- 'Reductive Heck reaction' of 6-halopurines
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Alkenylation of 9-benzyl-6-halopurines with alkenes does not proceed under conventional Heck conditions. However, in the presence of triethylammonium formate a mixture of the corresponding saturated products was obtained. In contrast to the classical Heck reaction, the regioselectivity of this process is low giving a mixture of both α- and β-products regardless of the electronic nature of the substituent on the double bond of the alkene.
- Tobrman, Tomá?,Dvo?ák, Dalimil
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- Microwave promoted reaction of purin-6-yl magnesium halides with aldehydes in dichloromethane at 100u202f°C
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Treatment of a dichloromethane solution of 9-benzyl or 9-phenyl 6-iodopurine with ethereal ethylmagnesium bromide at ambient temperature gives the corresponding purin-6-yl magnesium halides. Addition of an aldehyde followed by heating at 100 °C in a microwave reactor yielded the corresponding carbinols in 52–81% yield.
- Gordon, Malcolm R.,Lindell, Stephen D.
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- The synthesis of nebularine and its analogs via oxidative desulfuration in aqueous nitric acid
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The synthesis of nebularine and its analogs has been achieved via oxidative desulfuration in H2O for the first time. With 50% HNO3as an oxidant and solvent, 18 products were obtained in good yields (70%–94%). The oxidative desulfuration system could tolerate different functional groups including fluoro, chloro, amino, alkyl, allyl, ribosyl, deoxyribosyl, and arabinofuranosyl groups.More importantly, the drug nebularine could be obtained successfully on a 20 g scale, which made this route more attractive for industrial applications.
- Xia, Ran,Sun, Li-Ping,Qu, Gui-Rong
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- Efficient synthesis of nebularine and vidarabine via dehydrazination of (hetero)aromatics catalyzed by CuSO4 in water
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A simple dehydrazination reaction has been achieved in the presence of a catalytic amount of CuSO4 for the first time. With CuSO4 (2 mol%) as a catalyst and water as a solvent, the dehydrazination products were obtained in good yields (66-95%). Moreover, the drugs nebularine and vidarabine were afforded successfully, and vidarabine could be produced on a 0.923 kg scale, which shows good potential for industrial applications.
- Xia, Ran,Xie, Ming-Sheng,Niu, Hong-Ying,Qu, Gui-Rong,Guo, Hai-Ming
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p. 1077 - 1081
(2014/03/21)
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- A method for the reductive scission of heterocyclic thioethers
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A mild, chemoselective, and generally high-yielding method for the reductive scission of heterocyclic thioethers is described. Suitable heterocycles have a thioether substituent at the 2-position relative to a ring heteroatom. The convenient and straightforward method is demonstrated with reactants which are not compatible with the standard Raney nickel conditions such as sulfides, sulfones, and thiophenes. In addition, benzyl esters, benzyl amides, and benzyl carbamates are tolerated by the reductive reaction conditions.
- Graham, Thomas H.,Liu, Wensheng,Shen, Dong-Ming
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supporting information; experimental part
p. 6232 - 6235
(2012/01/03)
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- Selective synthesis of 7-substituted purines via 7,8-dihydropurines
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A simple and efficient protocol for the preparation of 7-substituted purines is described. 6- and 2,6-Dihalopurines were N9-tritylated and then transformed to 7,8-dihydropurines by DIBAL-H. Subsequent N 7-alkylation followed by N9-trityl deprotection with trifluoroacetic acid was accompanied by spontaneous reoxidation, which led to the 7-substituted purines at 55 - 88% overall isolated yields.
- Kotek, Vladislav,Chudikova, Nadezda,Tobrman, Tomas,Dvorak, Dalimil
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p. 5724 - 5727
(2011/03/19)
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- DIKETO ACIDS WITH NUCLEOBASE SCAFFOLDS: ANTI-HIV REPLICATION INHIBITORS TARGETED AT HIV INTEGRASE IN COMBINATION THERAPY
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A new class of diketo acids constructed on nucleobase scaffolds, designed as inhibitors of HIV replication through inhibition of HIV integrase, is described. These compounds are useful in the prevention or treatment of infection by HFV and in the treatmen
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Page/Page column 64-65
(2008/06/13)
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- Diketo acids with nucleobase scaffolds: anti-HIV replication inhibitors targeted at HIV integrase
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A new class of diketo acids constructed on nucleobase scaffolds, designed as inhibitors of HIV replication through inhibition of HIV integrase, is described. These compounds are useful in the prevention or treatment of infection by HIV and in the treatmen
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Page/Page column 22
(2008/06/13)
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- Diketo acids on nucleobase scaffolds as inhibitors of Flaviviridae
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A new class of diketo acids constructed on nucleobase scaffolds, designed as inhibitors of HCV replication through inhibition of HCV NS5B RNA polymerase, is described. These compounds are useful in the prevention or treatment of infection by HCV and in th
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Page/Page column 22
(2010/11/24)
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- Nucleic acid related compounds. 136. Synthesis of 2-amino- and 2,6-diaminopurine derivatives via inverse-electron-demand Diels-Alder reactions
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Thermal inverse-electron-demand Diels-Alder reactions of 5-aminoimidazoles and 2,4,6-tris-(ethoxycarbonyl)-1,3,5-triazine (2) with spontaneous retro-Diels-Alder loss of ethyl cyanoformate and elimination of ammonia give 2,6-bis(ethoxycarbonyl)purines. A report that selective alkaline hydrolysis followed by acid-catalyzed decarboxylation gave 6-(ethoxycarbonyl)purine products was not in harmony with known reactions in purine chemistry. Our reinvestigation has shown that the 6-(ethoxycarbonyl) group undergoes preferential base-promoted hydrolysis, as expected, but regioselectivity for attack of hydroxide at the carbonyl group at C6 is not high (relative to hydrolysis of both C2 and C6 esters). The structure of 9-benzyl-2- (ethoxycarbonyl)purine was determined by X-ray crystallography and confirmed by Curtius rearrangement of the azidocarbonyl analogue to give 2-amino-6- benzylpurine. Acid-catalyzed decarboxylation of the 2,6-dicarboxylate formed during hydrolysis gave 9-benzylpurine, and Curtius rearrangement of 2,6-bis(azidocarbonyl)-9-benzylpurine gave 2,6-diamino-9-benzylpurine. Attempted applications of inverse-electron-demand Diels-Alder reactions of 2 with nucleoside derivatives were problematic.
- Lin, Xiaoyu,Robins, Morris J.
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p. 1029 - 1041
(2008/02/07)
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- 4-Metalated condensed pyrimidines: Their preparation and reaction with aldehydes under barbier-type conditions
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Equation presented. The organometallic intermediate obtained from halogen-metal exchanges of 4-iodo-6-phenylthieno[2,3-d]pyrimidine under Barbier-type conditions was reacted with aldehydes to form the corresponding alcohols in moderate yields. The reaction involving an organolithium intermediate proceeded only at low temperature, whereas the reaction involving a magnesium ate intermediate also proceeded at room temperature. A crystal structure confirms that the expected constitutional alcohol isomer is formed, where no migration has taken place. The conditions were also suitable for 9-benzyl-6-iodopurine.
- Therkelsen, Frans D.,Rottlaender, Mario,Thorup, Niels,Pedersen, Erik Bjerregaard
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p. 1991 - 1994
(2007/10/03)
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- Mitsunobu reactions for the synthesis of carbocyclic analogues of nucleosides: Examintion of the regioselectivity
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In order to provide a general synthetic method for carbocyclic nucleosides, regioselectivities in Mitsunobu reaction of purine, pyrimidin-2-one and their substituted derivatives with a variety of alcohols with a variety of alcohols were examined and found to depend upon both substituents of the bases and kind of the alcohols.
- Toyota,Katagiri,Kaneko
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p. 1295 - 1305
(2007/10/02)
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