Synthesis of Acyclic Nucleotide Analogues Derived from 2-Amino-6-C-substituted Purines via Cross-Coupling Reactions of 2-Amino-9-{2-[(diisopropoxyphosphoryl)methoxy]ethyl}-6-halopurines with Diverse Organometallic Reagents

Cross-coupling reactions of 2-amino-6-chloro-9-{2-[(diisopropoxyphosphoryl)methoxy]ethyl}purine ( 1 ) and 2-amino-9-{2-[(diisopropoxyphosphoryl)methoxy]ethyl}-6-iodopurine ( 2 ) with diverse types of organometallic reagents have been studied. Arylboronic acids reacted with 1 to give the corresponding 2-amino-6-arylpurines 3a - 3d in good yields. Analogously, trialkylaluminium reagents were used for the preparation of 6-alkyl-2-aminopurines 3k and 3l from 1 . Hetarylzinc halides and hetarylstannanes required the use of 2-amino-6-iodopurine 2 to give the corresponding 2-amino-6-hetarylpurines 3e - 3j in fair to good yields. A CuI/KF mediated coupling of perfluoroalkylsilanes with 2 afforded the 2-amino-6-perfluoroalkylpurines 3m and 3n in moderate yields. Cleavage of the esters 3 with bromo(trimethyl)silane gave the target free phosphonates 4 that were purified by ion- exchange chromatography. The title compounds were tested on antiviral and cytostatic activity.