A Convenient and Efficient Method for the Synthesis of Nucleoside H-Phosphonates Using a Novel Phosphonylating Agent

Abstract

In the present paper we describe the preparation of a novel crystalline phosphonylating agent 9-fluorenemethyl phosphonic acid 2 and a convenient and efficient method for the synthesis of nucleoside H-phosphonates 5.     

Studies on Aryl H-Phosphonates. Synthesis of Nucleoside N-Alkylphosphonamidates

Abstract

The aminolysis of aryl nucleoside H-phosphonate diesters with various amines was studied. The new simple and efficient method of synthesis of nucleoside phosphonamidates is described.     

Thermal Synthesis of Nucleoside H-Phosphonates Under Mild Conditions

Nucleosides react rapidly with ammonium phosphite ((NH₄)₂HPO₃) at 60 °C to produce good yields of nucleoside-5-phosphite monoesters within 24 h. Under the same conditions, ammonium phosphate is unreactive, producing low yields of nucleotide only after extended reactions. These results confirm earlier suggestions that nucleoside H-phosphonates and their possible condensation products may have been produced on the primitive earth more easily than nucleotides.     

The Use of Nucleoside H-Phosphonates in the Synthesis of Deoxyoligonucleotides

Abstract

Nucleoside H-phosphonates are valuable intermediates in the synthesis of deoxyoligonucleotides. The DBU salt form is more stable in solution and is consequently an improvement in routine synthesis of DNA.     

Nucleoside H-Phosphonates. IX. Possible Side-Reactions During Hydrogen Phosphonate Diester Formation

Abstract

Possible side-reactions during hydrogenphosphonate diester formation in the presence of various condensing reagents (e.g. arensulfonyl derivatives, chlorophosphates and acyl chlorides) have been investigated using ³¹P NMR spectroscopy.     

Aryl Nucleoside H-Phosphonates—Novel Derivatives of Controlled Reactivity

Abstract

The most essential factors influencing the formation of aryl nucleoside H-phosphonates are discussed.

Recently, aryl nucleoside H-phosphonates (1) (Scheme 1) emerged as a new type of intermediates in the synthesis of phosphate derivatives¹. In contradistinction to other reactive species derived from H-phosphonate monoesters, these compounds bear only one electrophilic centre (located on phosphorus) and their reactivity can be modulated by substituents on the aromatic ring².     

A Mild Method for the Preparation of Nucleoside Phosphorofluoridate and Phosphorofluoridothioate Diesters

Abstract

Synthesis of unprotected dinucleoside phosphorofluoridate and phosphorofluoridothioates from the corresponding phosphorothioate and phosphorodithioate derivatives is described.     

Studies on Reactions of Nucleoside H-Phosphonates with Bifunctional Reagents. Part VI. Reaction with Diols

Abstract

Reactions of nucleoside H-phosphonates with various diols using different types of condensing agents have been studied. Depending on the coupling procedure and the length of a polymethylene chain of the diol, acyclic H-phosphonate diesters or cyclic phosphite triesters were formed. The course of oxidation with iodine to produce cyclic nucleoside alkyl phosphotriesters or hydroxyalkyl nucleoside phosphodiesters can be controlled by the amount of water present in the reaction medium.     

Studies on Reactions of Nucleoside H-Phosphonates with Bifunctional Reagents. Part III. Further Studies on Transesterification of Nucleoside H-Phosphonate Diesters with Amino Alcohols

Abstract

Reactions of 5′-O-(4,4′-dimethoxytrityl)thymidin-3′-yl 2-cyanoethyl phosphonate with alcohols, amines and amino alcohols in pyridine are described Transesterification was found to be faster than β-elimination of 2-cyanoethyl group     

Note: A Convenient Method for the Preparation of N2, N2-Dimethylguanosine

Abstract

The preparation of N², N²-dimethylguanosine is described. The use of the 2-(p-nitrophenyl)ethyl group instead of the benzyl protecting group for the O⁶ position of the guanine ring resulted in better yields and shorter protocols.     

2-Cyanoethyl H-Phosphonate. A Reagent for the Mild Preparation of Nucleoside H-Phosphonate Monoesters

Abstract

2-Cyanoethyl H-phosphonate was condensed with protected nucleoside derivatives and the cyanoethyl group subsequently removed by anhydrous base to give the corresponding nucleoside H-phosphonate in good yield.     

A Simplified and Convenient Method for the Double-Embedding of Tissues

A method for embedding tissues with a celloidin-paraffin combination is presented. The essential features of the process depend upon (1) a thorough infiltration of the specimen with celloidin of low concentration, and (2) the subsequent impregnation of both the specimen and the celloidin with paraffin.

The methods for sectioning, and the removal of the embedding agent are given.

The chief advantages of this method are: the preservation of all of the advantages of celloidin embedding but with a great saving of time, and greater convenience of storage; the cutting of thin sections (2μ for many types of tissues); it is useful for embedding specimens for which neither pure paraffin nor pure celloidin are entirely satisfactory, i.e. those containing tissues differing in density.     

A Convenient Method for the Quantitative Determination of Pipecolic Acid

The quantitative determination of pipecolic acid was examined.

The reaction of 3% ninhydrin solution in n-butanol, saturated with citrate buffer (pH 4.2), with pipecolic acid in boiling water for 3 min yielded the colored products showing λ_max at 570 mμ, but with proline hardly yielded those products. By the colorimetry proposed, it is possible to determine the amount of pipecolic acid in the sample containing proline no more than 50 times the amount of the pipecolic acid, directly from the calibration curve using pipecolic acid.

The method for removal of amino acids from the sample containing pipecolic acid and proline was examined and discussed.     

人脑神经元特异性烯醇化酶的纯化方法

采用改良的Grace层析方法,经一次DEAE-Sephadex A50柱层析即从人脑中纯化了神经元特异性烯醇化酶,比活力为92.1U/mg,纯化倍数为59.4.该酶纯化后,经SDS-聚丙烯酰胺凝胶电泳鉴定为单一蛋白质谱带.此外,还测定了其部分理化性质,其亚单位分子量为45000,等电点pI为4.7,氨基酸组成分析表明其为一种酸性蛋白质;对2-磷酸甘油酸的K_m值为5.6×10^-4mol/L.     

一种便于丝状真菌显微观察的培养方法

在真菌培养过程中,对其个体形态与群体（菌落）形态进行实时观察与鉴定是很必要的。本文利用半培养基培养法结合显微操作技术,对丝状真菌个体与群体进行形态学观察。结果表明,该方法无需染色与制片,不破坏菌丝正常生长状态,可实时进行形态学检测,对多个菌种在自然生长状态下的菌丝与菌落特征进行观察,操作简单、方便、快捷,从而降低了成本及工作量。     

A Convenient Method for the Synthesis of ATP and Ap4A

Abstract

A bifunctional phosphorylating reagent, O-8-(5-chloroquinolyl) S-phenyl phosphorothioate (1) was employed for the synthesis of adenosine 5′-triphosphate (ATP) and diadenosine 5′-tetraphosphate (Ap₄A) from adenosine 5′-phosphate (AMP) on a large scale.     

Nucleoside H-Phosphonates. V. The Mechanism of Hydrogenphosphonate Diester Formation Using Acyl Chlorides as Coupling Agents in Oligonucleotide Synthesis by the Hydrogenphosphonate Approach

Abstract

The H-phosphono-acyl mixed anhydrides of type III were found to be the main intermediates during H-phosphonate diester formation using acyl chlorides as coupling agents in the reaction of hydrogenphosphonate monoesters with hydroxylic components.