- Optical resolution of 2-azabicyclo[2.2.1]hept-5-en-3-one by inclusion complexation with brucine
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A simple optical resolution method of 2-azabicyclo[2.2.1]hept-5-en-3-one by inclusion complexation with brucine was reported. The crystal structure of the inclusion complex was analyzed by X-Ray diffraction in order to elucidate the mechanism of the efficient chiral recognition in the inclusion crystals.
- Tanaka, Koichi,Kato, Masako,Toda, Fumio
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- A Facile Lipase-Catalyzed Resolution of 2-Azabicyclohept-5-en-3-ones
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The lipase-catalyzed asymmetric synthesis of optically active 2-azabicyclohept-5-en-3-ones is reported.Chiral 2-azabicyclohept-5-en-3-ones were obtained conveniently by lipase-catalyzed enantioselective transesterification of 2-hydroxymethyl-2-azabicyclohept-5-en-3-one.
- Nakano, Hiroto,Okuyama, Yuko,Iwasa, Kazuto,Hongo, Hiroshi
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- Green access to chiral Vince lactam in a buffer-free aqueous system using a newly identified substrate-tolerant (-)-γ-lactamase
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A novel non-heme chloroperoxidase (SvGL) with promiscuous (-)-γ-lactamase activity towards Vince lactam was identified from Streptomyces viridochromogenes by genome data-mining. SvGL possesses high activity and excellent thermal stability and enantioselectivity. Furthermore, it is able to tolerate extremely high substrate concentrations (4.0 M, 436.5 g L-1). Using the newly discovered (-)-γ-lactamase as a biocatalyst, an efficient and environmentally benign process for the production of (+)-γ-lactam was developed. The process allowed an enantioselective resolution of 436.5 g L-1 racemic γ-lactam with only 0.2 g L-1 lyophilized cell-free extract, affording an extremely high substrate/catalyst ratio of 2183 (g g-1), a space-time yield of 458 g L-1 d-1, and a very low E factor (environmental factor) of 5.7 (kg waste per kg product) even when the process water is included.
- Yin, Jin-Gang,Gong, Yi,Zhang, Xiao-Yan,Zheng, Gao-Wei,Xu, Jian-He
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- Promiscuous (+)-γ-lactamase activity of an amidase from nitrile hydratase pathway for efficient synthesis of carbocyclic nucleosides intermediate
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Based on bioinformatics analysis, the promiscuous (+)-γ-lactamase activity of an amidase was identified in Rhodococcus erythropolis PR4 and found to be involved in the nitrile hydratase pathway. The amidase is highly enantioselective and can be used in the kinetic resolution of the Vince lactam. The known structure provides a rare insight into the catalytic mechanism of (+)-γ-lactamase with absolute chiral selectivity. This lactamase was cloned, purified, biochemically characterized, and demonstrated to be an ideal catalyst for the preparation of carbocyclic nucleosides of pharmaceutical interest. The chiral selectivity of this enzyme was investigated by molecular docking and site-specific mutagenesis, which provides a foundation for further engineering of these versatile biocatalysts.
- Li, Hongxia,Zhu, Shaozhou,Zheng, Guojun
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- Synthesis of rigid bicycloheterocyclic scaffolds from Vince's lactam (enzymatic resolution of Vince's lactam)
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Vince's lactam, on oxidative cleavage and reduction, produced the 3,5-dihydroxymethylpyrrolidin-2-one derivative. This precursor has been utilized in intramolecular cyclization reactions to design some unique diaza-, oxaaza-, and thiaaza-bicyclic molecules as potential scaffolds in combinatorial chemistry.
- Gurjar, Mukund K.,Bera, Smritilekha,Joshi, Rohini R.,Joshi, Ramesh A.
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- Chemical preparation method of 2-azabicyclo [2.2.1] hept-5-ene-3-one with optical activity
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The invention discloses a chemical preparation method of 2-azabicyclo [2.2.1] hept-5-ene-3-one with optical activity. The chemical preparation method comprises the following steps: racemic 2-azabicyclo [2.2.1] hept-5-ene-3-one which is easily available on the market is used as a raw material and is subjected to chemical resolution to obtain (+/-) 4-aminocyclopent-2-ene-1-carboxylic acid methyl ester with optical activity, (+/-) 4-aminocyclopent-2-ene-1-carboxylic acid is prepared by hydrolysis, and the (+/-) 4-aminocyclopent-2-ene-1-carboxylic acid is subjected to intramolecular condensation to obtain the 2-azabicyclo [2.2.1] hept-5-ene-3-one with optical activity. The method has the advantages that the use of an enzyme fermentation method is avoided, the repeatability is good, and the yield is high.
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- Enhanced enzymatic synthesis of the enantiopure intermediate for the blockbuster drug intermediate abacavir through a two-step enzymatic cascade reaction
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A very efficient enzymatic two-step cascade reaction was devised (E?>?200) for the resolution of activated γ-lactams (±)-1 and (±)-2. The N-hydroxymethyl group worked as a traceless activating group, when the reactions were performed with H2O (0.5?equiv) in the presence of benzylamine (1?equiv) in i-Pr2O at 60?°C. The ring-opened enantiomerically pure γ-amino acids (1S,4R)-6 (ee?=?99%, intermediate of abacavir) and (1S,3R)-8 (ee?=?99%) and unreacted lactams (1S,4R)-1 and (1R,4S)-2 (ee???96%) were obtained in good yields (?43%). Treatment of (1S,4R)-1 and (1R,4S)-2 with 18% HCl or NH4OH resulted in (1R,4S)-6·HCl and (1S,3R)-8·HCl or (1S,4R)-3 and (1R,4S)-4 quantitatively, with ee???96%.
- Galla, Zsolt,Forró, Enik?,Fül?p, Ferenc
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p. 729 - 731
(2016/08/01)
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- Study on immobilization of (+) γ-lactamase using a new type of epoxy graphene oxide carrier
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In this article, a new type of graphene oxide material was obtained by modification with epoxy chloropropane, which was used for the (+) γ-lactamase immobilization research. The enzymatic properties of the immobilized (+) γ-lactamase were systematically tested and compared with those of the free enzyme. The free and immobilized enzymes have the same optimum temperature (80 °C) and pH (8.0), the range of pH tolerance increased from pH 8.0-9.0 to pH 4.0-10.0 after immobilization, and the immobilized enzyme is less tolerant to heat than the free enzyme. Kinetic experiments showed that the Km value of the immobilized enzyme was about 2.66 times higher than that of the free enzyme, whereas Vmax decreased 40%. Subsequently, the apparent activation energies (Ea) of the free and immobilized enzymes became 40.03 and 35.62 kJ/mol, respectively. Finally, a reusability assay demonstrated that 70% of the enzyme activity remained after 15 repeated batch experiments.
- Li, Wei,Wen, Huijiao,Shi, Qianqiao,Zheng, Guojun
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p. 270 - 276
(2016/02/05)
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- HPLC enantioseparation on a homochiral MOF-silica composite as a novel chiral stationary phase
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The last frontier in the development of chiral stationary phases for chromatographic enantioseparation involves homochiral metal-organic frameworks (MOFs). Using enantiopure (R)-2,2′-dihydroxy-1,1′-binaphthalene-6,6′-dicarboxylic acid as a starting material, we prepared three homochiral MOFs that were further used as chiral stationary phases for high-performance liquid chromatography to separate the enantiomers of various kinds of racemic sulfoxides, sec-alcohols, β-lactams, benzoins, flavanones and epoxides. The experimental results showed excellent performances for enantioseparation, and highlighted that enantioseparation on homochiral MOF columns is practical.
- Tanaka, Koichi,Muraoka, Toshihide,Otubo, Yasuhiro,Takahashi, Hiroki,Ohnishi, Atsushi
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p. 21293 - 21301
(2016/03/08)
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- Synthesis and Fungistatic Activity of Bicyclic Lactones and Lactams against Botrytis cinerea, Penicillium citrinum, and Aspergillus glaucus
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Six analogues of natural trans-4-butyl-cis-3-oxabicyclo[4.3.0]nonan-2-one (3) and three derivatives, 11, 12, and 13, of Vince lactam (10) were synthesized and tested as fungistatic agents against Botrytis cinerea AM235, Penicillium citrinum AM354, and six strains of Aspergillus. Moreover, bioresolution carried out by means of whole cell microorganisms and commercially available enzymes afforded opposite enantiomerically enriched (a) and (+) isomers of Vince lactam (10), respectively. The effect of compound structures and stereogenic centers on biological activity has been discussed. The highest fungistatic activity was observed for four lactones: 3, 4, 7, and 8 (IC50 = 104.6-115.2 g/mL) toward B. cinerea AM235. cis-5,6-Epoxy-2-aza[2.2.1]heptan-3-one (13) indicated significant fungistatic activity (IC50 = 107.1 g/mL) against Aspergillus glaucus AM211. trans-4-Butyl-cis-3-oxabicyclo[4.3.0]nonan-2-one (3) and trans-4-butyl-cis-3-oxabicyclo[4.3.0]non-7-en-2-one (7) exhibited high fungistatic activity (IC50 = 143.2 and 110.2 g/mL, respectively) against P. citrinum AM354 as well.
- Walczak, Paulina,Pannek, Jakub,Boratynski, Filip,Janik-Polanowicz, Agata,Olejniczak, Teresa
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p. 8571 - 8578
(2015/04/22)
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- Enzymatic preparation of optically pure (+)-2-azabicyclo[2.2.1]hept-5-en-3-one by (-)-γ-lactamase from Bradyrhizobium japonicum USDA 6
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Whole cells of Bradyrhizobium japonicum USDA 6 showed both (+)-γ-lactamase activity and (-)-γ-lactamase activity. Insight into the genome of B. japonicum USDA 6 revealed two potential γ-lactamases: a type I (+)-γ-lactamase and a (-)-γ-lactamase, making it the first strain to contain two totally different enantioselective lactamases. Both recombinant enzymes could easily be used to prepare either optically pure (+)-γ-lactam ((+)-2-azabicyclo[2.2.1]hept-5-en-3-one) or optically pure (-)-γ-lactam ((-)-2-azabicyclo[2.2.1]hept-5-en-3-one), which are versatile synthetic building blocks for the synthesis of various carbocyclic nucleosides and carbocyclic sugar analogues. Bioinformatic analysis showed that the type I (+)-γ-lactamase belongs to the amidase signature family, with 504 amino acids; the (-)-γ-lactamase, which consists of 274 amino acids, belongs to the hydrolase family. Here, we report that B. japonicum USDA contains a (-)-γ-lactamase in addition to a (+)-γ-lactamase, and it is the (-)-γ-lactamase from this strain that is examined in detail in this Letter. Enzymatic synthesis of optically pure (+)-γ-lactam with nearly 50% isolated yield and >99% ee was achieved.
- Zhu, Shaozhou,Ren, Lu,Yu, Songzhu,Gong, Cuiyu,Song, Dawei,Zheng, Guojun
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p. 4899 - 4902
(2015/02/19)
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- Identification and application of enantiocomplementary lactamases for Vince lactam derivatives
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Four enzymes showing hydrolytic activity on derivatives of 2-azabicyclo[2.2.1]hept-5-en-3-one (Vince lactam) were successfully identified through analysis of protein crystal structure and amino acid sequence alignments. Enantiocomplementary activities were observed on Vince lactam and its saturated analog 2-azabicyclo[2.2.1]heptan-3-one with non-heme chloroperoxidase (CPO-T) from Streptomyces aureofaciens, cyclic imide hydrolase (CIH) from Pseudomonas putida, polyamidase (NfpolyA) from Nocardia farcinica, and amidase (AMI) from Rhodococcus globerulus, and perfect kinetic resolution was achieved (E>200). Computational analysis of amide bond resonance stabilization in lactams correlated well with the overall reactivity pattern of the lactams as a function of ring size and strain. The biocatalysts cloned and investigated in this study could be of interest for the synthesis of enantiopure carbocyclic nucleoside analogues.
- Assaf, Zeinab,Eger, Elisabeth,Vitnik, Zeljko,Fabian, Walter M. F.,Ribitsch, Doris,Guebitz, Georg M.,Faber, Kurt,Hall, Mélanie
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p. 2517 - 2521
(2015/04/14)
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- Asymmetric biocatalysis of S-3-amino-3-phenylpropionic acid with new isolated Methylobacterium Y1-6
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β-amino acids are widely used in drug research, and S-3-amino-3-phenylpropionic acid (S-APA) is an important pharmaceutical intermediate of S-dapoxetine, which has been approved for the treatment of premature ejaculation. Chiral catalysis is an excellent method for the preparation of enantiopure compounds. In this study, we used (±)-ethyl-3-amino-3-phenylpropanoate (EAP) as the sole carbon source. Three hundred thirty one microorganisms were isolated from 30 soil samples, and 17 strains could produce S-APA. After three rounds of cultivation and identification, the strain Y1-6 exhibiting the highest enantioselective activity of S-APA was identified as Methylobacterium oryzae. The optimal medium composition contained methanol (2.5 g/L), 1,2-propanediol (7.5 g/L), soluble starch (2.5 g/L), and peptone (10 g/L); it was shaken at 220 rpm for 4-5 days at 30 C. The optimum condition for biotransformation of EAP involved cultivation at 37 C for 48 h with 120 mg of wet cells and 0.64 mg of EAP in 1 ml of transfer solution. Under this condition, substrate ee was 92.1% and yield was 48.6%. We then attempted to use Methylobacterium Y1-6 to catalyze the hydrolytic reaction with substrates containing 3-amino-3-phenyl-propanoate ester, N-substituted-β-ethyl-3-amino-3-phenyl-propanoate, and γ-lactam. It was found that 5 compounds with ester bonds could be stereoselectively hydrolyzed to S-acid, and 2 compounds with γ-lactam bonds could be stereoselectively hydrolyzed to (-)-γ-lactam.
- Li, Yi,Wang, Wenfu,Huang, Yumian,Zou, Qianwen,Zheng, Guojun
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p. 1674 - 1678
(2013/11/19)
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- Synthesis of regio-and stereoisomers of highly functionalized 1,2,3-triazole-substituted cyclopentanes
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Highly functionalized regio-and stereoisomers of 1,2,3-triazole-substituted cyclopentanes were prepared in six steps from either bicyclic β-lactam 7 or γ-lactam 23 by 1,3-dipolar cycloaddition of the azido cyclopentanol intermediates with acetylenes. The reactions of azido aminocyclopentanols with non-symmetric acetylenes resulted regioselectively in the corresponding 1,4-disubstitued triazole derivatives under both thermal and Cu(I)-catalysed conditions. These compounds can be regarded as highly functionalized 1,2,3-triazole-modified carbocyclic nucleoside analogues.
- Kiss, Lorand,Forro, Eniko,Fueloep, Ferenc
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scheme or table
p. 220 - 228
(2012/04/23)
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- Synthesis of conformationally restricted 1,2,3-triazole-substituted ethyl β- and γ-aminocyclopentanecarboxylate stereoisomers. Multifunctionalized alicyclic amino esters
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Stereoisomers of 1,2,3-triazole-functionalized, conformationally restricted β- or γ-amino esters with a cyclopentane skeleton were efficiently synthetized from the bicyclic β-lactam 6-azabicyclo[3.2.0]hept-3-en-7-one (1) and Vince γ-lactam (15) in five or six steps involving the azide-alkyne 1,3-dipolar cycloaddition of azido-substituted amino ester stereoisomers with nonsymmetric acetylenes. The azide-alkyne click reactions were investigated under thermal and Cu(I)-catalyzed conditions. Surprisingly, the thermally induced cycloaddition furnished the corresponding 1,4-triazoles regioselectively, which also took place selectively in response to Cu(I) catalysis.
- Kiss, Loránd,Forró, Eniko,Sillanp??, Reijo,Fül?p, Ferenc
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experimental part
p. 3599 - 3607
(2010/06/21)
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- Synthesis of highly functionalized cyclopentanes as precursors of hydroxylated azidocarbonucleosides
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Regio- and stereoisomers of functionalized azido amino alcohols with a cyclopentane skeleton were synthesized in enantiomerically pure forms. Enzymatic ring cleavage of racemic2-azabicyclo[2.2.1]hept-5-en-3-one gave the corresponding amino acid and one enantiomer of the lactam stereospecifically. These were protected by esterification and carbamoylation, and then epoxidized. The resulting oxiranes underwent cleavage by sodium azide with complementary stereoselectivities. The regioisomeric products were easily separated by crystallization or column chromatography.
- Kiss, Lorand,Forro, Enikoe,Sillanpaeae, Reijo,Fueloep, Ferenc
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scheme or table
p. 153 - 160
(2010/04/02)
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- Enzymatic method for the synthesis of blockbuster drug intermediates - Synthesis of five-membered cyclic γ-amino acid and γ-lactam enantiomers
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A very efficient enzymatic method was developed for the synthesis of cyclic γ-lactam and γ-amino acid enantiomers, intermediates for drugs with a prominent turnover (e.g., abacavir and carbovir), through the CAL-B-catalysed enantioselective (E > 200) hydrolysis of the corresponding N-Boc protected and unprotected racemic γ-lactams with H2O in iPr2O. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Forro, Eniko,Fueloep, Ferenc
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scheme or table
p. 5263 - 5268
(2009/06/18)
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- Substituted cyclopentane and cyclopentene compounds useful as neuraminidase inhibitors
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Compounds I-III wherein U is CH, O, or S; Z is mono- or di-substituted carbon; R is (CH2)nCO2H, (CH2)nSO3H, (CH2)nPO3H2, (CH2)nNO2, CH(SCH3)3, esters; R1 is H, hydroxyalkyl, aminoalkyl, alkoxyalkyl; RR1 is O; n is 0-4; R2, R3 is H, hydroxyalkyl, aminoalkyl, alkoxyalkyl, haloalkyl; R4 is (CH2)nOH, (CH2)nNH2, substituted alkyl were prepd. as neuraminidase inhibitors. Thus, (1R,3R,4R,1′S)-(?)-(1′-acetylamino-2 ′-ethyl)butyl-4-(aminoimino)methylaminocyclopentan-1-carboxylic acid was prepd. and tested in vitro as neuraminidase inhibitor (IC501μM).
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- Inversion of enantioselectivity in the Diels-Alder synthesis of 2-azabicyclo[2.2.1]hept-5-en-3-one from cyclopentadiene and chiral sulfonyl cyanides
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Diels-Alder cycloaddition of (1R,3S,4S)-3-menthanesulfonyl cyanide to cyclopentadiene, followed by treatment with AcOH/H2O, afforded an 11 % ee of (+)-(1S)-2-azabicyclo[2.2.1]hept-5-en-3-one [(+)-ent;-1]. The analogous process from (1R,3R,4S)-3-menthanesulfonyl cyanide afforded an estimated 12% ee of (-)-1.
- Blanco, Jose M.,Caamano, Olga,Fernandez, Franco,Garcia-Mera, Xerardo,Nieto, Isabel,Rodriguez-Borges, Jose E.
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p. 1745 - 1750
(2007/10/03)
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- Nonreductive enantioselective ring opening of N-(methylsulfonyl)dicarboximides with diisopropoxytitanium α,α,α′,α′-tetraaryl-1,3-dioxolane-4,5- dimethanolate
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The bicyclic and tricyclic meso-N-(methylsulfonyl)dicarboximides 1a-f are converted enantioselectively to isopropyl [(sulfonamido)carbonyl]-carboxylates 2a-f by diisopropoxytitanium TADDOLate (75-92% yield; see Scheme 3). The enantiomer ratios of the products are between 86:14 and 97:3, and recrystallization from CH2Cl2/hexane leads to enantiomerically pure sulfonamido esters 2 (Scheme 3). The enantioselectivity shows a linear relationship with the enantiomer excess of the TADDOL employed (Fig. 3). Reduction of the ester and carboxamide groups (LiAlH4) and additional reductive cleavage of the sulfonamido group (Red-Al) in the products 2 of imide-ring opening gives hydroxy-sulfonamides 3 and amino alcohols 4, respectively (Scheme 4). The absolute configuration of the sulfonamido esters 2 is determined by chemical correlation (with 2a, b; Scheme 6), by the X-ray analysis of the camphanate of 3e (Fig. I), and by comparative 19F-NMR analysis of the Mosher esters of the hydroxy-sulfonamides 3 (Table I). A general proposal for the assignment of the absolute configuration of primary alcohols and amines of Formula HXCH2CHR1R2, X = O, NH, is suggested (see 11 in Table I). It follows from the assignment of configuration of 2 that the Re carbonyl group of the original imide 1 is converted to an isopropyl ester group. This result is compatible with a rule previously put forward for the stereochemical course of reactions involving titanium TADDOLate activated chelating electrophiles (12 in Scheme 7). A tentative mechanistic model is proposed (13 and 14 in Scheme 7).
- Ramon, Diego J.,Guillena, Gabriela,Seebach, Dieter
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p. 875 - 894
(2007/10/03)
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- Lipase-catalyzed resolution of 2-azabicyclo[2.2.1]hept-5-en-3-ones
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The lipase-catalyzed asymmetric resolution of 2-azabicyclo[2.2.1]hept-5-en-3-ones is reported; non-racemic chiral 2-azabicyclo[2.2.1]hept-5-en-3-ones were obtained conveniently by lipase-catalyzed enantioselective transesterification or hydrolysis of N-hydroxymethyl-2-azabicyclo[2.2.1]hept-5-en-3-one or N-acyloxymethyl-2-azabicyclo[2.2.1]hept-5-en-3-one.
- Nakano, Hiroto,Iwasa, Kazuto,Okuyama, Yuko,Hongo, Hiroshi
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p. 2381 - 2386
(2007/10/03)
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- Conversion of one enantiomer of the carbocyclic nucleoside synthon 2-azabicyclohept-5-en-3-one into the other
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The lactam synthon 2-azabicyclohept-5-en-3-one was converted into its enantiomer by a 5-step sequence incorporating a skeletal rearrangement mediated by anchimeric assistance of the nitrogen atom; the route proceeded via a tosylate intermediate prone to racemization.
- Palmer, Christopher F.,McCague, Raymond
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p. 1201 - 1204
(2007/10/02)
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- Development of the Biocatalytic Resolution of 2-azabicyclohept-5-en-3-one as an entry to Single-Enantiomer Carbocyclic Nucleosides
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For the resolution of the bicyclic lactam 2-azabicyclohept-5-en-3-one, efficient whole cell biocatalysts have been identified and from these, enzymes (lactamases) have been isolated.While the two enzymes obtained act on different enantiomers of the lactam, either can be used in scaleable processes to obtain synthons for carbocyclic nucleosides having the natural configuration.
- Taylor, Stephen J C,McCague, Raymond,Wisdom, Richard,Lee, Carol,Dickson, Karen,et al.
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p. 1117 - 1128
(2007/10/02)
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