- D-tyrosine a method for asymmetric synthesis of
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A provided asymmetric syntheses method for D-tyrosine comprises the following steps: performing a condensation reaction on p-hydroxybenzaldehyde and acetylglycine, then performing hydrolysis or alcoholysis to obtain a dehyddroamino acid or ester; and then utilizing rhodium to perform catalytic asymmetric hydrogenation, and performing hydrolysis to obtain a key intermediate D-tyrosine. According to the method, the whole process has no complex separation steps, the preparation technology is simple, a chromatography column is not needed, the reaction steps can be further reduced by utilizing rhodium catalysis asymmetric hydrogenation technology, the production cost is reduced, and the method is extremely suitable for industrialized batch production.
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Paragraph 0039-0048
(2019/02/02)
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- Concise synthesis of (-)-anisomycin
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The antibiotic (-)-anisomycin was synthesized starting from d-tyrosine using Sharpless asymmetric epoxidation as a key reaction followed by formation and hydrolysis of oxazoline set up all chiral center.
- Li, Ji,Feng, Yan Hua,Li, Xin Bai,Han, Wei,Liu, Huan Qiu,Shao, Guo Guang
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scheme or table
p. 647 - 649
(2012/08/13)
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- Two-colour screening in combinatorial chemistry: prospecting for enantioselectivity in a library of steroid-based receptors
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The screening of resin-bound combinatorial libraries with pairs of dye-tagged substrates is a powerful strategy for discovering selective receptors. However, implementation has been hampered by a lack of complementary but chemically similar dyes. We now s
- del Amo, Vicente,McGlone, Adam P.,Soriano, José M.,Davis, Anthony P.
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scheme or table
p. 6370 - 6381
(2009/12/04)
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- A novel tea-bag methodology for enzymatic resolutions of α-amino acid derivatives in reverse micellar media
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A novel tea bag methodology for resolution of methyl esters of N-acetyl- α-amino acids in reverse micellar medium of bis(2-ethylhexyl) sulfosuccinate sodium salt (AOT) in isooctane-chloroform using immobilized enzymes or microbial cells is presented. The methodology effectively solves the problems of substrate solubility, product separation and surfactant recycling and provides products in high yields (80 to 90%) and excellent optical purities (% ee 97 to >99%).
- Bhalerao,Rao,Fadnavis
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p. 2109 - 2118
(2007/10/02)
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- Synthesis and application of (3R,4R)-3,4-bis(diphenylphosphino)tetrahydrofuran as ligand for asymmetric hydrogenation of acrylic acids
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A new, chiral bisphosphine, (3R,4R)-3,4-bis(diphenylphosphino)tetrahydrofuran (4), is synthesized in three steps from (R,R)-tartaric acid esters. With rhodium(I) complexes of 4 enantiomeric excesses of 54 to 97% are obtained on catalytic hydrogenation of 2-(acetylamino)acrylic acid, 2-(acetylamino)cinnamic acids and itaconic acid. The applied substrate/catalyst ratios were between 250:1 and 11,000:1.
- Terfort
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p. 951 - 953
(2007/10/02)
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- Efficient Asymmetric Hydrogenations of (Z)-2-Acetamidoacrylic Acid Derivatives with the Cationic Rhodium Complex of (2S,4S)-MOD-BPPM
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The preparation of (2S,4S)-MOD-BPPM ((2S,4S)-N-(t-butoxycarbonyl)-4-phosphino>-2-phosphino>methyl>pyrrolidine) and its application to highly effective asymmetric hydrogenations of (Z)-2-acetamidoacrylic acid derivatives are described.
- Takahashi, Hisashi,Achiwa, Kazuo
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p. 305 - 308
(2007/10/02)
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- Asymmetric Synthesis. Asymmetric Catalytic Hydrogenation Using Chiral Chelating Six-Membered Ring Diphosphines
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Rhodium(I) catalysts formed by the two chiral chelating six-membered ring diphosphines, 2,4-bis(diphenylphosphino)pentane (skewphos) and 1,3-bis(diphenylphosphino)butane (chairphos), are efficient catalysts for the hydrogenation of amino acid precursors.The two chiral phosphines differ in that skewphos probably adopts a chiral conformation whereas chairphos probably adopts an achiral conformation.This comparison evidences the importance of ring conformations in determining optical yields.The mechanism of asymmetric hydrogenation is discussed, and a number of particular and general conclusions are drawn which may prove useful in predicting optical yields from asymmetric synthesis.
- MacNeil, Patricia A.,Roberts, Nicholas K.,Bosnich, B.
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p. 2273 - 2280
(2007/10/02)
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- Transition-Metal-Catalyzed Asymmetric Organic Synthesis via Polymer-Attached Optically Active Phosphine Ligands. 5. Preparation of Amino Acids in High Optical Yield via Catalytic Hydrogenation
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Two new optically active phosphinopyrrolidine monomers were prepared by the reaction of (2S,4S)-4-(diphenylphosphino)-2-pyrrolidine and (2R,4R)-4-(diphenylphosphino)-2-pyrrolidine with acryloyl chloride to give N-acryloyl-(2S,4S)-4-(diphenylphosphino)-2-pyrrolidine (1) and N-acryloyl-(2R,4R)-4-(diphenylphosphino)-2-pyrrolidine (2).Copolymerization of 1 and 2 with hydrophilic comonomers and a divinyl monomer provided cross-linked insoluble polymers containing 3-5percentof 1 or 2 that would swell in polar solvents.Exchange of rhodium (I) onto the polymer gave catalysts which were active for the asymmetric hydrogenation of N-acyl α-amino acids in high optical yields, the phosphine derived from the enantiomer of the naturally occurring 4-hydroxyproline giving (S)-amino acids.The catalysts could be reused with no loss in selectivity by simple filtration.
- Baker, Gregory L.,Fritschel, Scott J.,Stille, John R.,Stille, John K.
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p. 2954 - 2960
(2007/10/02)
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