4‑Toluenesulfonyloxymethyl‑(H)‑phosphinate: A Reagent for the Introduction of O- and S‑Methyl‑(H)‑phosphinate Moieties

The straightforward synthesis of sodium 4-toluene­sulfonyl­oxymethyl-(H)-phosphinate and (H)-phosphino­methyl­isothio­uronium tosylate as new reagents for the preparation of O- and S-methyl-(H)-phosphinic acid derivatives, respectively, is described. The reactivity of both reagents was demonstrated by the preparation of protected 2′-deoxy­ribonucleo­side-O-methyl-(H)-phosphinates in the 5′- and 3′-series and 2′,5′-dideoxy­ribonucleo­side-5′-S-methyl-(H)-phosphinates. These compounds represent a new class of monomers compatible with the solid phase synthesis of oligonucleotides by H-phosphonate chemistry, as it was proved with the synthesis of a fully phosphonate heptamer.