Design, synthesis and binding affinity of 3′-fluoro analogues of Cl-IB-MECA as adenosine A3 receptor ligands

Several 3'-fluoro analogues, la, 1b, and le of selective and potent adenosine A(3) receptor agonist, Cl-IB-MECA were synthesized from D-xylose via highly regioselective opening of lyxo-epoxides, 8a and 811 with fluoride anion. Compared to the high binding affinity of Cl-IB-MECA to the A(3) adenosine receptor, the corresponding 3-fluoro derivative showed remarkably decreased binding affinity, indicating that 3'-hydroxyl group acts as hydrogen bonding acceptor, not hydrogen bonding donor like fluorine atom in binding to the A(3) adenosine receptor. (C) 2003 Elsevier Science Ltd. All rights reserved.