82078-97-5Relevant academic research and scientific papers
A Practical Method for Optical Resolution of Racemic Alcohols or Esters via Lipase-Catalyzed Transformation and Sulfation
Yamano, Toru,Kikumoto, Fumio,Yamamoto, Shozo,Miwa, Katsuhiko,Kawada, Mitsuru,Ito, Tatsuya,Ikemoto, Tomomi,Tomimatsu, Kiminori,Mizuno, Yukio
, p. 448 - 449 (2000)
Optically active esters were conveniently obtained from the corrasponding racemic alcohols or esters by lipase-catalyzed transformation, followed by sulfation. Sulfation by sulfurtrioxide pyridine complex enabled facile isolation of optically active esters by extraction instead of laborious column chromatography. The method would be especially adventageous on a large scale.
Batch and Continuous-Flow One-Pot Processes using Amine Diazotization to Produce Silylated Diazo Reagents
Audubert, Clément,Gamboa Marin, Oscar Javier,Lebel, Hélène
supporting information, p. 6294 - 6297 (2017/05/19)
A novel synthesis of trimethylsilyldiazomethane (TMSCHN2) by diazotization of trimethylsilylmethylamine (TMSCH2NH2) is reported using batch and continuous flow synthesis. The latter affords a daily production of 275 g (2.4 mol) of TMSCHN2. Other silylated methylamines were also successfully reacted under the developed reaction conditions to furnish various silicon-bearing diazomethane reagents. The applicability of the process is highlighted by disclosure of batch and continuous flow one-pot esterification and 1,3-dipolar cycloaddition processes. Furthermore, the high-yielding esterification of carboxylic acids with silylated and substituted methylamines in continuous flow is disclosed. Finally, work-up and purification procedures are reported for the preparation of a 2-MeTHF solution of TMSCHN2, which can be used in rhodium-catalyzed methylenation and homologation reactions.
Chemoenzymatic Preparation of Enantiomerically Enriched (R)-(–)-Mandelic Acid Derivatives: Application in the Synthesis of the Active Agent Pemoline
Potera?a, Marcin,Dranka, Maciej,Borowiecki, Pawe?
, p. 2290 - 2304 (2017/05/01)
The enantioselective resolution of several racemic derivatives of mandelic acid methyl ester catalyzed by lipases from Pseudomonas fluorescens (Amano AK) or Burkholderia cepacia (Amano PS-C II and Amano PS-IM) has been achieved. A gram-scale lipase-mediated kinetic resolution approach has been developed that allows the facile synthesis of the corresponding methyl (R)-(–)-mandelates with excellent enantiomeric excesses (up to >99 % ee) and reaction enantioselectivity (E values up to >200). The dopaminergic agent pemoline, used in the treatment of attention-deficit hyperactivity disorder (ADHD) and narcolepsy, was synthesized with 98 % ee in a straightforward route by condensing the prepared methyl (R)-(–)-mandelate with guanidine hydrochloride under basic conditions. The desired (R)-(+)-pemoline in optically pure form (>99 % ee) was obtained after two recrystallizations from ethanol. However, it was confirmed by chiral HPLC that optically active pemoline undergoes racemization in methanol solution.
The assignment of the configuration for α-hydroxy acid esters using a CEC strategy
Peng, Ruixue,Lin, Lili,Zhang, Yuheng,Wu, Wangbin,Lu, Yan,Liu, Xiaohua,Feng, Xiaoming
, p. 5258 - 5262 (2016/07/06)
A simple and efficient 1H NMR method for determining the absolute configuration of chiral α-hydroxy acid esters using a competing enantioselective conversion (CEC) strategy was developed. The α-hydroxy acid esters were acylated in the presence
Synthesis of arylglycine and mandelic acid derivatives through carboxylations of α-amido and α-acetoxy stannanes with carbon dioxide
Mita, Tsuyoshi,Sugawara, Masumi,Hasegawa, Hiroyuki,Sato, Yoshihiro
, p. 2159 - 2168 (2012/06/01)
Incorporation reactions of carbon dioxide (CO2) with N-Boc-α-amido and α-acetoxy stannanes were developed using CsF as a mild tin activator. Monoprotected α-amido stannanes could be used, and the corresponding arylglycine derivatives were obtained in moderate-to-high yields under 1 MPa (10 atm) of CO2 pressure. α-Acetoxy stannanes also underwent carboxylation to afford mandelic acid derivatives in excellent yields under ambient CO2 pressure. Both transformations enabled the synthesis of α-tertiary and α-quaternary carboxylic acid derivatives. In addition, the chirality of (S)-N-tert-butylsulfonyl-α- amido stannanes was transferred with up to 90% inversion of configuration at 100 °C.
Kinetic resolution of α-acetoxy N-acyl oxazolidinethiones by a chiral O-nucleophilic acyl transfer catalyst
Nolle, Gregory T.,Sammakia, Tarek,Steel, Peter J.
, p. 13502 - 13503 (2007/10/03)
The kinetic resolution of α-acetoxy N-acyl oxazolidinethiones using the chiral, nonracemic O-nucleophilic acyl transfer catalyst 8 is described. The reaction proceeds on a variety of substrates in excellent yields, with s-factors ranging from 17 to 31. Copyright
Highly powerful and practical acylation of alcohols with acid anhydride catalyzed by Bi(OTf)3
Orita,Tanahashi,Kakuda,Otera
, p. 8926 - 8934 (2007/10/03)
Bi(OTf)3-catalyzed acylation of alcohols with acid anhydride was evaluated in comparison with other acylation methods. The Bi(OTf)3/acid anhydride protocol was so powerful that sterically demanding or tertiary alcohols could be acylated smoothly. Less reactive acylation reagents such as benzoic and pivalic anhydride are also activated by this catalysis. In these cases, a new technology was developed in order to overcome difficulty in separation of the acylated product from the remaining acylating reagent: methanolysis of the unreacted anhydride into easily separable methyl ester realized quite easy separation of the desired acylation product. The Bi(OTf)3/acid anhydride protocol was applicable to a wide spectrum of alcohols bearing various functionalities. Acid-labile THP- or TBS-protected alcohol, furfuryl alcohol, and geraniol could be acylated as well as base-labile alcohols. Even acylation of functionalized tertiary alcohols was effected at room temperature.
Dynamic kinetic resolution of α-hydroxy acid Esters
Huerta, Fernando F.,Laxmi, Y.R. Santosh,Baeckvall, Jan-E.
, p. 1037 - 1040 (2007/10/03)
Enzymatic resolution in combination with ruthenium-catalyzed racemization of the substrate led to dynamic kinetic resolution of α-hydroxy esters in good yields and excellent ee's. Studies of different parameters showed that the best results were obtained
Highly efficient chemo- and enantioselective enzymatic resolution of (+/-)-methyl O-acetylmandelates
Desai, Shrivallabh B.,Ganesh, Krishna N.,Argabe, Narshinha P.
, p. 918 - 920 (2007/10/03)
Chemo- and enantioselective enzymatic hydrolysis of (+/-)-methyl O-acetylmandelates using AmanoPS has been described with very high yields and optical purity of the products.
Enantioselectivity of Pseudomonas cepacia lipase for the acetylation of 2-hydroxy carboxylic acid esters+
Sundholm, Oskari,Kanerva, Liisa T.
, p. 625 - 640 (2007/10/03)
Structurally different ethyl or methyl 2-hydroxy carboxylates were resolved by Pseudomonas cepacia lipase-catalysed acetylations with vinyl acetate in diethylether. One type of the alcoholic substrates (2-hydroxy-2-arylacetates and 2-hydroxy-3-arylpropinates) contained a HO-group at the stereocentre. These compounds were resolved with high enantioselectivity (ee 91 → 99) at ca. 50% conversion. The other alcoholic substrates ((threo-2-hydroxy-3-methylbutyrate and threo- or erythro-2-hydroxy-3-aryl-3-arylthio(or aryloxy)propionates) with two stereocentres generally resulted in enantiopure products and the reactions stopped at 50 % conversion.
