1655-06-7Relevant articles and documents
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
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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.
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
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.
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.
Rhodium-catalyzed reformatsky-type reaction
Kanai, Kazuo,Wakabayashi, Hitoshi,Honda, Toshio
, p. 2549 - 2551 (2007/10/03)
(equation presented) A novel Reformatsky-type reaction was developed using RhCl(PPh3)3 and diethylzinc. Inter- and intramolecular Reformatsky-type reactions were achieved efficiently under mild reaction conditions to give β-hydroxy esters.
Stereoselective synthesis of novel anti-MRSA tricyclic carbapenems (trinems)
Kanno, Osamu,Kawamoto, Isao
, p. 5639 - 5648 (2007/10/03)
(4S)-Hydroxymethyltrinem 3 was prepared via stereoselective aldol-type reaction with optically pure (R)-2-t-butyldimethylsilyloxymethylcyclohexanone ((R)-16). (4S)-Hydroxymethyltrinem 3 was converted into various kinds of trinem derivatives with anti-MRSA activity by using the Mitsunobu reaction. (C) 2000 Elsevier Science Ltd.
BENZAMIDINE DERIVATIVES SUBSTITUTED BY CYCLIC AMINO ACID AND CYCLIC HYDROXY ACID DERIVATIVES AND THEIR USE AS ANTI-COAGULANTS
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, (2008/06/13)
This invention is directed to benzamidine derivatives substituted by cyclic amino acid and cyclic hydroxy acid derivatives which are useful as anti-coagulants. This invention is also directed to pharmaceutical compositions containing the compounds of the invention, and methods of using the compounds to treat disease-states characterized by thrombotic activity.
