Synthesis of 5'-O-amino-2'-deoxypyrimidine and purine nucleosides: Building-blocks for antisense oligonucleosides
An efficient synthesis of 5'-O-amino-2'-deoxy analogs of uridine 1, thymidine 2, cytidine 3, 5-methylcyitidine 3a, adenosine 4, and guanosine 5 was accomplished. The key step of 5'-O-N-bond formation in 2'-deoxynucleosides 1-5 was achieved via a Mitsunobu reaction in excellent yields. The 5'-O-amino nucleosides 1-5 are useful building-blocks for the synthesis of nucleoside dimers linked by a methylene(methylimino) (MMI) bridge. MMI is a novel phosphate surrogate for antisense oligonucleosides.