1003-83-4Relevant articles and documents
Asymmetric microbial hydrolysis of epoxides
Mischitz,Kroutil,Wandel,Faber
, p. 1261 - 1272 (1995)
Kinetic resolution of 2-mono- and 2,2-disubstituted epoxides was accomplished using epoxide hydrolases from bacterial and fungal origin by employing lyophilized whole microbial cells. In all cases investigated, the biocatalytic hydrolysis was shown to proceed with retention of configuration at the stereogenic center leading to 1,2-diols and remaining epoxides. The selectivity of the reaction was dependent on the substrate structure and the strain used with E-values ranging from low or moderate (with 2-monosubstituted epoxides) to excellent (E >100, with 2,2-disubstituted oxiranes).
Mechanically Gated Degradable Polymers
Lin, Yangju,Kouznetsova, Tatiana B.,Craig, Stephen L.
, p. 2105 - 2109 (2020)
Degradable polymers are desirable for the replacement of conventional organic polymers that persist in the environment, but they often suffer from the unintentional scission of the degradable functionalities on the polymer backbone, which diminishes polymer properties during storage and regular use. Herein, we report a strategy that combats unintended degradation in polymers by combining two common degradation stimuli - mechanical and acid triggers - in an "AND gate" fashion. A cyclobutane (CB) mechanophore is used as a mechanical gate to regulate an acid-sensitive ketal that has been widely employed in acid degradable polymers. This gated ketal is further incorporated into the polymer backbone. In the presence of an acid trigger alone, the pristine polymer retains its backbone integrity, and delivering high mechanical forces alone by ultrasonication degrades the polymer to an apparent limiting molecular weight of 28 kDa. The sequential treatment of ultrasonication followed by acid, however, leads to a further 11-fold decrease in molecular weight to 2.5 kDa. Experimental and computational evidence further indicate that the ungated ketal possesses mechanical strength that is commensurate with the conventional polymer backbones. Single molecule force spectroscopy (SMFS) reveals that the force necessary to activate the CB molecular gate on the time scale of 100 ms is approximately 2 nN.
The synthesis of the 2, 3-difluorobutan-1, 4-diol diastereomers
Szpera, Robert,Kovalenko, Nadia,Natarajan, Kalaiselvi,Paillard, Nina,Linclau, Bruno
, p. 2883 - 2887 (2017)
The diastereoselective synthesis of fluorinated building blocks that contain chiral fluorine substituents is of interest. Here we describe optimisation efforts in the synthesis of anti-2, 3-difluorobutane-1, 4-diol, as well as the synthesis of the corresponding syn-diastereomer. Both targets were synthesised using an epoxide opening strategy.
Nickel mdiated Double Bond formation from vic-Dibromides and Ethyl Magnesium Bromide
Malanga, Corrado,Aronica, Laura A.,Lardicci, Luciano
, p. 9189 - 9192 (1995)
vic-dibromides are quantitaively converted into alkenes by using a catalityc amount of NidppeCl2 in the presence of two molar equivalents of EtMgBr in THF.Stereochemical aspects of the reaction are given.
Preparation process method of gadobutrol epoxy side chain intermediate
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Paragraph 0070-0079; 0090-0098; 0129-0136, (2017/08/29)
The invention disclose a 4,4-dimethyl 3,5,8-trioxabic [5,1,0]ycloctane and particularly relates to a preparation process method of a gadobutrol epoxy side chain intermediate. According to the preparation process method disclosed by the invention, by adjusting the weight ratio of feeding materials, optimizing reaction conditions and improving post treatment and purification methods, the impurity content of an obtained gadobutrol epoxy side chain intermediate product is low; the quality of the intermediate product is greatly improved while the yield is increased, so that the difficulty of process control of the gadobutrol crude drugs during the production process is reduced, and the quality and the qualification rate of the gadobutrol crude drugs are improved. The preparation process method disclosed by the invention has the advantages of simple operation methods in all process steps, safe and feasible solvent and technological conditions, realization of green and environmental-friendly production and wide application prospect.
Further synthetic attempts towards calicene
Al-Dulayymi, Ahmad,Li, Xiaoming,Neuenschwander, Markus
, p. 1633 - 1644 (2007/10/03)
First synthetic attempts towards the so-far-unknown calicene (= 5- (cycloprop-2-en-1-ylidene)cyclopenta-1,3-diene) precursors 3-(cyclopenta-2,4- dien-1-ylidene)tricyclo[3.2.2.22.4]nona-6,8-diene (4; Scheme 1), 1,4- di(cyclopenta-2,4-dien-1-ylid
Process for producing amide derivatives and intermediates therefor
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, (2008/06/13)
PCT No. PCT/JP96/02756 Sec. 371 Date Apr. 14, 1998 Sec. 102(e) Date Apr. 14, 1998 PCT Filed Sep. 24, 1996 PCT Pub. No. WO97/11937 PCT Pub. Date Apr. 3, 1997A method for producing an amide derivative of the formula [XV] wherein each symbol is as defined in the specification, and an enantiomer thereof, a novel intermediate useful for producing said compound and a production method thereof. The production method of the present invention is extremely easy and simple as compared to the conventional methods, and enables effective production of compound [XV] at high yields, which includes compound [XVI] having an HIV protease inhibitory action. In addition, the novel intermediates of the present invention are extremely useful as intermediates for producing not only the aforementioned compound [XVI] but also compounds useful as X-ray contrast media.
Production of amide derivatives and intermediate compounds therefor
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, (2008/06/13)
A method for producing an amide derivative of the formula ?XV! STR1 wherein each symbol is as defined in the specification, and an enantiomer thereof, a novel intermediate useful for producing said compound and a production method thereof. The production method of the present invention is extremely easy and simple as compared to the conventional methods, and enables effective production of compound ?XV! at high yields, which includes compound ?XVI! having an HIV protease inhibitory action. In addition, the novel intermediates of the present invention are extremely useful as intermediates for producing not only the aforementioned compound ?XVI! but also compounds useful as X-ray contrast media.
Cyclisation of 2-Substituted 2-Bromomethyl-1,3-dioxacyclohept-5-enes; Hydrogen Transfer Reactions of 1,3-Dioxacyclohept-5-enes and 1,3-Dithiacyclohept-5-enes
Hindson, Andrew C.,MacCorquodale, Finlay,Walton, John C.
, p. 871 - 877 (2007/10/02)
2-Bromomethyl-1,3-dioxacyclohept-5-enes (2-bromomethyl-4,7-dihydro-1,3-dioxepins), containing an additional substituent at the 2-position, cyclise to afford 1-substituted 2,7-dioxabicyclooctanes on treatment with tributyltin hydride.The rate constants for cyclisation of the 2-methyl- and 2-phenyl-4,7-dihydro-1,3-dioxepin-2-ylmethyl radicals are 8.4 * 105 and 4.9 * 105 s-1 respectively at 298 K.Hydrogen is readily abstracted from the 4- and 7-positions of 4,7-dihydro-1,3-dioxepins by tert-butoxyl radicals to give 4,7-dihydro-1,3-dioxepin-4-yl radicals which have been characterised by EPR spectroscopy.The Arrhenius parameters for inversion of the 'flap' conformers have been determined from the exchange-broadened spectra of the 2,2-dimethyl and 2,2-diethyl radicals.The analogous radicals, expected on hydrogen abstraction from 1,3-dithiacyclohept-5-enes (4,7-dihydro-1,3-dithiepins), cannot be spectroscopically observed.Instead, the same spectrum, which we attribute to a degradation intermediate, is obtained from a series of 2,2-dialkyl-4,7-dihydro-1,3-dithiepins.