Nucleoside 3'-phosphotriesters as key intermediates for the oligoribonucleotide synthesis. IV. New method for removal of 2,2,2-trichioroethyl group and31NMR as a new tool for analysis of deblocking of intemucleotide phosphate protecting groups

Zinc/acetylacetone/pyridine treatment has been designed as a very efficient method for removal of 2,2,2,-trichloroethyl group from phosphoesters. Internucleotide and terminal 2,2,2-trichloroethylphosphotriesters were transformed to corresponding diesters quantitatively. Much less reactive 2,2,2-trichloroethylphosphodiesters produced monoesters with ca. 90% yield. 31P NMR spectroscopy has been proposed as a new tool for analysis of removal of internucleotide phosphate protecting groups-a crucial step in oligonucleotides synthesis via phosphotriester approach.