One-Pot Regioselective Synthesis of 2,6,9-Trisubstituted Adenines.

A series of 2,6,9-substituted adenines were obtained from the easily accessible 5-amino-4-cyanoformimidoyl imidazoles, acetic and benzoic anhydrides, and primary alkyl amines in a three-step sequence. Acylation of 5-amino-4-cyanoformimidoyl imidazoles followed by addition of the amine led to the intermediates 5-amino-4-(N-acyl)formamidino imidazoles under mild conditions. Cyclization of 5-amino-4-(N-acyl)formamidino imidazoles under reflux in ethanol led to the desired substituted adenine. A preliminary stepwise study led to the development of three general and efficient one-pot methods for the synthesis of adenine derivatives. The one-pot, three-step reaction in the presence of DMAP was the most convenient synthetic approach. [ABSTRACT FROM AUTHOR]