- Concise stereoselective total synthesis of (+)-muricatacin and (+)-epi-muricatacin
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Efficient stereoselective total synthesis of (+)-muricatacin (1) and (+)-epi-muricatacin (8) was accomplished from commercially available chemical pent-4-ynoic acid via Shi's asymmetric epoxidation and Mitsunobu reaction as the key steps in 17.8% and 26.9
- Dong, Hong-Bo,Yang, Ming-Yan,Liu, Bin,Wang, Ming-An
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Read Online
- A convenient synthesis of L-ribose from D-fructose
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An efficient method for the stereoselective synthesis of L-ribose was accomplished starting from commercially inexpensive D-fructose. The intermediates in the process can serve as versatile precursors for the preparation of L-nucleoside analogues.
- Perali, Ramu Sridhar,Mandava, Suresh,Bandi, Ramakrishna
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Read Online
- Biosynthesis of 1-deoxy-l-imino-D-erythrose 4-phosphate: A defining metabolite in the aminoshikimate pathway
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With respect to the source of the nitrogen atom incorporated into the aminoshikimate pathway, d-erythrose 4-phosphate has been proposed to undergo a transamination reaction resulting in formation of 1-deoxy-1-imino-d-erythrose 4-phosphate. Condensation of this metabolite with phosphoenolpyruvate catalyzed by aminoDAHP synthase would then hypothetically form the 4-amino-3,4-dideoxy-D-arabino-heptulosonic acid 7-phosphate (aminoDAHP), which is the first committed intermediate of the aminoshikimate pathway. However, in vitro formation of aminoDAHP has not been observed. In this account, the possibility is examined that 3-amino-3-deoxy-d-fructose 6-phosphate is the source of the nitrogen atom of the aminoshikimate pathway. Transketolase-catalyzed ketol transfer from 3-amino-3-deoxy-d-fructose 6-phosphate to d-ribose 5-phosphate would hypothetically release 1-deoxy-1-imino-d-erythrose 4-phosphate. Along these lines, a chemoenzymatic synthesis of 3-amino-3-deoxy-d-fructose 6-phosphate was elaborated. Incubation of 3-amino-3-deoxy-d-fructose 6-phosphate in Amycolatopsis mediterranei crude cell lysate with d-ribose 5-phosphate and phosphoenolpyruvate resulted in the formation of aminoDAHP and 3-amino-5-hydroxybenzoic acid. 3-[15N]-Amino-3-deoxy-D-6,6-[2H2]-fructose 6-phosphate was also synthesized and similarly incubated in A. mediterranei crude cell lysate. Retention of both 15N and 2H2 labeling in product aminoDAHP indicates that 3-amino-3-deoxy-D-fructose 6-phosphate is serving as a sequestered form of 1-deoxy-1-imino-D-erythrose 4-phosphate. Copyright
- Guo, Jiantao,Frost
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Read Online
- Studies on asymmetric total synthesis of (?)-β-hydrastineviaa chiral epoxide ring-opening cascade cyclization strategy
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Herein, facile and enantioselective approaches to synthesize the core phthalide tetrahydroisoquinoline scaffold of (?)-β-hydrastineviaboth a CF3COOH-catalyzed (86% ee) and KHMDS-catalyzed (78% ee) epoxide ring-opening/transesterification cascade cyclization from chiral epoxide under very mild conditions are described. The key elements include a highly enantioselective epoxidation using the Shi ketone catalyst and an intramolecular CF3COOH-catalyzed cascade cyclization in one pot, and a late-stage C-3′ epimerization under MeOK/MeOH conditions as the key steps to achieve the first total synthesis of (?)-β-hydrastine (up to 81% ee).
- Cheng, Maosheng,Li, Jihui,Liu, Yongxiang,Meng, Jiaxin,Qin, Qiaohua,Song, Xinjing,Wu, Tianxiao,Zhao, Dongmei,Zheng, Yang
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p. 18953 - 18958
(2020/06/08)
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- IMPROVED SYNTHESIS OF AN EPOXIDATION-CATALYST
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The present invention relates to an improved process to produce a specific and very efficient epoxidation-catalyst (1,2:4,5-Di-O-isopropylidene-β-D-erythro-2,3-hexodiulo-2,6-pyranose).
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Page/Page column 7; 8
(2020/07/14)
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- Safe and Scalable Aerobic Oxidation by 2-Azaadamantan-2-ol (AZADOL)/NOx Catalysis: Large-Scale Preparation of Shi's Catalyst
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A method for safe and scalable aerobic alcohol oxidation using 2-azaadamantan-2-ol (AZADOL), an azaadamantane-type hydroxylamine catalyst, with a NOx cocatalyst in a conventional batch reactor has been developed. The use of 2 mol % AZADOL and 10 mol % NaNO2 was determined to promote aerobic alcohol oxidation quantitatively within a reasonable time (8 h). Safety is ensured by controlling the reaction temperature below the flash point of the acetic acid solvent. The robustness of the developed method is demonstrated by the 500 g scale oxidation of diacetone fructose into Shi's catalyst for asymmetric epoxidation.
- Sasano, Yusuke,Sato, Hikaru,Tadokoro, Shinsuke,Kozawa, Masami,Iwabuchi, Yoshiharu
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p. 571 - 577
(2019/03/19)
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- Synthesis method of fructose-derived chiral ketone catalyst
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The invention provides a synthesis method of a fructose-derived chiral ketone catalyst. The method comprises the following steps: (1) by using D-fructose and acetone as a raw material, carrying out ketonization reaction at 10-45 DEG C by using concentrated sulfuric acid as a catalyst to obtain a first intermediate; (2) dissolving the first intermediate in an organic solvent, adding molecular sieve powder, and carrying out oxidation at 50-80 DEG C by using PCC as an oxidant, thereby obtaining a second intermediate; (3) carrying out hydrolysis on the second intermediate at 10-45 DEG C under the actions of acetic acid, water and zinc chloride, thereby obtaining a third intermediate; after the hydrolysis finishes, adding acetic anhydride, and carrying out esterification reaction to obtain a fructose-derived chiral ketone hydrate; and (4) eliminating water molecules in the fructose-derived chiral ketone hydrate by using a polar organic solvent, thereby obtaining the fructose-derived chiral ketone. The method has the advantages of simple technique, low raw material cost and mild reaction conditions, is convenient for separation and purification, can be used for quickly and efficiently synthesizing the fructose-derived chiral ketone catalyst, and is more suitable for industrial production.
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Paragraph 0012; 0013; 0014; 0031; 0032; 0033
(2016/10/10)
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- An alkoxyamine compound, alkoxy alcohol oxidation catalyst and method of using the alcohol oxidation
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PROBLEM TO BE SOLVED: To provide a novel alkoxyamine compound which can be easily manufactured and applied suitably as an alcohol oxidation catalyst capable of exerting sufficiently high catalytic activity in oxidation of primary and secondary alcohols.SOLUTION: There is provided an alkoxyamine compound with a homoadamantane skeleton represented by the general formula (1) in the figure. [In the formula (1), Rand Rare each independently any one selected from the group consisting of a hydrogen atom and alkyl groups that may be substituted.
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Paragraph 0096; 0099-0100
(2017/02/02)
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- Highly efficient aerobic oxidation of alcohols by using less-hindered nitroxyl-radical/copper catalysis: Optimum catalyst combinations and their substrate scope
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The oxidation of alcohols into their corresponding carbonyl compounds is one of the most fundamental transformations in organic chemistry. In our recent report, 2-azaadamantane N-oxyl (AZADO)/copper catalysis promoted the highly chemoselective aerobic oxidation of unprotected amino alcohols into amino carbonyl compounds. Herein, we investigated the extension of the promising AZADO/copper-catalyzed aerobic oxidation of alcohols to other types of alcohol. During close optimization of the reaction conditions by using various alcohols, we found that the optimum combination of nitroxyl radical, copper salt, and solution concentration was dependent on the type of substrate. Various alcohols, including highly hindered and heteroatom-rich ones, were efficiently oxidized into their corresponding carbonyl compounds under mild conditions with lower amounts of the catalysts.
- Sasano, Yusuke,Kogure, Naoki,Nishiyama, Tomohiro,Nagasawa, Shota,Iwabuchi, Yoshiharu
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p. 1004 - 1009
(2015/03/31)
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- Efficient magnetic and recyclable SBILC (supported basic ionic liquid catalyst)-based heterogeneous organocatalysts for the asymmetric epoxidation of trans-methylcinnamate
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A green alternative, based on the use of an efficient and recyclable chiral ketone@SBILC@MWCNT@Fe3O4 catalytic system (Y = 35%, S = 100% and ee = 100%), was developed for the asymmetric epoxidation of trans-methylcinnamate to (2R,3S)
- Candu,Rizescu,Podolean,Tudorache,Parvulescu,Coman
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p. 729 - 737
(2015/02/19)
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- Stable TEMPO and ABNO Catalyst Solutions for User-Friendly (bpy)Cu/Nitroxyl-Catalyzed Aerobic Alcohol Oxidation
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Two solutions, one consisting of bpy/TEMPO/NMI and the other bpy/ABNO/NMI (bpy =2,2′-bipyridyl; TEMPO = 2,2,6,6-tetramethylpiperidine N-oxyl, ABNO = 9-azabicyclo[3.3.1]nonane N-oxyl; NMI = N-methylimidazole), in acetonitrile are shown to have good long-term stability (≥1 year) under air at 5 °C. The solutions may be combined in appropriate quantities with commercially available [Cu(MeCN)4]OTf to provide a convenient catalyst system for the aerobic oxidation of primary and secondary alcohols.
- Steves, Janelle E.,Stahl, Shannon S.
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p. 11184 - 11188
(2015/11/18)
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- Unprecedented 8,9′-neolignans: Enantioselective synthesis of possible stereoisomers for structural determination
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(+)-Wutaienin (3) and its C-7 methyl ether (4), isolated from Zanthoxylum wutaiense, were found to be unprecedented 8,9′-neolignans containing an (S)-2-(1,1-dimethyl-1-hydroxymethyl)-7-methoxydihydrobenzofuran skeleton. Wutaienin (3) was present in the pl
- Takahashi, Masato,Suzuki, Noriyuki,Ishikawa, Tsutomu,Huang, Hung-Yi,Chang, Hsun-Shuo,Chen, Ih-Sheng
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p. 2585 - 2589
(2015/02/05)
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- Mechanistic insight into aerobic alcohol oxidation using NOx-nitroxide catalysis based on catalyst structure-activity relationships
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The mechanism of an NOx-assisted, nitroxide(nitroxyl radical)-catalyzed aerobic oxidation of alcohols was investigated using a set of sterically and electronically modified nitroxides (i.e., TEMPO, AZADO (1), 5-F-AZADO (2), 5,7-DiF-AZADO (3), 5-MeO-AZADO (4), 5,7-DiMeO-AZADO (5), oxa-AZADO (6), TsN-AZADO (7), and DiAZADO (8)). The motivation for the present study stemmed from our previous observation that the introduction of an F atom at a remote position from the nitroxyl radical moiety on the azaadamantane nucleus effectively enhanced the catalytic activity under typical NOx-mediated aerobic-oxidation conditions. The kinetic profiles of the azaadamantane-N-oxyl-[AZADO (1)-, 5-F-AZADO (2)-, and 5,7-DiF-AZADO (3)]-catalyzed aerobic oxidations were closely investigated, revealing that AZADO (1) showed a high initial reaction rate compared to 5-F-AZADO (2) and 5,7-DiF-AZADO (3); however, AZADO-catalyzed oxidation exhibited a marked slowdown, resulting in ~90% conversion, whereas 5-F-AZADO-catalyzed oxidation smoothly reached completion without a marked slowdown. The reasons for the marked slowdown and the role of the fluoro group are discussed. Oxa-AZADO (6), TsN-AZADO (7), and DiAZADO (8) were designed and synthesized to confirm their comparable catalytic efficiency to that of 5-F-AZADO (2), providing supporting evidence for the electronic effect on the catalytic efficiency of the heteroatoms under NOx-assisted aerobic-oxidation conditions.
- Shibuya, Masatoshi,Nagasawa, Shota,Osada, Yuji,Iwabuchi, Yoshiharu
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p. 10256 - 10268
(2015/02/19)
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- A mild and highly efficient laccase-mediator system for aerobic oxidation of alcohols
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With the aid of the highly active nitroxyl radical AZADO (2-azaadamantane N-oxyl), a simple method for the aerobic catalytic oxidation of alcohols is presented. The oxidations could typically proceed under practical ambient conditions (room temperature, air atmosphere, no moisture effect, metal-free, etc.) with a broad generality of the alcohol substrates, and especially for the oxidation of complex and highly functionalized alcohols. An ionic mechanism is proposed for the present system.
- Zhu, Chenjie,Zhang, Zhi,Ding, Weiwei,Xie, Jingjing,Chen, Yong,Wu, Jinglan,Chen, Xiaochun,Ying, Hanjie
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supporting information
p. 1131 - 1138
(2014/03/21)
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- Concise synthesis of chiral N -Benzyl-α,α-Diarylprolinols through shi asymmetric epoxidation
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A concise and practical synthesis of chiral N-benzyl-α,α- diaryl-2-prolinols was developed through Shi asymmetric epoxidation, followed by double nucleophilic substitution of bromo-containing olefins. A series of enantioenriched N-benzyl-α,α-diaryl-2-prolinols were obtained with excellent enantioselectivities (96% ee) in moderate to good yields (40-76% yield). For the first time, enantiopure N-benzyl-α,α-diphenyl-2- prolinol was obtained from bromo-containing olefin using this methodology. Georg Thieme Verlag Stuttgart, New York.
- Li, Jie,Zhou, Hai,Weng, Jiangsen,Wang, Mingwen,Ge, Chengsheng,Tu, Wujie
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supporting information
p. 805 - 808
(2014/04/03)
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- 3-methyl-4-oxa-5-azahomoadamantane: Alkoxyamine-type organocatalyst for alcohol oxidation
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Strong, silent type: A novel alkoxyamine-type organocatalyst has been discovered for alcohol oxidation (see scheme). The alkoxyamine exhibits a high catalytic activity for the oxidation of alcohols to afford the corresponding carbonyl compounds in high yield by oxidative transformation into an oxoammonium ion, which is proposed to serve as an active species. Copyright
- Sasano, Yusuke,Murakami, Keiichi,Nishiyama, Tomohiro,Kwon, Eunsang,Iwabuchi, Yoshiharu
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supporting information
p. 12624 - 12627
(2013/12/04)
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- Enantioselective synthesis of (thiolan-2-yl)diphenylmethanol and its application in asymmetric, catalytic sulfur ylide-mediated epoxidation
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This work describes an expeditious and efficient preparation of enantiopure (thiolan-2-yl)diphenylmethanol (2) featuring a double nucleophilic substitution and Shi epoxidation as key steps. One of the applications of its benzyl ether derivative to asymmetric sulfur ylide-mediated epoxidation with up to 92% ee (14 examples) was also demonstrated herein.
- Wu, Hsin-Yi,Chang, Chih-Wei,Chein, Rong-Jie
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p. 5788 - 5793
(2013/07/25)
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- C-H modification of 2-azaadamantane: Synthesis of C5-functionalized AZADOs for advanced use
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Regioselective C-H functionalization of N-protected 2-azaadamantane was achieved via a radical-induced bromination. The obtained 5-bromo-2-azaadamantane is readily transformed to arylated/alkylated 2-azaadamantane N-oxyls [AZADOs], which exhibit high catalytic activities for alcohol oxidation. The Japan Institute of Heterocyclic Chemistry.
- Sasano, Yusuke,Nishiyama, Tomohiro,Tomizawa, Masaki,Shibuya, Masatoshi,Iwabuchi, Yoshiharu
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p. 2109 - 2118
(2013/10/22)
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- METHOD FOR OXIDIZING ALCOHOLS
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A method for oxidizing an alcohol, wherein oxidation is performed in the presence of a compound represented by the following formula (I) and a bulk oxidant, which enables efficient oxidation of secondary alcohols as well as primary alcohols, and can attain high reaction efficiency even when air is used as a bulk oxidant.
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Paragraph 0099; 0100
(2013/06/05)
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- Oxidation of alcohols to carbonyl compounds with diisopropyl azodicarboxylate catalyzed by nitroxyl radicals
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A nitroxyl-radical-catalyzed oxidation of alcohols using diisopropyl azodicarboxylate (DIAD) as the terminal oxidantis reported. A variety of primary and secondary alcohols including aliphatic, benzylic, and allylic alcohols are efficiently oxidized to their corresponding aldehydes and ketones without overoxidation to carboxylic acid. 1,2-Diols are oxidized to hydroxyl ketones or diketones depending on the amount of DIAD used.
- Hayashi, Masaki,Shibuya, Masatoshi,Iwabuchi, Yoshiharu
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experimental part
p. 3005 - 3009
(2012/05/04)
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- Highly efficient, organocatalytic aerobic alcohol oxidation
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5-Fluoro-2-azaadamantane N-oxyl (5-F-AZADO) realizes a simple, organocatalytic aerobic alcohol oxidation system that has a wide scope under mild conditions at ambient pressure and temperature and is weakly acidic and halogen- and transition-metal-free. The oxoammonium nitrate (5-F-AZADO +NO3-) works as a bifunctional catalyst of 5-F-AZADO and NOx that enables the catalytic aerobic oxidation of alcohols by itself (a metal-salt-free system).
- Shibuya, Masatoshi,Osada, Yuji,Sasano, Yusuke,Tomizawa, Masaki,Iwabuchi, Yoshiharu
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supporting information; experimental part
p. 6497 - 6500
(2011/06/23)
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- Practical preparation methods for highly active azaadamantane-nitroxyl- radical-type oxidation catalysts
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We have recently disclosed that a less hindered class of nitroxyl radicals, i.e., 2-azaadamantan-N-oxyl (AZADO), 1-Me-AZADO, and 9-azabicyclo[3.3.1]nonan- N-oxyl (ABNO), exhibit marked catalytic activity for the oxidation of alcohols with the aid of environmentally friendly oxidants, offering a green and sustainable option for current alcohol oxidation. Encouraged by their outstanding catalytic performance, we envisioned the development of scalable routes to these radicals that could be extended to the commercialization of these radicals for benchtop use as well as for industrial use as optional reagents that complement TEMPO, the flagship compound of stable nitroxyl radicals. We herein describe short and reproducible preparation methods for AZADO and 1-Me-AZADO, featuring an efficient construction of the 2-azaadamantane skeleton. 1 Introduction 2 1-Me-AZADO and AZADO: First-Generation Syntheses 3 Second-Generation Synthesis of 1-Me-AZADO 4 Synthetic Venture towards 2-Azaadamantane: Second-Generation Synthesis of AZADO 5 Conclusion. Georg Thieme Verlag Stuttgart.
- Shibuya, Masatoshi,Sasano, Yusuke,Tomizawa, Masaki,Hamada, Toshimasa,Kozawa, Masami,Nagahama, Noriaki,Iwabuchi, Yoshiharu
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scheme or table
p. 3418 - 3425
(2012/01/03)
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- 9-azanoradamantane N-Oxyl (Nor-AZADO): A highly active organocatalyst for alcohol oxidation
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A highly active organocatalyst for alcohol oxidation has been developed. 9-Azanoradamantane N-oxyl (Nor-AZADO 4), constituting an unhindered, stable nitroxyl radical, exhibits superior catalytic activity to 2,2,6,6- tetramethylpiperidine-1-oxyl (TEMPO) and AZADOs in the oxidation of alcohols to their corresponding carbonyl compounds.
- Hayashi, Masaki,Sasano, Yusuke,Nagasawa, Shota,Shibuya, Masatoshi,Iwabuchi, Yoshiharu
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experimental part
p. 1570 - 1573
(2012/01/05)
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- An expeditious entry to 9-azabicyclo[3.3.1]nonane N-oxyl (ABNO): Another highly active organocatalyst for oxidation of alcohols
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(Chemical Equation Presented) A practical, three-step synthetic route to 9-azabicyclo[3.3.1] nonane N-oxyl (ABNO, 3), an unhindered, stable class of nitroxyl radical, has been developed. ABNO exhibits a highly active nature compared with TEMPO in the catalytic oxidation of alcohols to their corresponding carbonyl compounds.
- Shibuya, Masatoshi,Tomizawa, Masaki,Sasano, Yusuke,Iwabuchi, Yoshiharu
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supporting information; experimental part
p. 4619 - 4622
(2009/09/08)
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- ALCOHOL OXIDATION CATALYST AND ITS PREPARATION PROCESS
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An alcohol oxidation catalyst which is an organic oxidation catalyst to oxidize an alcohol, which contains azabicyclo [3.3.1]nonane N-oxyl represented by the following formula (1) having an N-oxyl group incorporated in a bicycle[3.3.1]nonane skeleton: wherein X is H2, O or NOH.
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(2008/12/08)
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- PYRIMIDINE DERIVATIVES AS ANTICANCER AGENTS
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The present invention includes methods of treating or preventing cancer by administering an effective amount of 6-substituted pyrimidine derivatives of the Formula I to a subject need thereof:
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Page/Page column 47
(2008/12/07)
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- HSCN condensation with ulosides: preferred formation of carbohydrate-fused hemiaminals of the 4-hydroxy-1,3-oxazolidine-2-thione type
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Selected ulofuranosides and ulopyranosides react with thiocyanic acid to give good yields of stable carbohydrate-fused hemiaminal 1,3-oxazolidine-2-thiones.
- Silva, Sandrina,Sim?o, Ana Catarina,Tatibou?t, Arnaud,Rollin, Patrick,Rauter, Amelia Pilar
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p. 682 - 686
(2008/09/16)
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- Carbohydrate-based spiro-1,3-oxazolidine-2-thiones: stereoselective approaches using aziridines and epoxides
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D-glucose and D-fructose have been used as starting materials to prepare spiro-1,3-oxazolidine-2-thiones anchored on the third position of both carbohydrates. Following different approaches and depending on the carbohydrate template explored, stereoselect
- Tardy, Sebastien,Vicente, Joana Lobo,Tatibouet, Arnaud,Dujardin, Gilles,Rollin, Patrick
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scheme or table
p. 3108 - 3120
(2009/04/06)
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- ALCOHOL OXIDATION CATALYST AND METHOD OF SYNTHESIZING THE SAME
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An organic oxidation catalyst for alcohols which is environmentally less harmful and with which efficient oxidation can be conducted. The oxidation catalyst for alcohols is a 1-alkyl-2-azadamantan-N-oxyl which has a nitroxyl group incorporated in the adamantane skeleton and was synthesized from as a base material a bicyclic compound obtained by the Grob-type ring-opening reaction of 1,3-adamantanediol. Due to the nitroxyl group on the adamantane skeleton, the ±-position hydrogen is stabilized based on Bredt's rule and the stability of the oxoammonium group generated by the oxidation thereof is ensured. Compared to TEMPO, which is a conventional oxidation catalyst, this catalyst is reduced in steric hindrance and is usable in a wide range of reaction fields. Because of this, not only a primary alcohol but a secondary alcohol having a sterically complicated structure, which has been difficult to oxidize with TEMPO, can be oxidized at a high efficiency.
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Page/Page column 12-14
(2008/06/13)
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- ODCASE INHIBITORS FOR THE TREATMENT OF MALARIA
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The present invention includes methods of treating or preventing malaria by administering an anti-malarial effective amount of 6-substituted uridine derivatives to a subject need thereof. The invention also includes new 6-substituted uridine derivatives for use as therapeutics, in particular to treat malaria.
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Page/Page column 46; 47
(2008/06/13)
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- An epoxidation approach to a chiral lactone: Application of the Shi epoxidation
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The large-scale epoxidation of the alkene 7 with the organo-catalyst, Epoxone (10), and Oxone as the oxidant is described. This is the first large-scale application of the Shi epoxidation methodology. The large-scale preparation of the catalyst 10 is also described. The potassium salt of the unsaturated acid precursor 7 was prepared by a Suzuki coupling from 3-fluorobenzyl chloride and the vinylborane 8 derived from 4-pentynoic acid.
- Ager, David J.,Anderson, Ken,Oblinger, Eric,Shi, Yian,Vanderroest, James
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- Efficient catalysts for the asymmetric epoxidation of electron deficient as well as non electron deficient alkenes
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A compound of formula I and its enantiomeric counterpart V; a process for the preparation of diol I, and alternatively diol V, comprising a) the acetylation of diol II, or respectively diol VI, with an acetylating agent, wherein said acetylation is performed in the presence of a Lewis acid and b) an aqueous work-up of the reaction mixture; and a method for producing an enantiomerically enriched epoxide from an alkene, said method comprising admixing said alkene, a substantially enantiomerically pure chiral diol selected from the group comprising diol I and diol V and an oxidizing agent. The method can further comprise the addition of a phase-transfer catalyst.
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Page/Page column 5; 10
(2008/06/13)
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- 2-Azaadamantane N-oxyl (AZADO) and 1-Me-AZADO: Highly efficient organocatalysts for oxidation of alcohols
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Development of a stable nitroxyl radical class of catalysts, 2-azaadamantane N-oxyl (AZADO) and 1-Me-AZADO, for highly efficient oxidation of alcohols is described. AZADO and 1-Me-AZADO exhibit superior catalytic proficiency to TEMPO, converting various sterically hindered alcohols to the corresponding carbonyl compounds in excellent yields. Copyright
- Shibuya, Masatoshi,Tomizawa, Masaki,Suzuki, Iwao,Iwabuchi, Yoshiharu
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p. 8412 - 8413
(2007/10/03)
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- Practical synthesis of Shi's diester fructose derivative for catalytic asymmetric epoxidation of alkenes
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A practical synthesis of Shi's diester 3 for catalytic asymmetric epoxidations has been developed. The catalyst has been prepared in multigram quantities from D-fructose in four steps with a 66% overall yield. Efficiency, cost, and selectivity aspects of the reagents involved for its preparation have been taken care of during its preparation. The workup procedures have been simplified to the bare minimum, rendering a very practical preparation method. The well-known high efficiency of this catalyst 3 in the epoxidation of α,α-unsaturated carbonyl compounds has also proved to be high in unfunctionalized alkenes.
- Nieto,Molas,Benet-Buchholz,Vidal-Ferran
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p. 10143 - 10146
(2007/10/03)
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- Triazole linked carbohydrates
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Disclosed is an invention concerning triazolyloligosaccharides, oligosaccharides wherein the bonding between the saccharide groups is via a triazole group and methods for their preparation.
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Page column 7-8
(2008/06/13)
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- The Effect of pH Control on the Selective Ruthenium-Catalyzed Oxidation of Ethers and Alcohols with Sodium Hypochlorite
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Highly selective oxidations of ethers to esters or lactones and of secondary alcohols to ketones were achieved using catalytic amounts of various Ru precursors and the theoretical amount of NaOCl. Reactions were carried out in biphasic solvent mixtures at constant pH 9-9.5 via either feed-on-demand addition of HCl and NaOH or in the presence of NaHCO3/Na 2CO3 buffer. The catalyst could be easily recycled for at least 4 times with only minor loss in selectivity. Products were generally recovered by simple phase separation and evaporation of the organic solvent. The effects of catalyst precursor, additives and pH control method are also described.
- Gonsalvi, Luca,Arends, Isabel W. C. E.,Moilanen, Pasi,Sheldon, Roger A.
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p. 1321 - 1328
(2007/10/03)
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- Cyclic sugar ketones as catalysts for peroxygen compounds
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The use of cyclic sugar ketones of the formula in which R1and R2are hydrogen, C1-C22-alkyl, C2-C22-alkenyl or phenyl, R3is C1-C4-alkoxy, phenyl-CH2—O— or a group of the formula R4is hydrogen or R3and R4together are a group of the formula and n is zero or 1, as catalysts for peroxygen compounds.
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Page/Page column 12
(2008/06/13)
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- Catalytic asymmetric epoxidation
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A compound and method for producing an enantiomerically enriched epoxide from an olefin using a chiral ketone and an oxidizing agent is disclosed.
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Page column 25
(2010/01/30)
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- Selective ruthenium-catalyzed oxidation of 1,2:4,5-di-O-isopropylidene-β-D-fructopyranose and other alcohols with NaOCl
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Matrix presented The asymmetric epoxidation catalyst 1,2:4,5-di-O-isopropylidene-β-D-erythro-2,3-hexadiulo-2,6-pyranose 2 was obtained in high yield from 1,2:4,5-di-O-isopropylidene-β-D-fructopyranose 1 via a recyclable ruthenium-catalyzed hypochlorite oxidation protocol under biphasic conditions (MTBE/water) in the presence of an alkaline buffer (pH 9.5). Other secondary alcohols were also oxidized selectively to the correspondinq ketones.
- Gonsalvi, Luca,Arends, Isabel W. C. E.,Sheldon, Roger A.
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p. 1659 - 1661
(2007/10/03)
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- Structural modification of carbohydrates via functionalised organolithium intermediates: EPC preparation of branched-chain functionalised sugars
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The reductive opening of epoxides 1, 9, 13 derived from D-glucose and 18 derived from D-fructose using lithium and a catalytic amount of 4,4'-di-tert-butylbiphenyl (DTBB) in THF at -78°C allows the formation of β-oxido organolithium derivatives (2, 10, 14 and 19), which, by reaction with different electrophiles [H2O, D2O, Me3SiCl, PhCHO, Me2CO, Et2CO, (CH2)5CO, CO2] at the same temperature yields, after hydrolysis with water, the expected branched-chain functionalised carbohydrates. An alternative route for compound 11, derived from the epoxide 9, consists of the deprotonation of the chlorohydrin 12 followed by the same protocol of lithiation-reaction with an electrophile. The application of this methodology to the oxetane 4 allows compound 6 to be obtained through the corresponding γ-functionalised organolithium intermediates 5. Finally, the addition of the dianions 25 (resulting from the DTBB-catalysed lithiation of phthalan and isochroman) to the ketones 8 and 23, derived from D-glucose and D-fructose, respectively, allowed the stereoselective functionalisation at the 3-position of the sugars, giving the corresponding diols 26 and 27, which can cyclise to the corresponding heterocycles 28 and 29, respectively, under Mitsunobu reaction conditions. Copyright (C) 2000 Elsevier Science Ltd.
- Soler, Tatiana,Bachki, Abderrazak,Falvello, Larry R.,Foubelo, Francisco,Yus, Miguel
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p. 493 - 517
(2007/10/03)
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- Chemoselective Oxidation of Alcohols to Aldehydes and Ketones by tert -Butyl Hydroperoxide Catalyzed by a Ruthenium Complex of N,N′,N″-Trimethyl-1,4,7-triazacyclononane
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An operationally simple method based on [Cn*RuIII(CF3CO2) 3·H2O] (Cn* = N,N′,N″-trimethyl-1,4,7-triazacyclononane) catalyst and 1-1.2 equiv of tert-butyl hydroperoxide as terminal oxidant is effective for selective transformation of alcohols to aldehydes and ketones in methylene chloride. The reaction proceeds in high yield and selectivity. Preparation of benzaldehyde (98% yield) from benzyl alcohol on a 200 mmol scale can be performed without modification of the procedure such as slow addition of the oxidant or cooling to 0°C, and catalyst turnovers of 700 are achieved. Oxidation of geraniol which contains an isolated trisubstituted C=C bond leads to geranial selectively without oxidation of the C=C bond. Results from Hammett correlation studies (ρ = -0.47) and primary kinetic isotope effect (kH/kD = 4.8) for the catalytic benzyl alcohol oxidations are inconsistent with an oxoruthenium (O=Ru) based mechanism. A mechanism involving reactive tBuO·/tBuOO· radicals is also excluded based on results from previous works: Cheng, W.-C.; Fung, W.-H.; Che, C.-M. J. Mol. Catal. (A) 1996, 113, 311; absence of di-tert-butyl peroxide; and using cumyl hydroperoxide as a radical probe. A tert-butylperoxoruthenium complex is postulated to be the active intermediate.
- Fung, Wai-Hong,Yu, Wing-Yiu,Che, Chi-Ming
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p. 2873 - 2877
(2007/10/03)
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- An efficient catalytic asymmetric epoxidation method
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This article describes a highly effective catalytic asymmetric epoxidation method for olefins using,potassium peroxomonosulfate (Oxone, Dupont) as oxidant and a fructose-derived ketone(l) as catalyst. High enantioselectivies have been obtained-for trans-disubstituted and trisubstituted olefins which can bear functional groups such as tributylsilyl ether, acetal, chloride, and ester. The enantiomeric excesses cis-olefins and terminal olefins are not high yet. The current epoxidation shows that the catalyst efficiency is enhanced dramatically-upon raising the pH. Mechanitic studies show that the epoxidation mainly proceeds via a spiro transition state, which provides a model for predicting the stereochemical outcome of the reaction. The planar transition state, likely to be the main competing pathway. The extent of the involvement of the planar mode is subject to the steric of the alkyl groups on the olefins.
- Wang, Zhi-Xian,Tu, Yong,Frohn, Michael,Zhang, Jian-Rong,Shi, Yian
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p. 11224 - 11235
(2007/10/03)
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- Asymmetric Cyclopropanation Using New Chiral Auxiliaries Derived from D-Fructose
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Acetals of α,β-unsaturated aldehydes with 3-O-alkylated derivatives of 1,2-O-isopropylidene-β-D-fructopyranose and 1,2-O-isopropylidene-β-D-psicopyranose, which are readily available from D-fructose, were cyclopropanated with Et2Zn and CH2I2 with good diastereoselectivity.The effects of structure of the acetals on enantioselectivity were examined.
- Kang, Jahyo,Lim, Geun Jho,Yoon, Suk Kyoon,Kim, Moohi Yoo
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p. 564 - 577
(2007/10/02)
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- Synthetic studies on (+)-hydantocidin (3): A new synthetic method for construction of the spiro-hydantoin ring at the anomeric position of D-ribofuranose
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A facile synthetic route for the large-scale preparation of a herbicidal natural product, (+)-hydantocidin is described. The protected D-psicose 6, prepared in five steps from D-fructose, was stereospecifically converted to azido-amide 14 by N-glycosidation (TMSN3/TMSOTf), oxidation and animation. Hydantoin ring-construction on 14 was achieved by aza-Wittig reaction (PBu3/CO2/CH3CN) to give 16 without epimerization at the anomeric center. After acetylation, stepwise deprotection of 24 afforded (+)-hydantocidin 1 in 16% overall yield from D-fructose.
- Mio, Shigeru,Kumagawa, Yuko,Sugai, Soji
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p. 2133 - 2144
(2007/10/02)
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- Oxidation of partially protected carbohydrates at the nickel hydroxide electrode
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Primary hydroxy groups in pyranoses are oxidized in excellent yields to the corresponding carboxylic acids. In furanose 3 the yield of acid is only moderate. Secondary hydroxy groups are inert, aside from lactols. The different reactivity of secondary and primary hydroxy groups allows the chemoselective oxidation of 8 and 10.
- Schaefer, Hans J.,Schneider, Roy
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p. 715 - 724
(2007/10/02)
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- SYNTHESIS OF PHOSPHATE AND PHOSPHATES ISOSTERES OF FURANOSE SUGARS AS POTENTIAL ENZYME INHIBITORS
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Various D-furanose monosaccharides were synthesized as possible inhibitors of the gluconeogenic enzyme fructose 1,6-bisphosphatase.These included sulfamate, phosphoramidate, and epoxy analogues of the natural substrate, fructose 1,6-diphosphate (1), and arabinose and ribose analogues of a natural inhibitor, fructose 2,6-diphosphate (2).NMR studies were conducted to establish the stereochemistry of phosphate displacement at Cl in the synthesis of arabinose 1-phosphate derivatives. β-Ribose 1,5-diphosphate (35b) was prepared with >95 percent stereoselectivity.
- Maryanoff, Bruce E.,Reitz, Allen B.,Nortey, Samuel O.
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p. 3093 - 3106
(2007/10/02)
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- SYNTHESIS OF 3-SUBSTITUTED FURANS FROM 3-C-SUBSTITUTED HEXULOSES
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Addition of Grignard reagents to the hexodiulose obtained from oxidation of 1,2:4,5-di-O-isopropylidene-β-D-fructopyranose gave the corresponding 3-C-substituted hexuloses.A simple procedure for the direct conversion of these C-alkylated or -arylated hexu
- Fayet, Catherine,Gelas, Jacques
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- SYNTHESIS OF SOME DERIVATIVES OF 3-C-METHYL-D-PSICOSE, 3-C-METHYL-D-FRUCTOSE, AND 6-DEOXY-3-C-METHYL-D-PSICOSE
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The synthesis of di-O-isopropylidene derivatives of 3-C-methyl-D-psicose (3) and 3-C-methyl-D-fructose by the reaction of 1,2:4,5-di-O-isopropylidene-β-D-erythro-hexo-2,3-diulo-2,6-pyranose (2) with methylmagnesium iodide and methyllithium is described.The reaction of 2 with diazomethane and reduction of the resulting epoxides gave the same branched-chain sugars.Isomerisation of 3 and its transformation into the 6-deoxy-5-iodo derivative 9, followed by catalytic hydrogenation and hydrolysis of the isopropylidene groups, gave 6-deoxy-3-C-methyl-D-psicose.
- Cubero, Isidoro Izquierdo,Olea, Maria D. Portal
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