Stereoselective Synthesis of (R P )-8-Substituted-N 6 -acylated and N 6 -Alkylated Adenosine-3',5'-cyclic Phosphorothioic Acids as cAMP Antagonists. -A strategy for the stereoselective preparation of N 6 -substituted (RP)-adenosine-3',5'-cyclic monophosphorothioic acids from cAMP is developed. The interim conversion into tributyl ammonium salts (VIII) is due to their enhanced solubility in several organic solvents; these salts are more applicable for chromatographic purification. N-Acyl dervatives are prepared similarly. Unfortunately, both N 6 -alkylation and N 6 -acylation lead to reduced protein kinase A antagonist activity. -(ANDREI, M.; BAKKEBOE, T.; KLAVENESS, J.; TASKEN, K.; UNDHEIM*, K.; Eur. J. Med. Chem. 46 (2011) 12, 5935-5940, http://dx.