Convenient Syntheses of 3′-Amino-2′,3′-dideoxynucleosides, Their 5′-Monophosphates, and 3′-Aminoterminal Oligodeoxynucleotide Primers

5'-Protected 3'-amino-2',3'-dideoxynucleosides containing any of the four canonical nucleobases (A/C/G/T) were prepared via azides in five to six steps, starting from deoxynucleosides. For pyrimidines, the synthetic route involved nucleophilic opening of anhydronucleosides. For purines, an in situ oxidation/reduction sequence, followed by a Mitsunobu reaction with diphenyl-2-pyridylphosphine and sodium azide, provided the 3'-azidonucleosides in high yield and purity. For solid-phase synthesis of aminoterminal oligonucleotides, aminonucleosides were linked to controlled pore glass through a novel hexafluoroglutaric acid linker. These supports gave 3'-aminoterminal primers in high yield and purity via conventional DNA chain assembly and one-step deprotection/release with aqueous ammonia. Primers thus prepared were successfully tested in enzyme-free chemical primer extension, an inexpensive methodology for genotyping and labeling. Protected 5'-monophosphates of 3'-amino-2',3'-dideoxynucleosides were also prepared, providing starting materials for the preparation of labeled or photolably protected monomers for chemical primer extension.