Solid‐phase synthesis of oligodeoxynucleotides containing 4‐alkoxythymidine residues

Immobilized and fully protected oligodeoxynucleotides containing a 4‐(1,2,4‐triazolyl)‐thymidine residue at a predetermined position were prepared according to a well‐established phosphite triester methodology using 2‐cyanoethyl phosphoramidites of a 4‐(1,2,4‐triazolyl)‐substituted thymidine and standard protected nucleosides. Treatment of the immobilized oligomer with methanol, ethanol or n ‐propanol in the presence of DBU at 50°C gave the corresponding oligonucleotides containing 4‐methoxy, 4‐ethoxy‐ or 4‐ n ‐propoxythymidine residue.