- Amino Acids. 7. A Novel Synthetic Route to L-Proline
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Reaction of L-5-oxoproline esters L-2 with phosgene at 0 deg C gives L-5,5-dichloro-1-(chlorocarbonyl)proline esters L-6, which readily lose hydrogen chloride to form L-5-chloro-1-(chlorocarbonyl)-4,5-dehydroproline esters L-7.Catalytic hydrogenation (Pd/C, 180 bar) of L-7 yields L-1-(chlorocarbonyl)proline esters L-15 and thence, upon hydrolysis, L-proline (L-17).A 'one-pot reaction' for the whole sequence is described, starting from easily accessible L-5-oxoproline esters and yielding L-proline in 78percent overall yield and 99.7percent optical purity.
- Drauz, Karlheinz,Kleemann, Axel,Martens, Juergen,Scherberich, Paul,Effenberger, Franz
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- Oxidation of L-Proline Methyl Ester Derivatives with the Iodosylbenzene/Trimethylsilylazide Reagent Combination
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Oxidation of a series of L-Proline derivatives with the (PhIO)n/TMSN3 reagent combination is reported.Subsequent utilization of the 5-azido N-acyl functionality as a N-acyl iminium ion precursor is described.
- Magnus, Philip,Hulme, Christopher
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- A METHOD FOR FLUORINATED RING-OPENING OF A SUBSTRATE
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Disclosed herein, inter alia, are methods useful for making a fluoroalkyl amine and methods useful for making an α-oxygenated cyclic amine.
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Paragraph 0260; 0290; 0304
(2019/12/25)
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- CuCl/TMEDA/nor-AZADO-catalyzed aerobic oxidative acylation of amides with alcohols to produce imides
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Although aerobic oxidative acylation of amides with alcohols would be a good complement to classical synthetic methods for imides (e.g., acylation of amides with activated forms of carboxylic acids), to date, there have been no reports on oxidative acylation to produce imides. In this study, we successfully developed, for the first time, an efficient method for the synthesis of imides through aerobic oxidative acylation of amides with alcohols by employing a CuCl/TMEDA/nor-AZADO catalyst system (TMEDA = teramethylethylendiamine; nor-AZADO = 9-azanoradamantane N-oxyl). The proposed acylation proceeds through the following sequential reactions: aerobic oxidation of alcohols to aldehydes, nucleophilic addition of amides to the aldehydes to form hemiamidal intermediates, and aerobic oxidation of the hemiamidal intermediates to give the corresponding imides. This catalytic system utilizes O2 as the terminal oxidant and produces water as the sole by-product. An important point for realizing this efficient acylation system is the utilization of a TMEDA ligand, which, to the best of our knowledge, has not been employed in previously reported Cu/ligand/N-oxyl systems. Based on experimental evidence, we consider that plausible roles of TMEDA involve the promotion of both hemiamidal oxidation and regeneration of an active CuII-OH species from a CuI species. Here promotion of hemiamidal oxidation is particularly important. Employing the proposed system, various types of structurally diverse imides could be synthesized from various combinations of alcohols and amides, and gram-scale acylation was also successful. In addition, the proposed system was further applicable to the synthesis of α-ketocarbonyl compounds (i.e., α-ketoimides, α-ketoamides, and α-ketoesters) from 1,2-diols and nucleophiles (i.e., amides, amines, and alcohols).
- Kataoka, Kengo,Wachi, Keiju,Jin, Xiongjie,Suzuki, Kosuke,Sasano, Yusuke,Iwabuchi, Yoshiharu,Hasegawa, Jun-Ya,Mizuno, Noritaka,Yamaguchi, Kazuya
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p. 4756 - 4768
(2018/06/07)
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- Stereoselective amination of 5-substituted γ-lactones and γ-lactams - A convenient route for the preparation of 5-substituted (3S,5S)-3- acetylaminotetrahydrofuran-2-ones and (3S,5S)-3-acetylaminopyrrolidin-2-ones
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5-Substituted (S)-tetrahydrofuran-2-ones (1a,b) and (S)pyrrolidin-2- ones (1c,d) were transformed in three steps, by treatment with tert- butoxybis(dimethylamino)methane (Bredereck's reagent), followed by nitrosation and stereoselective catalytic hydrogenation, into the corresponding 5-substituted (3S,5S)-3-acetylaminotetrahydrofuran-2-ones (4a,b) and (3S,5S)-3-acetylaminopyrrolidin-2-ones (4c,d).
- Skof, Marko,Svete, Jurij,Kmetic, Matej,Golic-Grdadolnik, Simona,Stanovnik, Branko
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p. 1581 - 1584
(2007/10/03)
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- Stereoselective 1,3-dipolar cycloadditions to (s)-1-benzoyl-3- (cyanomethylidene)-5-(methoxycarbonyl)pyrrolidin-2-one
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(5S)-1-Benzoyl-3-[(E)-cyanomethylidene]-5-(methoxycarbonyl)pyrrolidin- 2-one (5) was prepared in four steps from L-pyroglutamic acid (1). 1,3- Dipolar cycloadditions of diazomethane (6) and 2,4,6-trimethoxybenzonitrile oxide (7) gave substituted 1,2,7-triazaspiro[4,4]non-1-en-6-one 12 and 1- oxa-2,7-diazaspiro[4,4]non-1-en-6-one 13 in 38 and 20% de, respectively. On the other hand, reaction of 5 with N-phenylbenzonitrile imines 8 and 9, generated in situ from the corresponding hydrazonoyl chlorides 10 and 11, respectively, and Et3N, furnished racemic pyrrolo[3,4-c]pyrazoles 14 and 15 in 61 and 56% de, respectively. Cycloaddition of nitrile oxide 7, when performed in the presence of Et3N, led to pyrrolo[3,4-d]isoxazole 16 in 85% de.
- Skof, Marko,Svete, Jurij,Stanovnik, Branko,Golic, Ljubo,Golic-Grdadolnik, Simona,Selic, Lovro
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p. 2332 - 2340
(2007/10/03)
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- The Demonstration of Selective Peptide Bond Formation in Clear Aqueous Solutions
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The distribution of dipeptides upon treatment of equimolar amounts of glutamic acid, leucine, and C6H11N=C=N(CH2)3+NMe3-OSO2C6H4Me-p, in clear aqueous solution followed by N,C-protection, was found to be: Bz-Glu(γ-OMe)-Leu-OMe (72percent), Bz-Glu(α-OMe)-Glu-di-OMe (15percent), and Bz-Leu-Leu-OMe (8percent); Bz-Leu-Glu-di-OMe, Bz-Glu(α-OMe)-Leu-OMe, and Bz-Glu(γ-OMe)-Glu-di-OMe could not be detected (Bz = PhCO).
- Ranganathan, Darshan,Singh, Girij Pal
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p. 142 - 143
(2007/10/02)
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- Oxidation of N-Acyl-Pyrrolidines and -Piperidines with Iron(II)-Hydrogen Peroxide and an Iron Complex-Molecular Oxygen
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The reactions of N-acyl-pyrrolidines (1a-c) and -piperidines (1d-f) with Fe(II)-hydrogen peroxide in aqueous 95percent acetonitrile gave the corresponding pyrrolidin-2-ones (2a-c) and piperidin-2-ones (2d-f).The lactams (2a-f) were also the products in the oxidation of (1a-f) with molecular oxygen in the presence of an iron complex, either or , in aqueous 90percent pyridine.
- Murata, Satoru,Miura, Masahiro,Nomura, Masakatsu
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p. 1259 - 1262
(2007/10/02)
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- A ONE STEP SYNTHESIS OF 1,4-BENZODIAZEPINES:SYNTHETIC STUDIES ON NEOTHRAMYCIN
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A one step synthesis of 1,4-benzodiazepines from o-haloanilines and amino acids was achieved by use of palladium catalyzed carbonylation, by which application a synthesis of the model compounds (23a and 23b) of Neothramycin (A and B) was described.An efficient chemoselective reduction of the amide was provided.
- Mori, Miwako,Kimura, Masaya,Uozumi, Yasuhiro,Ban, Yoshio
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p. 5947 - 5950
(2007/10/02)
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