Concise approach to an unreported class of 5-aryloxy-6-methylaryloxy cytosine analogues

ORGN 384

William C. Trenkle and Julia L. Barkin. Department of Chemistry, Brown University, Box H, Providence, RI 02912

Uracil and cytosine ring systems have received increasing attention due to the efficacy of anticancer drugs, such as 5-fluorouracil, and 5'-deoxy-5-fluorouridine, as well as antiviral agents such as azidothymidine (AZT).  We report a concise route to an unreported class of 5-aryloxy-6Ðmethylaryloxy cytosine derivatives in four high yielding steps from commercially available aryl alcohols.  In a key step, cyanomethyl ethers (general structure 1) derived from the aryl alcohols undergo an efficient Thorpe condensation to provide b-enamino-nitrile 2 in 85-99% isolated yield.  This report showcases the ability of the Thorpe condensation to provide an efficient route to b-enamino-nitriles from cyanomethyl ethers. The b-enamino-nitriles 2 are readily converted into disubstituted cytosines 3.  Intramolecular Thorpe-Ziegler condensation of the catechol derived di-cyanomethyl ether 4 followed by elaboration provides the benzodioxapine fused pyrimidine 5.   Further work is underway to examine the scope and versatility of this approach toward cytosine analogues as well as elucidate the biological activity of these interesting new analogues.