- Solvent-freeN-Boc deprotection byex situgeneration of hydrogen chloride gas
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An efficient, scalable and sustainable method for the quantitative deprotection of thetert-butyl carbamate (N-Boc) protecting group is described, using down to near-stoichiometric amounts of hydrogen chloride gas in solvent-free conditions. We demonstrate theex situgeneration of hydrogen chloride gas from sodium chloride and sulfuric acid in a two-chamber reactor, introducing a straightforward method for controlled and stoichiometric release of HCl gas. The solvent-free conditions allow deprotection of a wide variety ofN-Boc derivatives to obtain the hydrochloride salts in quantitative yields. The procedure obviates the need for any work-up or purification steps providing an uncomplicated green alternative to standard methods. Due to the solvent-free, anhydrous conditions, this method shows high tolerance towards acid sensitive functional groups and furnishes expanded functional group orthogonality.
- De Borggraeve, Wim M.,Gilles, Philippe,Van Mileghem, Seger,Verschueren, Rik H.
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supporting information
p. 5782 - 5787
(2021/07/12)
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- L-serine linked dihydroartemisinin-fluoroquinolone conjugate and intermediate thereof, preparation methods of L-serine linked dihydroartemisinin-fluoroquinolone conjugate and intermediate thereof, and uses of L-serine linked dihydroartemisinin-fluoroquinolone conjugate
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The invention discloses an L-serine linked dihydroartemisinin-fluoroquinolone conjugate represented by a formula I, an intermediate represented by a formula II, preparation methods of the compounds represented by the formula I and the formula II, and uses of the compound represented by the formula I in preparation of anti-Mycobacterium tuberculosis drugs or/and blood lipid lowering drugs.
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Paragraph 0121-0126
(2019/11/29)
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- Cyclopeptides and polyketides from coral-associated fungus, Aspergillus versicolor LCJ-5-4
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Three new cyclopentapeptides, versicoloritides A-C (1-3), a new orcinol tetramer, tetraorcinol A (4), and two new lactones, versicolactones A and B (5 and 6) together with three known metabolites, diorcinol, glyantrypine, and cordyol C were isolated from the fermentation broth of the coral-associated fungus Aspergillus versicolor LCJ-5-4. Their structures were elucidated by spectroscopic and chemical methods. The new compounds 1-4 were evaluated for their radical-scavenging activity and antimicrobial activity against Staphylococcus aureus, Escherichia coli, Enterobacter aerogenes, Bacillus subtilis, Pseudomonas aeruginosa, and Candida albicans and cytotoxicity against P388 and Hela cell lines. Compound 4 showed weak radical-scavenging activity against the DPPH radical with an IC50 value of 67 μM.
- Zhuang, Yibin,Teng, Xiancun,Wang, Yi,Liu, Peipei,Wang, Hui,Li, Jing,Li, Guoqiang,Zhu, Weiming
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experimental part
p. 7085 - 7089
(2011/10/09)
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- Hydration of amino acids from ultrasonic measurements
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In this paper the results of compressibility of aqueous solutions of amino acids in water and in aqueous HCl and NaOH solutions at 25 °C are presented. The effect of the charged protonated amino groups and deprotonated carboxylic groups on the hydration number was tested. The idea of additivity of the hydration number with the constituents of the solute molecule was successfully applied and discussed.
- Burakowski, Andrzej,Gliński, Jacek
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experimental part
p. 12157 - 12161
(2011/01/11)
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- Stereospecific Synthesis of α-Deuteriated α-Amino Acids: Regiospecific Deuteriation of Chiral 3-Isopropyl-2,5-dimethoxy-3,6-dihydropyrazines
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Base-catalysed deuteriation of (3R)- or (3S)-3-isopropyl-2,5-dimethoxy-3,6-dihydropyrazines in refluxing CH3O2H-2H2O gives the -isotopomer in excellent yields without disturbing the stereogenic centre at C-3.These compounds provide convenient and efficient access to a range of (R)- and (S)-α-deuteriated α-amino acids, including serine, aspartic acid, allylglycine and phenylalanine, via alkylation of the butyllithium generated C-6 anion.
- Rose, Janet E.,Leeson, Paul D.,Gani, David
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p. 157 - 166
(2007/10/02)
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- 2-Azido-3-benzyloxy-propionic acid-benzyl ester, process for its production and its use
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The subject matter of the invention is the new 2-azido-3-benzyloxy-propionic acid benzyl ester which is a valuable intermediate product for the production of D,L-serine or derivatives of D,L-serine. The new compound is produced by reacting 2-chloroacrylonitrile with twice the molar amount of benzyl alcohol to form 3-benzyloxy-2-chloropropionic acid imino benzyl ester, saponifying this with acid to form 3-benzyloxy-2-chloropropionic acid benzyl ester, and finally exchanging the chlorine atom by means of an alkali metal azide in the presence of a phase transfer catalyst for an azido group.
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