- Designing enzymatic resolution of amines
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A new strategy, utilizing IR and mass spectrometry, has been developed to design appropriate reagents and reaction conditions for enantioselective enzymatic protection of amines with readily removable protecting groups.
- Takayama, Shuichi,Lee, Shelly T.,Hung, Shang-Cheng,Wong, Chi-Huey
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Read Online
- Synthesis of Aminomethylene- gem-bisphosphonates Containing an Aziridine Motif: Studies of the Reaction Scope and Insight into the Mechanism
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A broad range of N-carbamoylaziridines were obtained and then treated by the diethyl phosphonate anion to afford α-methylene-gem-bisphosphonate aziridines. Study of the reaction's scope and additional experiments indicates that the transformation proceeds via a new mechanism involving the chelation of lithium ion. This last step is crucial for the reaction to occur and disfavors the aziridine ring-opening. A phosphonate-phosphate rearrangement from a α-hydroxybisphosphonate aziridine intermediate is also proposed for the first time. This reaction provides a simple and convenient method for the synthesis of a highly functionalized phosphonylated aziridine motif.
- Cheviet, Thomas,Peyrottes, Suzanne
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p. 3107 - 3119
(2021/02/05)
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- A method for preparing weinaweina kalland hydrochloride (by machine translation)
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The invention discloses a method for preparing weinaweina kalland hydrochloride. The method to selectively amino protection, nucleophilic addition, nucleophilic substitution, deprotected, cyclized, reduction, into a salt by the reaction of the compound Wina carland hydrochloride. And after nuclear magnetic analysis test technology confirm its structure. It adopts the cheap and easily obtained starting materials to prepare, preparation method has advantages of simple operation, mild condition, easy industrialized production and the like, and avoids the use of heavy metal, is beneficial to the development of the oral. (by machine translation)
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Paragraph 0048; 0051-0052
(2017/11/27)
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- Purification method of vernakalant hydrochloride
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The invention discloses a purification method of vernakalant hydrochloride. The method comprises the steps of preparation of a vernakalant hydrochloride crude product and purification through the process of alkalinization, nonpolar solvent extraction, acidification and mixed solvent pulping, and thus a qualified product is obtained. The preparation method is simple in operation, mild in condition and easy for industrialized production, and the purity of the product reaches 99.9 percent, and the total impurity and single impurity are both less than 0.1 percent, so that the quality requirements for preparing medicine can be reached, and at the same time, the usage of heavy metal is avoided, and the development of injection forms is facilitated.
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Paragraph 0048-0049
(2017/01/12)
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- Enhanced rate and selectivity by carboxylate salt as a basic cocatalyst in chiral N-heterocyclic carbene-catalyzed asymmetric acylation of secondary alcohols
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The rate and enantioselectivity of chiral NHC-catalyzed asymmetric acylation of alcohols with an adjacent H-bond donor functionality are remarkably enhanced in the presence of a carboxylate cocatalyst. The degree of the enhancement is correlated with the basicity of the carboxylate. With a cocatalyst and a newly developed electron-deficient chiral NHC, kinetic resolution and desymmetrization of cyclic diols and amino alcohols were achieved with extremely high selectivity (up to s = 218 and 99% ee, respectively) at a low catalyst loading (0.5 mol %). This asymmetric acylation is characterized by a unique preference for alcohols over amines, which are not converted into amides under the reaction conditions.
- Kuwano, Satoru,Harada, Shingo,Kang, Bubwoong,Oriez, Raphael,Yamaoka, Yousuke,Takasu, Kiyosei,Yamada, Ken-Ichi
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supporting information
p. 11485 - 11488
(2013/09/02)
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- New procedure for the preparation of (1 R,2 R)-2-[(R)-3-(benzyloxy)pyr- rolidin-1-yl]cyclohexanol
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A novel route to an intermediate of vernakalant, (1R,2R)-2-[(R)-3- (benzyloxy)pyrrolidin-1-yl]cyclohexanol from ethyl (R)-4-chloro-3- hydroxybutanoate is described. It was found that the key intermediate (R)-4-(benzyloxy)-1-[(1R,2R)-2-(tert-butyldimethylsiloxy)cyclohexyl] pyrrolidin-2-one could be isolated with high dia-stereomeric excess (up to 99% de) from its isomer by column chromatography alone, without further chemical resolution. Georg Thieme Verlag Stuttgart. New York.
- Ye, Haiwei,Yu, Chuanming,Zhong, Weihui
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experimental part
p. 51 - 56
(2012/04/10)
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- Alkyl 4-chlorobenzoyloxycarbamates as highly effective nitrogen source reagents for the base-free, intermolecular aminohydroxylation reaction
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Ethyl-(7), benzyl-(8), tert-butyl-(9), and fluorenylmethyl-4- chlorobenzoyloxycarbamates (10) have been prepared as storable and easy-to-prepare nitrogen sources for use in the intermolecular Sharpless aminohydroxylation reaction and its asymmetric variant. These reagents were found to be effective under base-free reaction conditions. The scope and limitations of these methods have been explored using a variety of alkenes, among which, trans-cinnamates, in particular, proved to be good substrates.
- Harris, Lawrence,Mee, Simon P. H.,Furneaux, Richard H.,Gainsford, Graeme J.,Luxenburger, Andreas
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experimental part
p. 358 - 372
(2011/04/17)
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- IMPROVED AMINOHYDROXYLATION OF ALKENES
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The invention relates to a process for the aminohydroxylation of alkenes using N-oxycarbamate reagents, e.g. N-acyloxycarbamate, N-alkyloxycarbonyloxycarbamate and N-aralkoxycarbonyloxycarbamate reagents. The invention particularly relates to an intermolecular aminohydroxylation reaction that can be carried out in the absence of added base. The invention also relates to novel N-oxycarbamate reagents that are stable crystalline materials. The process of the invention is useful in the synthesis of compounds having a vicinal amino alcohol moiety, such as biologically active compounds.
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Page/Page column 52
(2012/01/06)
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- A General Route to the Synthesis of N-Protected 1-Substituted and 1,2-Disubstituted Taurines
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N-Benzyloxycarbonyl protected α-substituted and αβ- disubstituted taurines were synthesized from olefins and epoxides via N-benzyloxycarbonylamino alcohol thioacetates as key intermediates. They are important sulfur analogues of naturally occurring amino acids and building blocks for the synthesis of α-substituted and α,β- disubstituted β-sulfonopeptides.
- Xu, Jiaxi,Xu, Shu
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p. 276 - 282
(2007/10/03)
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- Enzymatic resolution of (±)-cis-2-aminocyclopentanol and (±)-cis-2- aminocyclohexanol
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(±)-cis-N-Benzyloxycarbonyl-2-aminocyclopentanol was efficiently resolved by O-acylation with Pseudomonas cepacia lipase, as was (±)-cis-N- benzyloxycarbonyl-2-aminocyclohexanol when Candida antarctica lipase was used.
- Luna, Amparo,Astorga, Covadonga,Fueloep, Ferenc,Gotor, Vicente
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p. 4483 - 4487
(2007/10/03)
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- Enzymatic resolution of (±)-trans-2-aminocyclohexanol and (±) trans-2-aminocyclopentanol
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Candida antarctica lipase (CAL) catalyzes the resolution of (±)-trans-2-aminocyclohexanol by alkoxycarbonylation or acylation reactions. Besides, N-benzyloxycarbonyl derivatives of (±)-trans-2-aminocyclohexanol and (±)-trans-2-aminocyclopentanol are efficiently resolved through O-acylation by Pseudomonas cepacia lipase (PSL).
- Maestro, Alicia,Astorga, Covadonga,Gotor, Vicente
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p. 3153 - 3159
(2007/10/03)
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- Preparation of 2-oxazolidinones by intramolecular nucleophilic substitution
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Treatment of N-alkoxycarbonyl, N-benzyl protected β-amino alcohols with triphenylphosphine and hexachloroethane in 1,2-dichloroethane induces cyclization to 2-oxazolidinones, which are formed by intramolecular attack with inversion of configuration at the secondary alcohol. In contrast, mono N-substituted alkyl carbamates undergo chlorination under the same conditions.
- Van Delft, Floris L.,Timmers, Cornelis M.,Van Der Marel, Gijs A.,Van Boom, Jacques H.
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p. 450 - 454
(2007/10/03)
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- A General Method for the Separation of Enantiomeric trans-2-Substituted Cyclohexanols
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An number of different racemic, trans-2-substituted cyclohexanols has been prepared in high optical purity by optical resolution of the respective 2'-substituted cyclohexyl butanoates with the aid of commercially available lipases.
- Hoenig, Helmut,Seufer-Wasserthal, Peter
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p. 1137 - 1140
(2007/10/02)
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