Synthesis of a formamidine-protected 5′-amino-2′,5′-dideoxyguanosine phosphoramidite and preparation of 5′-acylamidooligonucleotides

A 5′-amino-2′,5′-dideoxyguanosine phosphoramidite building block for DNA synthesis was prepared from 2-N-(dibutylformamidino)-2′-deoxyguanosine in four steps and 68% overall yield. Two of the three steps of the conversion from the 5′-alcohol to the monomethoxytritylamine were performed in the same flask.