- New photolabile protecting groups in nucleoside and nucleotide chemistry - Synthesis, cleavage mechanisms and applications
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New photolabile protecting groups have been found in the 2-(2- nitrophenyl)ethoxycarbonyl and the 2-(2-nitrophenyl)ethylsulfonyl group, respectively. The influence of substituents at the phenyl ring as well as the side-chain has been investigated regarding the photolysis rates on irradiation at 365 mn. β-Branching in the side-chain leads to highly increased rates of photodeprotection. A new type of photocleavage mechanism consisting of a photoinduced β-elimination process is proposed.
- Giegrich,Eisele-Buehler,Hermann,Kvasyuk,Charubala,Pfleiderer
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p. 1987 - 1996
(2007/10/03)
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- S-2-(2,4-dinitrophenyl)ethyl-L-cysteine: A new derivative for solid-phase peptide synthesis
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A new acid stable protecting group for the sulfhydryl function of cysteine is described. The S-2-(2,4-dinitrophenyl)ethyl-L-cysteine derivative is fully compatible with the Boc/Bzl solid-phase peptide synthesis strategy and can be smoothly and quantitatively removed to give the free thiol or a disulfide bridge.
- Royo,Garcia-Echeverria,Giralt,Eritja,Albericio
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p. 2391 - 2394
(2007/10/02)
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- Nucleotide. XIV. Substituierte β-Phenylaethyl-Gruppen. Neue Schutzgruppen fuer Oligonucleotid-Synthesen nach dem Phosphorsaeuretriester-Verfahren
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Various o- and p-substituted β-phenylethanols (2-10) have been synthesized and investigated as blocking groups in the phosphotriester approach.A large number of 5'-O-tritylated thymidine-3'-phosphotriesters (13-36) with two different phosphate protecting groups have been prepared, characterized, and studied according to their chemical stability and usefullness for oligonucleotide syntheses.The combination of a 5'-O-monomethoxytrityl- and a 3'-(2,5-dichlorophenyl, p-nitrophenylethyl)-phosphate function as in 18 turned out to possess optimal properties as a monomeric nucleotide building block due to the fact that these blocking groups can be quantitatively and selectively be removed without harming each other by trifluoroacetic acid in chloroform to 41, by oximate to 42, and by DBU to 43.The base-catalyzed removal of the monosubstituted phenylethyl groups by DBU or DBN respectively as well as the disubstituted phenylethyl groups by triethylamine in aprotic solvents is a β-elimination process leading to phosphodiesters without attack on the P-center.
- Uhlmann, Eugen,Pfleiderer, Wolfgang
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p. 1688 - 1703
(2007/10/02)
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