STEREOCONTROLLED SYNTHESIS OF THE FOUR STEREOISOMERIC DIPHOSPHORYLPHOSPHONATES OF CARBOCYCLIC 2',3'-DIDEOXY-2',3'-DIDEHYDRO-5'-NORADENOSINE

Abstract A flexible synthesis of the four stereoisomeric enantiomerically pure 5′-nor carbocyclic adenosine analogues 4b , ent - 4b , 5b and ent - 5b starting from the common enantio-merically pure allylic monoacetate 3 has been developed. Each of the nucleoside analogues was transformed into the corresponding 4′-phosphonates and subsequently into the diphosphoryl-phosphonates 4e , ent - 4e, 5e , and ent - 5e , respectively.