- Amino Acid Anhydride Hydrochlorides as Acylating Agents in Friedel-Crafts Reaction: A Practical Synthesis of L-Homophenylalanine
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The use of amino acid hydrochlorides as acylating agents in Friedel-Crafts reaction is presented for the first time. A practical and convenient route to L-homophenylalanine from L-aspartic acid in 3 steps in 80 percent overall yield with >99 percent ee is thus achieved.
- Lin, Wenqing,He, Ze,Zhang, Haile,Zhang, Xiaomei,Mi, Aiqiao,Jiang, Yaozhong
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- Preparation method of N -fluorenylmethoxycarbonyl - L -aspartic -4 -tert-butyl ester
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The invention relates to the technical field of organic synthesis, in particular to a preparation method of a fluorenylmethoxycarbonyl - aspartic -4 - tert-butyl ester, which comprises the following specific steps: L - aspartic acid is used as a starting raw material, L - aspartic acid internal anhydride hydrochloride is obtained through dehydration treatment of phosphorus trichloride. L- Aspartic acid ester hydrochloride and ethanol were subjected to alcoholysis to obtain L -aspartate hydrochloride. The transesterification reaction L-aspartate and tert-butyl ester gives L -butyl-1 -ethyl-4 -butyl acrylate. Further hydrolysis L-butyl-1 - ethyl ester -4 - gives L -butyl-4 -tert-butyl ester. The L-aspartate -4 - tert-butyl ester is reacted with the fluorenylmethoxycarbonyl reagent to obtain the target product fluorenylmethoxycarbonyl - aspartic -4 -tert-butyl ester. The preparation method of the fluorenylmethoxycarbonyl - aspartic -4 - tert-butyl ester provided by the invention is safe and environment-friendly in production process and suitable for industrial large-scale production.
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Paragraph 0013; 0027-0029; 0036-0038
(2021/08/25)
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- A polypeptide material aspartic acid tert-butyl β - α - methyl ester hydrochloride preparation method
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The invention discloses a polypeptide material aspartic acid tert-butyl β - α - methyl ester hydrochloride of the preparation method, is mainly composed of complex technology, cycle is long, the yield is low, the cost is high, the risk is high, does not meet the technical problems of production and the like. Preparation method of this invention comprises the following steps: 1st step, the aspartic acid suspended in dry tetrahydrofuran, in phosphorus oxychloride under the action of the aspartic acid in the preparation into the anhydride hydrochloride; 2nd step, aspartic acid anhydride hydrochloride suspended in methanol reaction to obtain the aspartic acid α - methyl ester hydrochloride, triethylamine for adjusting pH value so that the aspartic acid methyl α - separated out; 3rd step, aspartic acid methyl α - suspended in methylene chloride, access isobutene, concentrated sulfuric, sealed reaction to obtain the oil of aspartic acid tert-butyl methyl α - β -; 4th step, the oil of aspartic acid tert-butyl methyl α - β - dissolved in ethyl ether, dropping ethyl ether - hydrochloric acid gas, the final product is obtained α - β - tert-butyl aspartic acid methyl ester hydrochloride.
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Paragraph 0014; 0019; 0023
(2019/01/08)
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- Synthesis of novel chiral oxazoline ligands and application in the highly enantioselective diethylzinc addition to N-diphenylphosphinoylimines
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Two sets of novel chiral oxazoline ligands were designed and conveniently prepared from readily available l-aspartic acid and evaluated in enantioselective diethylzinc addition to N-diphenylphosphinoyl imines. In the presence of stoichiometric amounts of these ligands, high enantioselectivities (up to 95% ee) and yields (up to 85%) were achieved for several aromatic imines in toluene at room temperature. Furthermore, the effect of the structure of the ligand on the reaction was studied.
- Yan, Gexin,Wu, Yong,Lin, Wenqing,Zhang, Xiaomei
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p. 2643 - 2648
(2008/04/05)
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- Process for isolation of aspartyl dipeptide esters
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The isolation of certain dipeptide esters, known to be potent sweetening agents, is achieved by selectively extracting, with a suitable alkanol in a heterogeneous system, an aqueous solution containing the dipeptide ester together with a variety of impurities.
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