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1.
Polymer-supported reagents for organic synthesis are enjoying a renewed popularity with the emergence of combinatorial chemistry in recent years1. 4-(Arylseleno)morpholines formed in situ are useful -seleno-introducing reagents for saturated aldehydes2. -Sele- noaldehydes, as a frequently used intermediates, can be converted into -haloaldehydes by halogenating reaction3. However, organic selenium reagents always have a foul smell and are quite toxic, which is often problematic in organic sy… 相似文献
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Yang Geng Maolin Zheng Jingya Li Dapeng Zou Yusheng Wu Yangjie Wu 《Tetrahedron letters》2017,58(42):3966-3969
A concise synthesis of (S)-3-hydroxytetrahydropyran from natural l-glutamic acid has been developed. The intramolecular etherification starting from 1,5-diol was promoted by trifluoromethanesulfonic anhydride. The clinnamates of the alcohols were prepared for accurately determining the optical purity by HPLC method. 相似文献
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Harding WW Hodge M Wang Z Woolverton WL Parrish D Deschamps JR Prisinzano TE 《Tetrahedron: Asymmetry》2005,16(13):2249-2256
The enantioselective synthesis of the (R,R)- and (S,S)-enantiomers of 1 from commercially available 3-chlorocinnamic acid is reported. The Sharpless asymmetric epoxidation was used to establish the stereocenters in the synthesis of both enantiomers of 1. 相似文献
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(S,S)-Reboxetine was synthesized stereospecifically in 30% overall yield and 99% ee in eight steps. Key steps were selective oxidation of an N-protected hydroxymethylmorpholine and aryl-chromium-mediated aromatic nucleophilic substitution. [structure: see text] 相似文献
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The fluorinated amino acid, (2S,3S)-3'-fluoroisoleucine 3, has been synthesised by a route involving stereoselective cuprate or photochemical addition to the compound 4, derived in turn from (2S)-pyroglutamic acid. This provides a reporter group for the hydrophobic amino acid (2S)-isoleucine for use in protein studies. 相似文献
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Gard Gjessing Lars-Inge Gammelster Johnsen Simen Gjelseth Antonsen Jens M. J. Nolse Yngve Stenstrm Trond Vidar Hansen 《Molecules (Basel, Switzerland)》2022,27(7)
Monohydroxylated polyunsaturated fatty acids belonging to the oxylipin class of natural products are present in marine and terrestrial sources as well as in the human body. Due to their biological activities and role in diverse biosynthetic pathways, oxylipins biosynthesized from eicosapentaenoic acid and arachidonic acid have attracted great interest from the scientific community. One example is 3-hydroxyeicosapentaenoic acid where the absolute configuration at C-3 has only been tentatively assigned. In this paper, studies on acetate type aldol reactions that enabled the preparation of 3-(R)-hydroxyeicosapentaenoic acid (3R-HETE, 2) and its enantiomer are presented. 相似文献
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Nikolina Berova Stefan Eojadziev Nevenka Bresciani-Pahor Petko M. Ivanova Biserka Koji-Prodic Rositza Rakovska
Iva Rui-Toro Günther Snatzke 《Helvetica chimica acta》1990,73(7):1853-1860
The absolute configuration of the 2-(phenylmethyl)pyridine derivatives 1 – 9 had been established by X-ray diffraction and chemical correlation. Their CD spectra have been studied in different solvents for the free and protonated forms. It has now been found that, from the sign of the strong CD couplet between 270 and 220 nm, which was observable for all these compounds besides 7 and 9 , their absolute configuration can be determined much quicker. 相似文献
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(+)-(S)-Streptenol A is synthesized by coupling a 1,3-dithiane with an optically pure epoxide. The absolute configuration of (+)-(S)-streptenol A is thereby correlated with that of (S)-malic acid. Stereoselective reduction of an oxime that could easily be prepared from streptenol A gave the (3S,5R)- and (3S,5S)-aminostreptenols, and after cyclization, configurationally pure 2,4-functionalized piperidine alkaloids. 相似文献
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苄氧乙基环氧乙烷;不对称合成;由(S)-和( R )-天冬氨酸合成( R )-和(S)-(2-苄氧乙基)环氧乙烷的改良方法 相似文献
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Optically active (+)-(S)-5-sec-butyl- and (-)-(S)-3-sec-butyl-2(1H)-pyridinone are synthesized and the relationship between optical activity and minimum optical purity of the latter is determined. 相似文献
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A stereospecific requirement for hallucinogenesis applies to certain molecules containing an asymmetric center. Thus, only the R-isomers of substituted phenylisopropylamines and lysergic acid diethylamide are psychotomimetic. The enantiomers of a minor hallucinogen, S(+)- and R(-)-3-(2-aminopropyl)indole (α-methyltryptamine) ( 6a and 6b ) were synthesized via a 5-step manipulation from D - and L -tryptophan ethyl ester hydrochloride, respectively. Optical purity of these two isomers was determined by pmr spectroscopy of their complexes with a europium chiral shift reagent using the indole C2 H signal. 相似文献
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Xavier Verdaguer Iolanda Marchueta Jordi Tormo Albert Moyano Miquel A. Perics Antoni Riera 《Helvetica chimica acta》1998,81(1):78-84
A convenient preparation of (1R,2S,3R,4S)-3-(neopentyloxy)isoborneol (= (1R,2S,3R,4S)-3-(2,2-dimethyl-propoxy)-1,7,7-trimethylbicyclo[2.2.1]heptan-2-ol; 1a ), a valuable chiral auxiliary, is described. The synthesis involves six steps starting from the readily available camphorquinone ( 5 ) and gives 1a in 48% overall yield. The key step is the chemoselective hydrolysis of the less hindered 1,3-dioxolane moiety in the camphorquinone di-acetal 4 . 相似文献
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Conclusions A seven-stage synthesis has given optically active (2R/S, 3S, 7R/S)-2-acetoxy-3,7-dimethylpentadecane from the readily available (S)-(+)-3,7-dimethyl-1,6-octadiene, in an overall yield of 36%. The synthetic route utilizes all ten carbon atoms of the starting chiral diene.For previous communication, see [1].Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1142–1146, May, 1988. 相似文献
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E-(R)-5-Hydroxy-2-hexenoic acid (4) and the acetonide of E-(4R,5R,7R)-trihydroxy-2-octenoic acid (3) are joined to give, after deprotection, (+)-colletodiol (1). The syntheses of the two hydroxy-acids from poly-(R)-3-hydroxy-butanoate (PHB) and (?)-tartaric acid, respectively, are outlined. 相似文献
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M. Carmen Carre o Jos L. Garcí a Ruano Miguel A. Toledo Antonio Urbano 《Tetrahedron letters》1994,35(52):9759-9762
The synthesis of the title compounds in enantiomerically pure form is described. Their cycloadditions with cyclopentadiene and 2,3-dimethyl-1,3-butadiene in the presence of ZnBr2 take place on the unsubstituted dienophilic double bond C5-C6 giving access to optically active 4a,5,8,8a-tetrahydronaphthoquinones with a diastereoisomeric excess ranging from 40 to 72%. 相似文献