- Novel thermolabile protecting groups with higher stability at ambient temperature
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Novel thermolabile hydroxyl protecting groups of increased thermostability are proposed. The stability of these groups at different temperatures ranges has been determined. The 2-pyridyl-N-(2,4-difluorobenzyl)aminoethyl unit was selected as stable at ambient temperature and very labile at increased temperature. The half-life times for the best groups were established. Application of this chemistry to the protection of different hydroxyl groups of thymidine was also demonstrated.
- Chmielewski, Marcin K.
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p. 666 - 669
(2012/02/15)
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- Engineering N-(2-pyridyl)aminoethyl alcohols as potential precursors of thermolabile protecting groups
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Crystal and NMR analyses of four precursors of N-(2-pyridyl) thermolabile protecting group (TPG) were carried out. Two torsion angles have been identified as indicators that predict the molecules' thermolabile properties. Conformation that minimizes the N1...C8 distance is crucial for thermocyclisation. Nucleophilicity of the pyridyl ring is the driving force for the reaction but it is insufficient for thermocyclisation which is dominated by the molecules' ability to adopt a favourable conformation. The pKa value was recorded for all analyzed N-(2-pyridyl)aminoethyl alcohols. However, its effect is small in the determination of thermolability. Based on the analysis that we carried out, N-benzyl N-(2-pyridyl)aminoethyl was selected as a potential precursor of thermolabile carbonate of TPG. The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2012.
- Chmielewski, Marcin K.,Tykarska, Ewa,Markiewicz, Wojciech T.,Rypniewski, Wojciech
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experimental part
p. 603 - 612
(2012/05/04)
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- THERMOLABILE 2 - (N- 2 - PYRIDIYL - N- BENZYL) - AMINOETHYLOXYCARBONYL DERIVATIVES AS HYDROXYL FUNCTION PROTECTING AGENTS
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The subject of the invention is a new way of using thermolabile groups to protect a hydroxyl function, above all in nucleosides, nucleotides, oligomers, nucleic acids during the reactions of organic synthesis. The invention also covers new compounds that
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Page/Page column 10
(2012/01/05)
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- Ruthenium-catalyzed /V-alkylation of amines and sulfonamides using borrowing hydrogen methodology
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The alkylation of amines by alcohols has been achieved using 0.5 mol percent [Ru(p-cymene)CI2]2 with the bidentate phosphines dppf or DPEphos as the catalyst. Primary amines have been converted into secondary amines, and secondary amines into tertiary amines, including the syntheses of Piribedil, Tripelennamine, and Chlorpheniramine. A/-Heterocyclization reactions of primary amines are reported, as well as alkylation reactions of primary sulfonamides. Secondary alcohols requiremore forcing conditions than primary alcohols but are still effective a lkylating agents in the presence of this catalyst.
- Hamid, M. Haniti S. A.,Allen, C. Liana,Lamb, Gareth W.,Maxwell, Aoife C.,Maytum, Hannah C.,et al.
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supporting information; experimental part
p. 1766 - 1774
(2009/07/25)
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