C(5′)-ethynylated adenosine derivatives 5, 6, 11, and 12 (Scheme 4). Similarly, the 5′-epimeric dimer 16 was prepared by coupling 3 with the alkyne 8 (Scheme 5). The propargylic alcohol 4 was transformed into the N-benzoylated alkyne 5 and into the amine 6, while the epimeric alcohol 7 was converted to the epimeric amine 8 and the 5′-deoxy analogues 11 and 12 (Scheme 3). Cross-coupling of the iodoadenosine