New methods for multiple modifications of a phosphorus centre. Their relevance to nucleotide and oligonucleotide analogues synthesis

Nucleoside phosphoramidates and their analogues with the P-N bond in bridgi ng positions of the phosphoramidate linkage were prepared by a new method u tilizing the corresponding pyridine adducts of metaphosphates. Also, a new procedure was developed for the synthesis of unprotected nucleoside phospho romono- and phosphorodithioates.