Stereospecific synthesis of adenosine 3′,5′-(SP)- and -(RP)-cyclic phosphorothioates (cAMPS)

NNO 2 ′-Tribenzoyladenosine 3′,5′-cyclic phosphate (3) was converted into a diastereoisomeric mixture of NNO2′-tribenzoyladenosine 3′,5′-cyclic phosphoranilidates (4); after separation of these diastereoisomers, the corresponding adenosine 3′,5′-cyclic phosphorothioates (1, cAMPS) were obtained and the absolute configuration at the P atom in the diastereoisomers of (4) and (1) was established by 31P n.m.r. spectroscopy.