共查询到20条相似文献,搜索用时 15 毫秒
1.
We developed a new protecting group, ie., cis-[4-[[(4-methoxytrityl)sulfenyl]oxy]tetrahydrofuran-3-yl]oxycarbonyl (MTFOC), which could be removed under neutral conditions involving the oxidative removal of the MMTrS group followed by the self-cyclization of the resulting intermediate. The introduction of the protecting group into the 5-hydroxyl group of a thymidine derivative and its deprotection were studied. 相似文献
2.
《Nucleosides, nucleotides & nucleic acids》2013,32(5-7):927-929
We developed a new protecting group, i.e., cis-[4-[[(4-methoxytrityl)sulfenyl]oxy]tetrahydrofuran-3-yl]oxycarbonyl (MTFOC), which could be removed under neutral conditions involving the oxidative removal of the MMTrS group followed by the self-cyclization of the resulting intermediate. The introduction of the protecting group into the 5′-hydroxyl group of a thymidine derivative and its deprotection were studied. 相似文献
3.
Allyl protection of O6 position of 2'-deoxyguanosine 总被引:1,自引:0,他引:1
Allyl serves as the protecting group for O6 position of guanosine. The deblocking is easily performed by brief treatment with a palladium(O) catalyst and a nucleophile. 相似文献
4.
Sankha Pattanayak Sibasish Paul Bappaditya Nandi Surajit Sinha 《Nucleosides, nucleotides & nucleic acids》2013,32(11):763-782
An inexpensive and much improved protocol has been developed for the synthesis of protected morpholino monomers from unprotected ribonucleosides in high overall yield, using oxidative glycol cleavage and reductive amination strategy. Unlike the previous methods, the present strategy allows installing the exocyclic amine protections at a later stage, and thus avoids the use of expensive, or commercially unavailable, exocyclic amine-protected ribonucleosides as starting materials. To demonstrate the flexibility of the present method in choosing protecting groups, the monomers have been protected with several such groups of different deblocking properties at the exocyclic amine position. 相似文献
5.
Removal of some commonly used protecting groups in peptide synthesis by catalytic transfer hydrogenation employing hydrazinium monoformate and 10%Pd on carbon is described. This method is equally competitive with other methods in deblocking most of the commonly used protecting groups in peptide synthesis. tert-Butyl derived and base labile protecting groups were completely stable under these conditions. This is more effective than hydrazine or formic acid. 相似文献
6.
J Blake D Yamashiro K Ramasharma C H Li 《International journal of peptide and protein research》1986,28(5):468-476
The amino acid residue peptide, alpha-inhibin-92 (alpha-IB-92), has been synthesized by the thiocarboxyl segment strategy. Three segments were synthesized by the solid phase method, purified, and characterized: [GlyS34]-alpha-IB-92-(1-34) (I), CF3CO-[GlyS65]-alpha-IB-92-(35-65) (II), and Msc-alpha-IB-92-(66-92) (III). All were reacted with citraconic anhydride followed by removal of the Msc group in III to give Ia, IIa, and IIIa, respectively. Peptide IIIa was coupled to IIa by the silver nitrate/N-hydroxysuccinimide procedure and, after removal of uncoupled segments and the trifluoroacetyl group, Ia was coupled followed again by removal of uncoupled segments. Final deblocking to remove citraconyl groups was accomplished under exceptionally mild conditions in aqueous acetic acid. The synthetic product was identical to natural alpha-IB-92 in amino acid analysis, HPLC, gel electrophoresis, and tryptic mapping. The synthetic peptide was indistinguishable from natural alpha-IB-92 in a radioimmunoassay and in an in vitro mouse pituitary assay for measuring suppression of FSH release in the presence of LHRH. 相似文献
7.
During the incorporation of 8-amino-dG into oligomeric DNA, the deprotection conditions previously recommended (28% ammonia at room temperature) do not effect complete removal of the dimethylaminomethylene protecting groups. At elevated temperatures oxidative degradation of the oligomer and exchange of ammonia with dimethylamine in the protecting group at C8 occurred. The resolution of these problems and a method to obtain a series of homogeneous oligomers in reasonable yield containing 8-amino-dG located site-specifically are described. 相似文献
8.
G. M. Visser R. Keemink Cecile Schattenkerk B. Kraal J. H. Van Boom 《Nucleosides, nucleotides & nucleic acids》2013,32(3):277-286
Abstract Phosphorylation of 2′-0-acetyl-3′-trifluoroacetamido-3′-deoxy-N2-palmitoylguanosine with N-morpholino-O, O-bis(1-benzotriazolyl)phos-phate gives a 5′-phosphotriester. Removal of the benzotriazolyl group and addition of pyrophosphoric acid gave, after deblocking all protecting groups, GTP(3′NH2). 相似文献
9.
Bile acid derivatives, with and without C-3 sulfate groups, and having either the diazo- or halomethylketone moieties, have been synthesized in good yield and purity. The synthetic sequence, COOH leads to COC1 leads to COCHN2 leads to COCH2X, was used with deoxycholic and cholic acids, which requires carefully controlled quench, work-up, and purification procedures, especially for the 3-sulfate esters (made from deoxycholic acid derivatives only). The pure title compounds are anticipated to be useful chemical probes (affinity labels), especially the completely water soluble sulfates, toward our studies of ileal active transport of bile salts. A new use for Sephadex LH-20 as a sulfate ester protecting group is reported. Also developed were the use of acetamide hydrochloride complex as a mild hydrochlorination reagent and a neutral desalting method for sulfate esters of deoxycholic acid derivatives. 相似文献
10.
Suode Zhang Feng Lin Mohammed Akhter Hossain Fazel Shabanpoor Geoffrey W. Tregear John D. Wade 《International journal of peptide research and therapeutics》2008,14(4):301-305
The S-acetamidomethyl (Acm) protecting group is widely used in the chemical synthesis of peptides that contain one or more
disulfide bonds. Treatment of peptides containing S-Acm protecting group with iodine results in simultaneous removal of the
sulfhydryl protecting group and disulfide formation. However, the excess iodine needs to be quenched or adsorbed as quickly
as possible after completion of the disulfide bond formation in order to minimize side reactions that are often associated
with the iodination step. We report a simple method for simultaneous post-cysteine (Acm) group removal quenching of iodination
and isolation. Use of large volumes of diethyl ether for direct precipitation action of the oxidized peptide from the 90 or
95% aqueous acetic acid solution affords nearly quantitative recovery of largely iodine-free peptide ready for direct purification.
It was successfully applied to the synthesis of various peptides including human insulin-like peptide 3 analogues. Although
recovery yields were comparable to the traditionally used ascorbic acid quenching method, this new approach offers significant
advantages such as more simple utility, minimal side reactions, and greater cost effectiveness. 相似文献
11.
Gowda D. Channe Abiraj K. Augustine Paul 《International journal of peptide research and therapeutics》2002,9(1):43-47
Summary Removal of some commonly used protecting groups in peptide synthesis by catalytic transfer hydrogenation employing ammonium
formate and magnesium is described. This method is equally competitive with other methods in deblocking most of the commonly
used protecting groups in peptide synthesis.tert-Butyl derived and base labile protecting groups were completely stable under these conditions. The use of ammonium formate
and magnesium makes this a rapid, low-cost alternative to palladium and reduces the work-up to a simple filtration and extraction
operation. 相似文献
12.
Removal of some commonly used protecting groups in peptide synthesis by catalytic transfer hydrogenation employing ammonium formate and magnesium is described. This method is equally competitive with other methods in deblocking most of the commonly used protecting groups in peptide synthesis. tert-Butyl derived and base labile protecting groups were completely stable under these conditions. The use of ammonium formate and magnesium makes this a rapid, low-cost alternative to palladium and reduces the work-up to a simple filtration and extraction operation. 相似文献
13.
Preparation of covalently linked DNA-RNA hybrids and arabinocytidine containing DNA fragments. 总被引:1,自引:1,他引:0
下载免费PDF全文
![点击此处可从《Nucleic acids research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
E de Vroom H C Roelen C P Saris T N Budding G A van der Marel J H van Boom 《Nucleic acids research》1988,16(7):2987-3003
It will be demonstrated that 5'-O-DMT-N-acyl-deoxyribonucleosides, 5'-O-Lev-2'-O-MTHP-N-acyl-ribonucleosides and, also, 2'-O-MTHP-N-acyl-ara-cytidine can be coupled, via the hydroxybenzotriazole phosphotriester approach, to afford two types of DNA-RNA hybrids as well as ara-C containing DNA-fragments. The final removal of acid-labile DMT and MTHP groups could be effected by 1 h treatment with 80% acetic acid of the otherwise unprotected DNA-RNA hybrids. The same acidic hydrolysis did not result in complete removal of the 2'-O-MTHP group from the ara-C unit. Complete deblocking was accomplished after an additional 2 h aqueous HC1 (0.01 M; pH 2.00) treatment. 相似文献
14.
The synthesis of gracillin and dioscin: two typical representatives of spirostanol glycosides 总被引:1,自引:0,他引:1
Two representative spirostanol saponins that have the typical structure for the sugar moiety, diosgenyl alpha-L-rhamnopyranosyl-(1-->2)-[beta-D-glucopyranosyl-(1-->3)]-beta-D-glucopyranoside (gracillin) and diosgenyl alpha-L-rhamnopyranosyl-(1-->2)-[alpha-L-rhamnopyranosyl-(1-->4)]-beta-D-glucopyranoside (dioscin), were easily synthesized by a general approach. A procedure using guanidine for the selective deblocking of acetyl while retaining benzoyl protecting groups is described. 相似文献
15.
We have developed a new type of 2'-hydroxyl protecting group for the automated machine synthesis of RNA oligomers: a 2-hydroxyisophthalate formaldehyde acetal (HIFA). The unique feature of this protecting group is that, as the bis ester, it is relatively stable to the acidic conditions that are used for repeated removal of dimethoxytrityl groups during chain elongation, but the final deprotection step in alkali, which cleaves the chain from the support and removes the base and phosphate protecting groups, converts it to the bis carboxylate and this can be removed relatively rapidly by treatment with mild acid. Conversion of the bis ester to the bis carboxylic acid increases the rate of acid-catalyzed hydrolysis of the acetal by 42-fold at pH 1, and, possibly, by 1320-fold at pH 3. The bis ester is 112 times more stable than the 1-(2-fluorophenyl)-4-methoxypiperidin-4-yl group (Fpmp) towards hydrolysis at pH 1, while the bis acid is only 2.35 times more stable than Fpmp at pH 3. In synthesis of the dimers UpU and UpG, with a coupling time of 5 min, the dimethoxytrityl cation assay indicated coupling yields of > 98%. 相似文献
16.
Hellström JL Vehniäinen M Mustonen M Lövgren T Lamminmäki U Hellman J 《Biochimica et biophysica acta》2006,1764(11):1735-1740
To enable Edman sequencing of pyroglutamylated immunoglobulins, enzymatic deblocking by pyroglutamate aminopeptidase is performed, often with variable yield and compromised solubility. Recently, enzymatic deblocking of immunoglobulins without denaturation was described. Although the conditions ensured efficient removal of pyroglutamyl residues, we conclude that deblocking is preceded by denaturation, which results in aggregation of the immunoglobulins. To study the effect of folding status on deblocking we developed a methanol based deblocking solution, which preserved the enzymatic activity of pyroglutamate aminopeptidase, provided conditions compatible with sequencing and enhanced deblocking of electroblotted samples, as well. At 50 degrees C and 35% (v/v) methanol the immunoglobulin chains were completely aggregated, but the degree of deblocking was comparable to that obtained with the previously described method. At 37 degrees C, the immunoglobulins were partly aggregated, but the deblocked chains were completely in the insoluble fractions, whereas the soluble fractions had retained pyroglutamylation in both chains, suggesting that unfolding of the immunoglobulins is required for the excision of the pyroglutamates. Inspection of the structures of pyroglutamylated immunoglobulin and pyroglutamate aminopeptidase P. furiosus indicates that the enzyme requires the substrate in an extended conformation, a criterium, which we conclude not to be fulfilled in the native form of immunoglobulins. Unfolding of the N-terminus would disrupt the immunoglobulin fold by breaking interactions between secondary structure elements and expose surfaces prone to aggregation. 相似文献
17.
2-(2-Pyridyl)ethyl group is a new type P-O protecting group for the synthesis of oligodeoxyribonucleotides by the phosphite triester method. This group is stable to alkali and acid conditions, and to be removed from internucleotidic bonds under mild conditions via two step procedures without any side reactions. Further we have found that bis(diisopropylamino)chlorophosphine is much more effective for the preparation of bis(diisopropylamino)alkoxyphosphines than various dichlorophosphines. 相似文献
18.
Isabelle Rasolonjatovo Simon R. Sarfati 《Nucleosides, nucleotides & nucleic acids》2013,32(9-11):2021-2025
Abstract 6-Amino-4-oxo-hexanoic acid with a fluorescent probe attached to the amino function, derivative of the levulinic acid has been developed for protection of hydroxyl groups. It is introduced by reaction of its symetrical anhydride and rapidly removed under mild conditions using a hydrazine-pyridinium acetate buffer at near neutral pH and room temperature. It can be used within the scope of a new DNA sequencing method and as a sensitive detectable protecting group. 相似文献
19.
Suode Zhang Per I. Arvidsson 《International journal of peptide research and therapeutics》2008,14(3):219-222
A highly efficient and safe methodology for synthesis of various N-protected amino acid ethyl esters have been established in this study. This methodology employs orthoesters as both esterification
reagent and solvent for protected amino acids. The reactions were carried out under microwave irradiation in neutral conditions
for only 2 min, resulting in highly pure crude products in most cases. This strategy works with a variety of N-protecting groups, such as acid labile protecting group: BOC and tBu; base labile protecting group: Fmoc; hydrogenation labile
protecting group: Z and Na/NH3 labile protecting group: Tos, thus providing facile access to numerous valuable building blocks for solid phase synthesis.
Further reduction of the crude protected amino acid ethyl ester by sodium borohydride under mild conditions led to the corresponding
protected β-amino alcohols with excellent yield, as demonstrated by three examples. 相似文献
20.
Prevention of chain cleavage in the chemical synthesis of 2''-silylated oligoribonucleotides. 总被引:17,自引:14,他引:3
下载免费PDF全文
![点击此处可从《Nucleic acids research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Strong aqueous ammonium hydroxide used to remove N-acyl protecting groups from synthetic oligoribonucleotides causes removal of some alkylsilyl protecting groups from 2'-hydroxyls and leads to chain cleavage. This problem is most severe when 30% ammonium hydroxide is used and substantially reduced but still detectable when 3:1 ammonium hydroxide-ethanol is used. We have virtually eliminated this unwanted cleavage by incorporating the labile phenoxyacetyl amino protecting group on adenosine and guanosine. The N-benzoyl protecting group remains adequate for cytidine nucleosides. Synthetic oligoribonucleotides containing these N-acylated nucleosides and 2'-t-butyldimethylsilyl or 2'-triisopropylsilyl protecting groups can be deacylated by room temperature treatment in saturated anhydrous methanolic ammonia (8-12 h) without causing any detectable chain cleavage. 相似文献