Solvent extraction method used in separating the protected product of synthetic oligodeoxyribonucleotides

A solvent extraction method for separating synthetic protected oligodeoxyribonucleotides was used in our laboratory based on the lipophilic property of the protecting group of 5'-OH of the oligomers. The extraction of synthetic products protected with MMTr is complete by ether or ether-chloroform (6:1 V/V) for mononucleosides, by chloroform for dinucleoside monophosphates, by dichloromethane:n-butanol (4:1 V/V) for trimer or tetramer, and is nearly complete by dichloromethane:n-butanol (2:1 V/V) for hexamer. The 5'-end phosphorylated nucleotides, oligonucleotides and their symmetrical pyrophosphates remain in water phase. The following synthetic products of protected oligodeoxyribonucleotides have been isolated with this method, all above 85% in purity: (Formula: see text).