- Efficient synthesis of α-branched purine-based acyclic nucleosides: Scopes and limitations of the method
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An efficient route to acylated acyclic nucleosides containing a branched hemiaminal ether moiety is reported via three-component alkylation of N-heterocycle (purine nucleobase) with acetal (cyclic or acyclic, variously branched) and anhydride (preferentially acetic anhydride). The procedure employs cheap and easily available acetals, acetic anhydride, and trimethylsilyl trifluoromethanesulfonate (TMSOTf). The multi-component reaction is carried out in acetonitrile at room temperature for 15 min and provides moderate to high yields (up to 88%) of diverse acyclonucleosides branched at the aliphatic side chain. The procedure exhibits a broad substrate scope of N-heterocycles and acetals, and, in the case of purine derivatives, also excellent regioselectivity, giving almost exclusively N-9 isomers.
- Dra?ínsky, Martin,Frydrych, Jan,Janeba, Zlatko,Slavětínská, Lenka Po?tová
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- Product study of the OH radical and Cl atom initiated oxidation of 1,3-dioxane
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The products of the hydroxyl (OH) radical and chlorine (Cl) atom initiated oxidation of 1,3-dioxane are determined under various reaction conditions in a 50 L teflon reaction chamber using FTIR spectroscopy for analysis. The major products detected in all experiments are (2-oxoethoxy)methyl formate, formic acid and methylene glycol diformate with average molar yields of 0.50±0.05, 0.41±0.02 and 0.03±0.01 respectively for the OH initiated oxidation in the presence of NOx. The yields of these products do not vary significantly with O2 partial pressure or oxidising agent (OH or Cl). However, the yield of formic acid decreased by at least a factor of two in the absence of NOx. The results of these experiments are used to elucidate a simplified gas-phase atmospheric degradation scheme for 1,3-dioxane and also provide valuable information on the atmospheric fate of the cyclic and linear alkoxy radicals produced in these and similar reactions. The available experimental data suggests that the relative importance of the competing pathways (reaction with O2 and ring opening by C-C or C-O bond fission) is a strong function of the ring strain in the cycloalkoxy radicals.
- Moriarty, Jennie,Wenger, John C.,Sidebottom, Howard W.
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experimental part
p. 3980 - 3986
(2011/10/02)
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- Solid-liquid phase transfer catalysis III: synthesis of azido acyclic nucleosides of pyrimidine
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A series of novel azido acyclic nucleosides of pyrimidine derivatives were prepared using solid-liquid phase transfer catalysis (S.L.P.T.C) and tested as anti-HIV agents in cell assay.
- Lazrek, Hassan B.,Taourirte, Moha,Barascut, Jean-L.,Imbach, Jean-L.
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- 4-Substituted dioxolanes by chemoselective reactions on glycerol formal
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4-Hydroxymethyl-1,3-dioxolane contained in glycerol formal undergoes chemoselective transformations, which constitute a direct entry to 4-substituted-1,3-dioxolanes.
- Gras,Dulphy,Marot,Rollin
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p. 4335 - 4336
(2007/10/02)
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- ASYMMETRIC SYNTHESIS OF D-erythro-SPHINGOSINE
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D-erythro-Sphingosine 9 is a building block of cerebrosides and glycosphingolipids and was synthesized in 5 steps via an asymmetric aldol addition of the lithiated bislactim ether of cyclo-(L-Val-Gly) 4 to (2E)-hexadecenal (3) in an overall yield of 21percent.
- Groth, Ulrich,Schoellkopf, Ulrich,Tiller, Thomas
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p. 2835 - 2842
(2007/10/02)
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- RIBONUCLEOSIDES OF 3-AMINO- AND 3,5-DIAMINOPYRAZOLE-4-CARBOXYLIC ACID AND THEIR OPEN-CHAIR ANALOGUES: SYNTHESIS AND REACTIONS
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Bis(trimethylsilyl) derivative of ethyl 3-aminopyrazole-4-carboxylate (VI) and tris(trimethylsilyl) derivative of ethyl 3,5-diaminopyrazole-4-carboxylate (VII) on reaction with 2,3,5-tri-O-benzoyl-D-ribofuranosyl chloride and subsequent debenzoylation afforded the respective β-D-ribofuranosyl derivatives VIIIa and Xa.Their alkaline hydrolysis led to 1-(β-D-ribofuranosyl)-3-aminopyrazole-4-carboxylic acid (VIIIc) and 1-(β-D-ribofuranosyl)-3,5-diaminopyrazole-4-carboxylic acid (Xb).The esters VIIIa and Xa were not ammonolysed under normal conditions.Contrary to nucleosidation of the silyl derivatives VI and VII, sodium salt of ethyl 3-aminopyrazole-4-carboxylate was alkylated with 4-chloromethyl-2,2-dimethyl-1,3-dioxolane (XI) or 5-(p-toluenesulfonyloxy)-1,3-dioxane (XVIIb) to give a mixture of the N-isomeric derivatives XIIIa, XIXa and XIIa, XVIIIa, respectively; sodium salt of the 3,5-diamino derivative V reacted with these synthons under formation of the corresponding compounds XIIIb and XXa.Subsequent alkaline and acid hydrolysis of XIIa and XIIIb gave the open-chain analogs of nucleosides XV and XVI.The N-(1,3-dioxan-5-yl) derivatives XVIIIc and XXc resisted acid hydrolysis, giving rise only to carboxylic acids XVIIIb and XXb.
- Spassova, Maria K.,Holy, Antonin,Masojidkova, Milena
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p. 1512 - 1531
(2007/10/02)
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- 2-dioxacycloalkylthiopenem derivatives
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Certain 2-dioxacycloalkylthio-2-penem-3-carboxylic acid compounds are useful as antibacterials for treating mammals and have the formula STR1 or a pharmaceutically acceptable salt thereof, wherein: R is STR2 A is carbonyl, methylene or thiocarbonyl; B is
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