- Crystallization Does It All: An Alternative Strategy for Stereoselective Aza-Henry Reaction
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An efficient and experimentally straightforward method for the stereoselective synthesis of a variety of β-nitro-α-amino carboxylic acids via aza-Henry (nitro-Mannich) reaction of aldimines is disclosed, yielding either anti- or a rarely reported syn-configuration. The reaction operates directly on free glyoxylic acid and generates imine species in situ. Crystallization-controlled diastereoselectivity enables isolation of the target compounds in high enantio- and diastereomeric purities by a simple filtration.
- Mar?eková, Michaela,Ger?a, Peter,?oral, Michal,Moncol, Ján,Berke?, Du?an,Kolarovi?, Andrej,Jakubec, Pavol
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supporting information
p. 4580 - 4584
(2019/06/17)
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- Tn Antigen Mimics by Ring-Opening of Chiral Cyclic Sulfamidates with Carbohydrate C1- S- and C1- O-Nucleophiles
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Starting from commercially available (S)-isoserine and effectively accessible (S)-α-methylserine, enantiopure cyclic sulfamidates have been prepared as chiral building blocks for the synthesis of various S- and O-glycosylated amino acid derivatives, inclu
- Tovillas, Pablo,García, Iván,Oroz, Paula,Mazo, Nuria,Avenoza, Alberto,Corzana, Francisco,Jiménez-Osés, Gonzalo,Busto, Jesús H.,Peregrina, Jesús M.
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p. 4973 - 4980
(2018/05/17)
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- Preparation method and application of D-dencichine
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The invention discloses a preparation method and application of D-dencichine. The preparation method comprises the following steps: carrying out Fmoc protection on the amino group of D-asparagine so as to obtain a first intermediate; subjecting the first intermediate to Hoffman degradation reaction so as to obtain a second intermediate; subjecting the second intermediate to removal of Fmoc protection under the action of organic base so as to obtain a third intermediate; and subjecting the third intermediate and monomethyl oxalate to condensation reaction under a highly basic condition so as to obtain D-dencichine. D-dencichine is prepared by using the high-efficiency safe preparation method; the preparation method is simple and has high yield; the compound D-dencichine prepared by using the method has good treatment effect on thrombocytopenia and the effect is better than the effect of a clinical medicine interleukin-11, so D-dencichine can be used as a candidate medicine for treating thrombocytopenia.
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Paragraph 0081; 0082
(2016/10/17)
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- Bacterial preparation of enantiopure unactivated aziridine-2-carboxamides and their transformation into enantiopure nonnatural amino acids and vic-diamines
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Enantiopure (1R,2S)-1-benzyl- and 1-arylaziridine-2-carboxamides were obtained by kinetic resolution of their racemates by Rhodococcus rhodochrous IFO 15564 catalyzed hydrolysis. Several regio- and enantioselective nucleophilic ring openings of (1R,2S)-1-benzylaziridine-2-carboxamide or its LAH-reduced product led to a series of enantiopure products, such as O-methyl-L-serine and some vicinal diamines.
- Moran-Ramallal, Roberto,Liz, Ramon,Gotor, Vicente
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p. 521 - 524
(2007/10/03)
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- A new and facile route for the synthesis of chiral 1,2-diamines and 2,3-diamino acids
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The synthesis of chiral diamines and diamino acids has been achieved from the corresponding N-arylsulfonyl aziridines through reaction with a chiral isocyanate and subsequent hydrolysis of 2-imidazolidinones. The method appears to be general and of wide applicability.
- Nadir, Upender K.,Krishna, R. Vijaya,Singh, Anamika
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p. 479 - 482
(2007/10/03)
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- An improved stereoselective synthesis of L-alanosine
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An improved, stereoselective synthesis of the natural, non-proteogenic amino acid L-alanosine has been developed, starting from the readily available and cheap substrate L-serine, in six steps and 49% overall yield. The process is very efficient, is suitable for large-scale production, and affords L-alanosine with properties comparable with those of the natural substance. In addition, the structural assignment concerning some previously reported synthetic alkylated derivatives of the natural amino acid has been definitively confirmed. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
- Strazzolini, Paolo,Dall'Arche, Maria Grazia,Zossi, Maura,Pavsler, Andrea
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p. 4710 - 4716
(2007/10/03)
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- Flexible and convergent total synthesis of cyclotheonamide B
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A convergent approach using two key intermediates, segment A [a L-proline-L-α-hydroxy-β-homoarginine-D-phenylalamine (Pro-hArg-D-Phe) tripeptide] and segment B [a vinylogous L-tyrosine-L-2,3-diaminopropanoic acid (vTyr-Dpr) dipeptide], was developed for the synthesis of cyclotheonamide B. The starting compound for the preparation of the hArg moiety 7, the predominant part of segment A, was N(α)-(benzyloxycarbonyl)-N(ω),N(ω)'-bis(tert-butyloxycarbonyl)-l-ar ginine methyl ester (15), which was converted into the aldehyde 16 and subsequently homologated using [tris(methylthio)methyl]lithium as a carboxylic acid anion equivalent. Coupling with properly protected Pro and D-Phe derivatives gave smoothly the desired Pro-hArg-D-Phe tripeptide derivative 24. The key feature of segment B, i.e., the L-tyrosine-derived α,β-unsaturated γ-amino acid 4, was prepared by a Wadsworth-Emmons olefination of the aldehyde 29 derived from N-(tert-butyloxycarbonyl), O-tert-butyl-L-tyrosine methyl ester (28). Selective N-(tert-butyloxycarbonyl) removal in the presence of the aryl tert-butyl ether present in the fully protected segment B, i.e., 32, was achieved by treatment with trimethylsilyl triflate/2,6-lutidine to give vTyr-Dpr dipeptide derivative 34 in quantitative yield. Coupling of the key intermediates 24 and 34 using 2-(1H-benzotriazol-1-yl)-1,1,3,3-tetramethyluronium tetrafluoroborate (TBTU) afforded the protected linear pentapeptide 35 in high yield. Treatment of 35 with Pd(PPh3)4/morpholine resulted in simultaneous removal of the C-terminal allyl group and the N-terminal allyloxycarbonyl group to yield 36. Ring closure was effected under dilution conditions by treatment with TBTU/1-hydroxybenzotriazole/4-(dimethylamino)pyridine and gave the protected cyclopentapeptide 37 in 61% yield. Oxidation of the hydroxyl group with Dess-Martin periodinane (24 h, 40°C) in the presence of tert-butyl alcohol gave 38, which was then subjected to O,N-deprotection with trifluoroacetic acid/thioanisole. Subsequent HPLC purification afforded cyclotheonamide B in an overall yield of 1.8% in 17 steps.
- Bastiaans, Harold M.M.,Van der Baan, Juul L.,Ottenheijm, Harry C.J.
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p. 3880 - 3889
(2007/10/03)
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- Stereochemistry of Nucleophilic Ring-Opening Reactions of Optically Active N-Acetyl-2-Methoxycarbonylaziridine.
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The SN2-like mechanism of the nucleophilic attack of sodium azide on (S)-(-)-N-acetyl-2-methoxycarbonylaziridine was verified through the chemical correlation of the ring-opening products with (S)-(+)- or (R)-(-)-2,3-diaminopropanoic acid monohydrochloride.
- Davoli, Paolo,Forni, Arrigo,Moretti, Irene,Prati, Fabio
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p. 2011 - 2016
(2007/10/03)
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- Regioselectivity of Ring-Opening Reactions of Optically Active N-Acetyl-2-Methoxycarbonylaziridine
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(S)-(-)-N-acetyl-2-methoxycarbonylaziridine 1 undergoes easy ring-opening by Broensted acids or nucleophiles in the presence of a Lewis acid catalyst.The regioselectivity is not always exclusive, affording optically active α- and β-aminoacids.
- Bucciarelli, Maria,Forni, Arrigo,Moretti, Irene,Prati, Fabio,Torre, Giovanni
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p. 2073 - 2080
(2007/10/03)
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- A new approach to the synthesis of enantiomerically pure 2,3-diaminoacids through chiral imidazolidin-2-ones
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The synthesis of enantiomerically pure 5-iodomethylimidazolidin-2-ones (3a-c) and (4a-c) is reported, by means of iodocyclisation of allylic tosylureas (2a-c). Starting from pure (3a) and (4a), a synthesis of both (R)- and (S)-2,3-diaminopropanoic acid is
- Cardillo, Giuliana,Orena, Mario,Penna, Maurizio,Sandri, Sergio,Tomasini, Claudia
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p. 2263 - 2272
(2007/10/02)
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- Synthesis of Pyrimidoblamic Acid and Epipyrimidoblamic Acid
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The N-protected pyrimidine moieties of bleomycin (pyrimidoblamic acid, 1) and epibleomycin are reported.In addition to a complete description of a synthetic route outlined earlier (Arai, H.; Hagmann, W.K.; Suguna, H.; Hecht, S.M.J.Am.Chem.Soc. 1980, 102,
- Aoyagi, Yoshiaki,Chorghade, Mukund S.,Padmapriya, Abeysinghe A.,Suguna, Hosbett,Hecht, Sidney M.
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p. 6291 - 6298
(2007/10/02)
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