- Synthesis of 2'-deoxy-4'-C-hydroxymethyl-4'-thioribonucleosides and their 2',3'-dideoxy and 2',3'didehydro-2',3'-dideoxy analogues
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(±)-2'-Deoxy-4'-C-hydroxymethyl-4'-thioribonucleosides (1) and their 2',3'-dideoxy- (2) and 2',3'-didehydro-2',3'-dideoxy- (3) analogues have been prepared from hydrothiophene derivatives 2,2-bis(benzyloxymethyl)-3-benzyloxytetrahydrothiophene (4), 2,2-bis-(acetoxymethyl)tetrahydrothiophene (5) and 2,2-bis(acetoxymethyl)-2,5-dihydrothiophene (6), respectively. Preparation of the compound 1 has been carried out via N-glycosylation of the corresponding sulfoxide 9, derived from 4 by m-CPBA oxidation, with trimethylsilylated pyrimidines and trimethylsilyl triflate (Kita-O'Niel-Matsuda's method; modified Pummerer rearrangement). On the other hand, the compounds 2 and 3 have been obtained via N-glycosylation of the corresponding 4'-thiofuranoses 7 and 8 with trimethylsilylated pyrimidines and SnCl4, respectively, while the compounds 7 and 8 have been prepared from compounds 5 and 6 by an electrochemical 2-acetoxylation, respectively.
- Nokami, Junzo,Mae, Masayuki,Fukutake, Satoshi,Ubuka, Tomoyuki,Yamada, Mitsuhiro
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p. 1337 - 1360
(2009/07/05)
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- Halogenation of carbonyl compounds by an ionic liquid, [AcMIm]X, and Ceric Ammonium Nitrate (CAN)
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An ionic liquid, acetylmethylimidazolium halide ([AcMIm]X), in combination with ceric ammonium nitrate promotes halogenations of a wide variety of ketones and 1,3-keto esters at the ?-position. The ionic liquid acts here as reagent as well as reaction medium, and thus the reaction does not require any organic solvent or conventional halogenating agent. The reaction is completely arrested when the radical quencher TEMPO is used. A plausible radical mechanism is also suggested. CSIRO 2007.
- Ranu, Brindaban C.,Adak, Laksmikanta,Banerjee, Subhash
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p. 358 - 362
(2008/02/13)
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- APPLICATIONS OF THE ENE REACTION. SYNTHESIS AND PROPPERTIES OF SUBSTITUTED &α-METHYLENE-&γ-LACTONES
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Substituted dimethyl 1,4-pentadiene-1,2-dicarboxylates ( 1 or 3 ) may be prepared by AlCl3-promoted or thermal ene reaction of olefins with dimethyl acetylenedicarboxylate.Lactonization of these adducts is catalyzed by acid.In the presence of 80 percent H2SO4 the predominant product ( ca. 80 percent ) is a (Z)-dihydro-3-carbomethoxymethylene-2(3H)-furanone ( 2 or 4 ).Cyclization with anhydrous HCl affords a mixture of products the composition of which depends on the starting material; major products include the corresponding (E)- and γ-lactone isomers ( 6 and 7 ).Detailed 1H and 13C nmr are reported for all compounds.The structures of the (E)-4,5,5-trimethyl-, (Z)-4,5,5-trimethyl-, and (Z)-4,4,5,5-tetramethyl furanone derivatives ( 6a, 2a, and, 2b,) have been established by X-ray crystallography.The properties of some of these lactones are discussed, as are possible methods of removal of the carbomethoxyl from 2.
- Hanson, Alfred W.,McCulloch, Archibald W.,McInnes, A. Gavin
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p. 288 - 301
(2007/10/02)
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