Solid phase synthesis of nonadecathymidylic acid by the phosphotriester approach

Nonadecathymidylic acid was synthesized by the block coupling phosphotriester approach on a polymer support.     

Synthesis and antitumor activity of inositol phosphotriester analogues

Inositol phosphates, as important second messengers of signal transduction, regulate many biological functions. However, cell penetration and phospholipase stability could be two main issues faced by inositol phosphate analogues used as lead compounds for drug discovery. Inositol phosphotriester analogues could be more beneficial to diffuse across plasma membrane. In this paper, we describe the design and synthesis of a series of inositol phosphotriester analogues based on phosphatidylinositol, along with the initial antitumor activity analysis. Several compounds exhibited good cytotoxic activity against human cancer cell lines A549, HepG2, MDA-MB-231 and HeLa, especially compound 33 was cytotoxic against all the four cancer cell lines with good IC(50) values.     

Atropisomerism of diastereomer diribonucleoside phosphotriester

Linear diribonucleoside phosphotriester is an important intermediate for synthesizing biologically important compounds,such as cyclic bis（3’-5’） diguanylic acid（c-di-GMP） and its analogues. Atropisomerism of diastereomers generated by the chiral center of the P atom,which results in the doubling of signals in ³¹P NMR.The data of ³¹P NMR at different temperature are presented,and thereafter the reason is discussed.     

Metal ions as selective triggers for removing oligodeoxynucleotide phosphotriester protecting groups

The o-bromophenyl group was successfully tested as a phosphotriester protecting group for internucleotide bonds. This protecting group can be readily and selectively removed using various transition metal salts in aqueous pyridine.     

A new approach to the synthesis of phosphotriester intermediates of nucleosides and nucleic acids

Aryl phosphorodichloridates can be converted by means of 1-hydroxybenzotriazole into an effective phosphorylating agent, which can be applied to the synthesis of phosphotriester intermediates of nucleic acids.     

Synthesis of a teichoic acid fragment of bacillus var.niger w.m. by a phosphotriester approach

Three properly-protected derivatives, one non-terminal and two terminal units, of 3-0-(2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyl)-sn-glycerol have been joined together by two interglyceridic (2→1) phosphotriester linkages to afford, after removal of all protective groups, a teichoic acid fragment.     

Rapid chemical synthesis of d(CACGTG) in milligram amounts by solution-phase phosphotriester chemistry

This paper reports an optimised method for chemical synthesis of short oligodeoxyribonucleotides in milligram amounts by solution-phase phosphotriester chemistry. The procedure is a slight modification of one reported earlier in the literature. Detailed experimental procedures for condensation, deprotection and purification are described. The efficiency of the method is demonstrated by the synthesis of a hexamer, d(CACGTG), in good yields and high purity. The homogeneity of the product and the sequence composition are shown by 270 MHz¹H NMR spectrum.     

Pyrophosphate tetraester intermediate of coupling reactions in the phosphotriester approach to the synthesis of deoxyligoribonucleotides

The intermediate in phosphotriester formation in the presence of ARSO₂Cl, ArSO₂Tet, ArSO₂NT and mixtures of ArSO₂Cl + Tet (Nt, MeIm, DMAP) was established to be pyrophosphate tetraester II.     

Improvements in the phosphotriester synthesis of deoxyribooligonucleotides - the use of hindered amines and a new isolation procedure

Two improvements greatly enhancing the rate of phosphotriester oligonucleotide systhesis were developed: 1) the use of hindered primary amines, e.g. t-butyl amine for decyanoethylation of oligonucleotide triester intermediates, 2) a simplified isolation procedure that eliminates the tedious bicarbonate extraction after each condensing reaction.     

Improved alkylation and product stability in phosphotriester formation through quinone methide reactions with dialkyl phosphates

Investigating reactions of functionalized p-quinone methides continues to advance our design of a reagent being developed for controlled, in situ modification of DNA via phosphodiester alkylation. Previously reported investigations of p-quinone methides derived from catechols allowed for trapping of isolable trialkyl phosphates for characterization and mechanistic information. However, lactone formation with these derivatives required long reaction times, resulting in an unfavorable mixture of trialkyl phosphate and hydrolysis products. To enhance the rate and efficacy of trialkyl phosphate formation and trapping, a phenol derived p-quinone methide has been designed to enforce a conformation favoring lactonization of the dialkyl phosphate alkylated intermediate. The relative rates of phosphodiester alkylation and subsequent trapping of the phosphotriester adduct have been examined by UV and (1)H NMR analysis for p-quinone methide precursor 1 and the corresponding control, 1'. The incorporation of a methyl group at the meta-position of 1 (relative to 1') significantly improves the rate of lactionization to provide a much higher yield of the desired product, lactonized phosphotriester 5. The control reaction with 1' afforded only a minor amount of the corresponding lactonized trialkyl phosphate 5'.     

Novel dinucleoside phosphotriester unit conjugated with an intercalative moiety in a stereospecific manner enhances thermal stability of an alternate-stranded triple helix

A novel phosphoramidite synthon of a dinucleoside phosphotriester unit bearing an intercalative moiety at its internucleotide linkage in a stereospecific manner was prepared and successfully incorporated into the middle portion of α-β chimeric oligoDNA. One of the resulting stereoisomeric chimera DNAs strongly enhances the thermal stability of an alternate-stranded triplex formed between the chimera and a double-stranded DNA.     

A new class of condensing reagents for rapid internucleotide bond formation in the phosphotriester approach and preparation of n3-benzoylthymidine as a key intermediate in oligodeoxyribonucleotide synthesis

Rapid internucleotide bond formation in the phosphotriester approach has been achieved in high yield by use of bis(2,4,6-trihalophenyl) phosphorochloridates (TCP and TBP) as new condensing reagents and the benzoyl group as the N³-imide protecting group of thymidine.     

Quantitation of DNA adduct of thymidylyl(3'-5')thymidine methyl phosphotriester by liquid chromatography/negative electrospray tandem mass spectrometry

A rapid and selective method based on liquid chromatography/electrospray tandem mass spectrometry (LC/ESI-MS/MS) has been developed for the direct quantitation of a methyl phosphotriester DNA adduct, thymidyl (3'-5') thymidine [dTp(Me)dT] from enzymatic hydrolysates of DNA (either in vitro DNA or in cell culture) treated with MNU (N-methyl-N-nitrosourea) or MMS (methyl methane sulfonate). The lower limit of quantitation was 2 ng/mL. Linearity of the calibration curve was greater than 0.999 from 2 to 1000 ng/mL. Intraday precision for four levels of quality controls ranged from 2.8 to 20.1%, and interday precision ranged from 2.9 to 5.6%. This method was used to quantify the levels of dTp(Me)dT in enzymatic hydrolysates of DNA obtained from a series of incubations of salmon testis DNA or mouse lymphoma cells with either MNU or MMS.     

Quantitation of lower levels of the DNA adduct of thymidylyl(3'-5')thymidine methyl phosphotriester by liquid chromatography/negative atmospheric pressure chemical ionization tandem mass spectrometry

A sensitive method has been developed for the direct quantitation of the methyl phosphotriester DNA adduct of thymidyl(3'-5')thymidine (dTp(Me)dT) from enzymatic DNA hydrolysates prepared from cultured cells treated with low levels of N-methyl-N-nitrosourea (MNU) and methyl methane sulfonate (MMS), by rapid and selective liquid chromatography/atmospheric pressure chemical ionization tandem mass spectrometry (LC/APCI-MS/MS). The lower limit of quantitation was 0.1 ng/mL (6.4 adducts per 10(8) nucleotides). Linearity of the calibration curve was greater than 0.999 from 0.1 to 50 ng/mL. Intra-day precision for three levels of quality control samples ranged from 4.27 to 15.62%. Interday precision ranged from 2.46 to 11.95%. Using this method, the levels of dTp(Me)dT in DNA enzymatic hydrolysates obtained from a series of incubations of mouse lymphoma cells with low doses of MNU (50 microM) were quantified.     

Participation of the nucleobases in the regioselective backbone fragmentation of nucleic acids. A molecular dynamics and tandem mass spectrometric investigation on a model dinucleoside phosphotriester

The anions (I–III) obtained from O-methyl 5′-O-(5′-deoxythymidine) 3′-O-(2′,3′-dideoxyuridine) phosphate by the competitive removal of the 3-N-H protons of the nucleobases and of the methyl group from the phosphotriester bond, assume in the gas phase stable conformations as a function of their charge site. The mass-analyzed ion kinetic energy (MIKE) spectra of I and III show that the regioselective backbone cleavage of the internucleotidic linkage is controlled by the 2′-H proton transfer to the nucleobase within the 5′-end nucleoside. Similar pathways are taken by species II when the nucleobase is eliminated as neutral from the 5′-end nucleoside.     

Fast identification by FAB-mass spectrometry of building blocks for oligonucleotide synthesis

Negative ion FAB-MS is recommended for the rapid routine identification of monomeric as well as oligomeric building blocks used in the phosphotriester synthesis of DNA fragments.     

Improved Synthesis of Oligodeoxyribonucleotides by Solid-Phase Phosphotriester Method Utilizing O6-[2-(p-Nitrophenyl)ethyl]-2′-deoxyguanosine Derivatives

The synthesis of oligodeoxyribonucleotides on a cross-linked polystyrene solid support utilizing stable mono- and dinucleotide phosphotriester building blocks is presented. The use of O⁶[2-(p-nitrophenyl)ethyl]-2′-deoxyguanosine derivatives yields cleaner DNA fragments by suppressing side reactions. Modifications improving the phosphotriester methodology are presented. The purification methods and analysis of synthetic oligodeoxyribonucleotides are described.     

New improvements in oligonucleotide synthesis by use of the p-nitrophenylethyl phosphate blocking group and its deprotection by DBU or DBN

Phosphate protection in the phosphotriester approach is improved by the new, versatile p-nitrophenylethyl group due to its stability in the condensation step and its clean removal by DBU and DBN respectively.     

An alternative base-pairing of catechol-bearing nucleosides by borate formation

A chelator-type beta-C-nucleoside having a catechol ligand as the nucleobase was found to form a stable 2:1 complex with trimethyl borate, which was characterized by 1H-NMR and electrospray ionization time-of-flight (ESI-TOF) mass spectroscopies. Both phosphoramidite and phosphotriester derivatives of this nucleoside were also prepared as synthetic precursors for DNA oligomer syntheses.