Pyrimidine Derivatives and Related Compounds. XLIX. Reaction of Anhydrouridines with the Vilsmeier Reagent

Abstract

Treatment of O², 2'-anhydrouridine (1) with phosphorus oxychloride in dimethylformamide (DMF) at 60°C afforded both 2', 5'-dichloro-2', 5'-dideoxyuridine (2a) and 2', 5'-dichloro-2', 5'-dideoxy-3'-O-formyluridine (3a). The reaction of 1 with phosphorus oxybromide in DMF gave the corresponding 2', 5'-dibromo derivatives (2b) and (3b). O², 5'-Anhydro-2', 3'-O-isopropylideneuridine (4) was treated with the Vilsmeier reagent (DMF/POX₃) to give the corresponding 5'-halogeno-5'-deoxy-2', 3'-O-isopropylideneuridines (5a and 5b) in high yields. Under the same conditions, the reaction of 6, 5'-cyclo-2', 3'-O-isopropylideneuridine (6) with the Vilsmeier reagent (DMF/POX₃) afforded the corresponding 1-(5-halogeno-5-deoxy-2, 3-O-isopropylidene-β-D-ribofuranosyl)-5-dimethylaminomethylenebarbituric acids (7a and 7b) in high yields.