New method for the preparation of 3'- and 2'-phosphoramidites of 2'- and 3'-difluoromethyleneuridine

Article abstract of DOI:10.1016/0040-4020(96)00364-X

The one step reaction of 2'- and 3'-keto derivatives of uridine 2a, 2b, 7a and 7b with bromodifluoromethyl[tris(dimethylamino)]phosphonium bromide (13) and zinc gives the corresponding 2'- and 3'-difluoromethylene nucleosides 3a, 3b, 8a and 8b in good yield. Removal of the silyl groups affords difluoromethylenated uridines 4a, 4b, 9a and 9b. Phosphitylation of 4a and 9a provides the target 2'- and 3'-phosphoramidites 5 and 10 for use in oligonucleotide synthesis.