Synthesis and biological evaluation of a series of thieno-expanded tricyclic purine 2′-deoxy nucleoside analogues

Introducing structural diversity into the nucleoside scaffold for use as potential chemotherapeutics has long been considered an important approach to drug design. In that regard, we have designed and synthesized a number of innovative 2′-deoxy expanded nucleosides where a heteroaromatic thiophene spacer ring has been inserted in between the imidazole and pyrimidine ring systems of the natural purine scaffold. The synthetic efforts towards realizing the expanded 2′-deoxy-guanosine and -adenosine tricyclic analogues as well as the preliminary biological results are presented herein.