Adam Kraszewski

Studies on aryl H-phosphonates. I: An efficient method for the preparation of deoxyribo- and ribonucleoside 3'-H-phosphonate monoesters by transesterification of diphenyl H-phosphonate

Abstract A convenient method for the preparation of deoxyribonucleoside and ribonucleoside 3′-H-phosphonate monoesters via transesterification of diphenyl H-phosphonate with suitable protected nucleosides in pyridine is described.

H-Phosphonates: Versatile synthetic precursors to biologically active phosphorus compounds*

In this review, a short account of H-phosphonate chemistry and its application to the synthesis of biologically important phosphates and their analogs is given.

Studies on aryl H-phosphonates. 3. Mechanistic investigations related to the disproportionation of diphenyl H-phosphonate under anhydrous basic conditions

Abstract Diphenyl H-phosphonate undergoes under anhydrous reaction conditions a base-promoted disproportionation to triphenyl phosphite and phenyl H-phosphonate. On the basis of 31P NMR data the most likely mechanism for this transformation was proposed. In order to substantiate these findings and to get a deeper insight into the chemistry of aryl H-phosphonate esters, we carried out also some studies on activation of phenyl and diphenyl H-phosphonates with various condensing agents. We found that aryl vs alkyl esters of phosphonic acid often follow different reaction pathways during the activation, and this can most likely be traced back to higher electrophilicity of the phosphorus centre and to higher reactivity of the P-H bonds in aryl H-phosphonate derivatives.

Phosphoryl tris-triazole - a new phosphorylating reagent

Abstract Phosphoryl tris-triazole, a new phosphorylating reagent obtained from POCl 3 and 1,2,4-triazole, was found to be very useful for the preparation of nucleoside 3′-phosphotriesters bearing various alkyl phosphate protective groups.

A new synthetic method for the preparation of nucleoside phosphoramidate analogues with the nitrogen atom in bridging positions of the phosphoramidate linkage

Abstract An efficient method for the preparation of nucleoside P3′→N5′ and N3′→P5′ phosphoramidates and their thio analogues results from generation of a pyridine adduct of a nucleoside metaphosphate or its analogue from a nucleoside H-phosphonate, nucleoside H-phosphonothioate or nucleoside H-phosphonodithioate monoester followed by its reaction with 5′- or 3′-aminonucleoside.

Nucleoside Phosphonates. Development of Synthetic Methods and Reagents

Abstract In this paper a short account of our recent research concerning development of new synthetic methods and new reagents for the preparation of DNA and RNA fragments and their analogues is given. #Dedicated to Professor Yoshihisa Mizuno on the occasion of his 75th birthday. ¶Present address: Astra Production Chemicals, S-151 85 Sodertalje, Sweden.

Aryl H-phosphonates. 7. Studies on the formation of phosphorus-carbon bond in the reaction of trityl and benzyl halides with dialkyl and diphenyl H-phosphonates

Abstract The reactions of H-phosphonate diesters with trityl and benzyl halides were investigated using 31P NMR spectroscopy. It was found that extensive oxidation, which usually accompanies the formation of trityl- or p-nitrobenzylphosphonates from the corresponding alkyl bromides in the Michaelis-Becker reaction, can be considerably suppressed or completely eliminated by reacting p-nitrobenzyl or trityl bromides with diphenyl H-phosphonate in acetonitrile in the presence of DBU.

9-Fluorenemethyl H-phosphonothioate, a versatile reagent for the preparation of H-phosphonothioate, phosphorothioate, and phosphorodithioate monoesters

Abstract Simple and efficient synthesis of a new H-phosphonothionylating reagent, 9-fluorenemethyl H-phosphonothioate, was developed. The synthetic utility of the reagent has been demonstrated in the preparations of nucleoside H-phosphonothioate, nucleoside phosphorothioate, and nucleoside phosphorodithioate monoesters.

A proposal for a convenient notation for P-chiral nucleotide analogues. Part 3. Compounds with one nucleoside residue and nonnucleosidic derivatives.

Recently, we have proposed a new DP/LP stereochemical notation for P-chiral dinucleoside monophosphate analogues that permits simple correlation between spatial arrangement of the substituents and the configuration at the phosphorus center. As an extension of this work, we present here applications of the DP/LP notation to derivatives containing only one nucleoside unit (e.g., alkyl nucleoside phosphodiesters, nucleoside phosphomonoesters, cyclic phosphate derivatives, nucleoside di-, and triphosphates) and to nonnucleosidic phosphorus compounds.

The Reactions of H-Phosphonates with Bifunctional Reagents. V. Functionalization of Support-Bound Oligonucleotides and Synthesis of Nonradioactive Hybridization Probes a

Three methods for the functionalization of oligonucleotides with aminoalkyl moieties have been developed and their efficiencies were evaluated in the preparation of non-radioactive hybridization probes.