisole (HBTM) 6 with methyl groups exerts a dramatic influence on its performance in the kinetic resolution of secondary alcohols. The syn-3-methyl analogue of HBTM (9a) has proved to be superior to the parent compound in terms of catalytic activity, enantioselectivity, and synthetic accessibility.
Homobenzotetramisole: An effective catalyst for kinetic resolution of aryl-cycloalkanols
Birman, Vladimir B.,Li, Ximin
supporting information; experimental part, p. 1115 - 1118 (2009/04/07)
Homobenzotetramisole (HBTM), a ring-expanded analogue of the previously reported catalyst BTM, displays higher catalytic activity and a different structure-selectivity profile. It displays good enantioselectivities in kinetic resolution of secondary benzylic alcohols but is particularly effective for 2-aryl-substituted cycloalkanols.
Carbonylative ring opening of terminal epoxides at atmospheric pressure
Denmark, Scott E.,Ahmad, Moballigh
, p. 9630 - 9634 (2008/03/17)
(Chemical Equation Presented) The carbonylative opening of terminal epoxides under mild conditions has been developed using Co2-(CO) 8 as the catalyst. Under 1 atm of carbon monoxide and at room temperature in methanol, propylene oxide is converted to methyl 3-hydroxybutanoate in up to 89% yield. This transformation is general for many terminal epoxides bearing alkyl, alkenyl, aryl, alkoxy, chloromethyl, phthalimido, and acetal functional groups. The opening takes place without epimerization at the secondary stereocenter.
Reductions of cyclic β-keto esters by individual Saccharomyces cerevisiae dehydrogenases and a chemo-enzymatic route to (1R,2S)-2-methyl-1-cyclohexanol
Padhi, Santosh Kumar,Kaluzna, Iwona A.,Buisson, Didier,Azerad, Robert,Stewart, Jon D.
, p. 2133 - 2138 (2008/02/11)
Twenty purified dehydrogenases cloned from bakers' yeast (Saccharomyces cerevisiae) and expressed as fusion proteins with glutathione (S)-transferase were tested for their ability to reduce three homologous cyclic β-keto esters. The majority of dehydrogenases reduced ethyl 2-oxo-cyclopentanecarboxylate, yielding a pair of diastereomeric alcohols with consistent (1R)-stereochemistry. Ethyl 2-oxo-cyclohexanecarboxylate reductions afforded only cis-alcohol enantiomers. Ethyl 2-oxo-cycloheptanecarboxylate was accepted by two enzymes in the collection, and both yielded mainly the cis-(1R,2S)-alcohol. Escherichia coli cells overexpressing the YDL124w gene were used in a dynamic kinetic resolution of ethyl 2-oxo-cyclohexanecarboxylate to produce the key intermediate in a chemo-enzymatic synthesis of (1R,2S)-2-methyl-1-cyclohexanol, an important chiral building block.
