Disclosed is a compound of formula I:
[wherein B is a nucleobase selected from the group consisting of adenine, guanine, cytosine, uracil and hypoxanthine], a compound of formula II:
[wherein B' is a nucleobase selected from the group consisting of adenine, guanine, cytosine, thymine, uracil and hypoxanthine],
a method for synthesizing these nucleoside triphosphates, and a process for producing an oligonucleotide using these nucleoside triphosphates.