The first examples of direct glycosidation of the 5'-OH end of polypyrimidi
ne oligonucleotides still attached to the CPG solid support are reported. A
general re-elongation solid phase procedure has been developed to successf
ully isolate the target 5'-glycosyl derivatives. A 3',5'-diglucosylated 16-
mer oligonucleotide has also been obtained.