Jan Heliński

Branched polyether with multiple primary hydroxyl groups: polymerization of 3-ethyl-3-hydroxymethyloxetane

Cationic polymerization of 3-ethyl-3-hydroxymethyloxetane gives branched, soluble macromolecules with multiple glycolic end groups. There are approximately 3–4 “normal” units per one branched unit.

N,N-diisopropyl-O-P-nitrophenyl-P-methylphosphonoamidite: novel difunctional PIII reagent in oligonucleoside methylphosphonate synthesis containing 4-nitrophenoxy group

Abstract First example of the PIII coupling reagent containing 4-nitrophenoxy group is described. Its usefulness is demonstrated by synthesis of dinucleoside methylphosphonate and methylthiophosphonate.

Efficient oxygenation of thiophosphoryl and selenophosphoryl groups using trifluoroacetic anhydride

Abstract Trifluoroacetic anhydride reacts with organophosphorus compounds containing thiophosphoryl and selenophosphoryl groups converting them in high yield to the corresponding oxygenated systems.

Convenient synthesis of propane aminophosphonic acids, aminodiphosphonic acids and their structural analogues, mediated by azetidinium salts

Abstract The reactions of azetidinium salts with phosphorus nucleophiles R2P(O)H have been investigated. Treatment of O-benzyl-N,N-diethyl-3-hydroxyazetidinium salt 2 with R2P(O)H in the presence of sodium hydride gave the corresponding γ-N,N-diethylamino-β-benzyloxypropylphosphonate 6a or phosphine oxide 6b. After debenzylation γ-N,N-diethylamino-β-hydroxypropylphosphonate 3a and phosphine oxide 3b were obtained. The compound 6a was converted into its sulfonate ester 8 which underwent elimination to yield 4. The structure 4 has been employed in Michael addition of R2P(O)H to form compounds 5 containing two phosphorus centers. Further compounds of type 3 have been transformed into compounds 5 by reaction with R2P(O)H in the presence of 1.1 equivalents of NaH in boiling toluene. Finally, azetidinium salts 1 have been converted into compounds 5a by reaction with two equivalents of R2P(O)H in the presence of 2.1 equivalents of NaH. Molecular mechanics with implementation of the Allinger MM2 force field and semiempirical AM1 and PM3 methods were used to investigate structures 5d and 5f.

Ring-opening of 3-benzyloxyazetidinium salts with organophosphorus nucleophiles Application to the synthesis of poly functional aminophosphonic acids analogues

Abstract Novel and efficient synthesis of polyfunctional γ- and δ-aminophosphonic acids derivatives via ring opening of 3-alkoxyazetidinium salts with phosphorus containing nucleophiles is described.

New phosphitylating reagent in the nucleotide chemistry containing two 4-nitrophenoxy leaving groups. Remarkably fast and clean phosphitylations activated by DBU leading to thio- and seleno-oligonucleotides

Abstract A new synthetic approach to modified oligonucleotides based on N,N′-diisopropyl-di-(4-nitrophenyl)phosphoroamidite 1 is described. The procedure involves displacement of either 4-nitrophenoxy or diisopropylamino ligands. The former proceeds very fast in the presence of DBU, the latter requires activation by tetrazole. This method allows rapid and almost quantitative construction of modified nucleotides derived from thio- and selenophosphorus acids.

Synthesis of polyfunctional phosphorodithioates and structural analogues mediated by azetidinium ions and epoxides

Abstract The nucleophilic ring opening reactions of N , N- dialkyl-3-hydroxy(benzyloxy)azetidinium salts 1 and N , N -dibenzyl-2,3-epoxypropylamine 10 with anions of mono- and dithioacids of phosphorus 2 affords phosphorodithioates (and structural analogues) 3 and 11 possessing S -propyl substituents incorporating 2-hydroxy and 3-dialkylamino functionalities. A strong dependence of the stability of these compounds on structural factors is discussed.

N, N-Diisopropyl-O-Methyl-O-4-Nitrophenyl Phosphoramidite. New Flexible Phosphitylating Reagent in the Synthesis of Thio- and Seleno- Oligonucleotides

Abstract Internucleoside coupling by the title reagent, illustrated by synthesis of dinucleoside and trinucleoside thiophosphates and selenophosphates is accomplished by a new strategy involving the displacement of 4-nitrophenoxy group. Sodium 4-nitrophenolate formed in situ facilitates the oxidation of the intermediate pIII structures and acts as a demethylating reagent.

Synthesis of multifunctionalized phosphonic acid esters via opening of oxiranes and azetidinium salts with phosphoryl-substituted carbanions

Ring-opening of N,N-diethyl-3-benzyloxyazetidinium salt 1b and N,N-dibenzyl-2,3-epoxypropylamine 6 by phosphoryl-substituted carbanions generated from phosphonates 2a–e furnishes the multifunctional phosphonates 3a–e and 7a, 7b, 7e bearing the same carbon skeleton. The reaction of the heterocyclic electrophiles 1b and 6 with the P-allyl anion generated from 2f demonstrates the strong dependence of the α/γ-regioselectivity on the reaction conditions. Depending on the character of the electrophile and/or the reaction medium the regioselective synthesis of both α- and γ-regioisomers is realized.

New phosphitylating reagents containing aryloxy leaving group. Applications in nucleotide chemistry

Abstract Synthetic oligonucleotides bearing modifications in the backbone have potentials as tools in studying and controlling biological processes.