64520-58-7Relevant academic research and scientific papers
Diastereoface Selectivity During Phthalimidonitrene Additions to (E)- and (Z)-Configurated α,β-Unsaturated Esters, Induced by a Chiral Center in the γ-Position
Chilmonczyk, Zdzislaw,Egli, Markus,Behringer, Christoph,Dreiding, Andre S.
, p. 1095 - 1106 (1989)
In-situ-generated phthalimidonitrene was added to five α,β-unsaturated esters containing a chiral secondary O-function at C(γ).The additions were fully suprafacial, inasmuch as the (E)-isomers 1 afforded only the trans-aziridines 2 and 3 (J(β,γ)=4.8-5.1 Hz) and the (Z)-isomers 4 only the cis-aziridines 5 and 6 (8.2-8.5 Hz).The products 2, 3, 5, and 6 where shown to possess the arabino-, xylo-, ribo-, and lyxo-configuration, respectively, by X-ray structure analysis of 2b, 2d, and 6a.The diastereoface selectivity of the nitrene addition, induced by the chiral substructure around C(γ), resulted in more 2 than 3 from 1, but more 6 than 5 from 4, which means that the preference of attack at the double bond switches from one side to the other depending on the C=C configuration.The preferences were higher at lower temperature.The aziridines 2a, 2d, and 3d exhibit 1H-NMR-visible isomerism at the ring N-atom; the major (78-95percent) invertomer A is always the one with the phthalimido group in trans-position to the (larger) substructure around C(γ).The other aziridines only show 1H-NMR signals of one invertomer, which - by steric reasoning - ought to be A; this is confirmed by a 1H-NMR argument for 3a, 5a, 6a, 5c, and 6c.
MONOBACTAM COMPOUNDS AND USE THEREFOR
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, (2022/01/12)
Monobactam compounds and a use therefor. Specifically provided are chemical compounds represented by formula (I) or isomers, pharmaceutically acceptable salts, solvates, crystals, or prodrugs thereof, preparation methods therefor, pharmaceutical compositions containing said compounds, and a use of said compounds or compositions in treating bacterial infection. The present compounds feature excellent antibacterial activity, and have great hopes of becoming a therapeutic agent for bacterial infection.
Stereocontrolled Synthesis of Tetrafluoropentanols: Multivicinal Fluorinated Alkane Units for Drug Discovery
Bentler, Patrick,Erdeljac, Nathalie,Bussmann, Kathrin,Ahlqvist, Marie,Knerr, Laurent,Bergander, Klaus,Daniliuc, Constantin G.,Gilmour, Ryan
, p. 7741 - 7745 (2019/09/03)
A stereodivergent synthesis of four diastereomeric 2,3,4,5-tetrafluoropentanols is disclosed. X-ray crystallographic analysis reveals conformations that manifest sequential stereoelectronic gauche effects (σC-H/C → σC-F*), thereby generating topological diversity via subtle C(sp3)-H to C(sp3)-F exchange. Two representative tetrafluoro arrays have been incorporated into truncated analogues of Gilenya for the management of relapsing remitting multiple sclerosis. These closely similar multivicinal fluoroalkanes have notably different physicochemical profiles and were found to be stable in the presence of human microsomes.
Stereoselective synthesis and antiproliferative activity of the isomeric sphinganine analogues
?onková, Miroslava,Martinková, Miroslava,Gonda, Jozef,Jacková, Dominika,Pilátová, Martina Bago,Kupka, Daniel,Jáger, Dávid
, p. 76 - 85 (2018/12/11)
A flexible synthetic approach to biologically active sphingoid base-like compounds with a 3-amino-1,2-diol framework was achieved through a [3,3]-sigmatropic rearrangement and late stage olefin cross-metathesis as the key transformations. The stereochemistry of the newly created stereogenic centre was assigned via a single crystal X-ray analysis of the (4S,5R)-5-(hydroxymethyl)-4-vinyloxazolidine-2-thione. In order to rationalise the observed stereoselectivity of the aza-Claisen rearrangement, DFT calculations were carried out. The targeted isomeric sphingoid bases were screened in vitro for anticancer activity on a panel of seven human malignant cell lines. Cell viability experiments revealed that C17-homologues are more active than their C12 congeners.
Assignment of the relative and absolute stereochemistry of two novel epoxides using NMR and DFT-GIAO calculations
Moraes,Alvarenga,Demuner,Viana
, p. 109 - 115 (2018/05/03)
Considering the potential biological application of isobenzofuranones, especially as agrochemical defensives, two novel epoxides, (1aR,2R,2aR,5S,5aS,6S,6aS)-5-(hydroxymethyl)hexahydro-2,6-methanooxireno[2,3-f]isobenzofuran-3(1aH)-one (9), and (1aS,2S,2aR,5S,5aS,6R,6aR)-5-(hydroxymethyl)hexahydro-2,6-methanooxireno[2,3-f]isobenzofuran-3(1aH)-one (10), were synthesized from the readily available D-mannitol in six steps. The multiplicities of the hydrogens located at the bridge of the bicycle are distinct for epoxides 9 and 10 due to W coupling, and this feature was employed to confirm the assignment of these nuclei. Besides analyses of the 2D NMR spectra, the assignments of the nuclei at the epoxide ring were also inferred from information obtained by theoretical calculations. The calculated 1H and 13C NMR chemical shifts for eight candidate structures were compared with the experimental chemical shifts of 9 and 10 by measuring the mean absolute errors (MAE) and by the DP4 statistical analysis. The structures and relative configurations of 9, and 10 were determined via NMR spectroscopy assisted with theoretical calculations. As consequence of the enantioselective syntheses starting from a natural polyol, the absolute configurations of the epoxides 9 and 10 were also defined.
Stereoselective formal synthesis of (-)-fumagillol
Raghavan, Sadagopan,Yelleni, Mahesh Kumar Rao
, p. 4371 - 4379 (2017/07/03)
A formal synthesis of fumagillol, a congener of fumagillin that possesses varied biological activity, is disclosed. Initial attempts at preparing an allylic sulfide via an α-chloro sulfide met with failure. The successful route involves a carbonyl-ene reaction, one-pot stannyl cupration, methylation of resulting alkenyl copper and further Stille-coupling of the alkenyl stannane as the key steps.
PROCESSES FOR PREPARING 2-DIHALO RIBOLACTONES
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Page/Page column 83; 84; 92; 93, (2017/06/21)
Methods for forming 2-bromo, 2-fluoro ribofuranose intermediates and 2-chloro, 2- fluoro ribofuranose intermediates for use in preparing antiviral nucleosides are disclosed. Methods for forming nucleosides, and nucleoside prodrugs, using the intermediates, are also disclosed. The methods all produce intermediates, and the resulting nucleosides and prodrugs thereof, wherein the chirality of the carbon at the 2-position is controlled. In some embodiments, the chemistry involves using chiral auxiliaries, such as (R)-2,2-dimethyl-l,3- dioxolane-4-carbaldehyde, and in other embodiments, the chemistry involves using chiral starting materials, such as D-xylose.
PROCESS FOR THE PREPARATION OF [(1 S,2R)-3-[[(4-AMINOPHENYL)SULFONYL] (2-METHYLPROPYL)AMINO]-2-HYDROXY-1 -(PHENYLMETHYL)PROPYL]-CARBAMIC ACID (3R,3AS,6AR)HEXAHYDRO FURO[2,3-B]FURAN-3-YL ESTER AND ITS AMORPHOUS FORM
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, (2017/04/21)
The present invention relates to an improved process for the preparation of [(1 S,2R)-3-[ [(4-aminophenyl)sulfonyl] (2-methylpropyl)amino]-2-hydroxy- 1 -(phenylmethyl)propyl] - carbamic acid (3R,3aS,6aR)hexahydrofuro[2,3-b]furan-3-yl ester compound of formula- 1 represented by the following structural formula:
Formal synthesis of nanaomycin D via a Hauser-Kraus annulation using a chiral enone-lactone
Hassan, Najmah P.S.,Naysmith, Briar J.,Sperry, Jonathan,Brimble, Margaret A.
, p. 7137 - 7143 (2015/08/24)
Abstract A formal total synthesis of nanaomycin D has been achieved. The strategy employed made use of a one-pot cyclisation-stereoselective reduction of a hydroxyketone to install the pyranonaphthalene moiety after execution of a Hauser-Kraus annulation using a chiral enone-lactone as the Michael acceptor to append the γ-lactone ring. The chirality in the chiral enone-lactone was established using a Sharpless asymmetric dihydroxylation. The enone-lactone used herein represents an attractive chiral synthon for the construction of other γ-lactone containing pyranonaphthoquinones such as griseusin A and crisamicin A.
Reversal of facial selectivity in a thia-Claisen rearrangement by incorporation of a vinylic bromine substituent
Ellwood, Adam R.,Mortimer, Anne J. Price,Goodman, Jonathan M.,Porter, Michael J.
, p. 7530 - 7539 (2013/11/06)
Thia-Claisen rearrangements have been carried out using N-benzylpyrrolidine-2-thione and chiral allylic bromides derived from d-mannitol. Introduction of a bromine atom onto the double bond of the allylic bromide reverses the sense of diastereoselectivity in the [3,3]-sigmatropic rearrangement. Density functional theory calculations lead us to rationalise the observed selectivity in terms of a Cieplak effect.
