Synthesis of 2-(β-D-Ribofuranosyl)Thiazole-4-Carboxamide 5′-Phosphate Isosteres

Abstract SUMMARY. The syntheses of 5′-O-sulfamoyl and 5′-O-carbamoyl tiazofurin (9 and 12) are described. One pot reaction of 2′, 3′-O-isopropylidene-tiazofurin (7) with hexabutyldistannoxane and sulfamoyl chloride gave the corresponding 5′-O-sulfamoyl ester, which was deprotected to yield 9. Compound 7 reacted with phenyl chloroformate to give the 5′-O-carbophenoxy derivative which on treatment with ammonium hydroxide followed by deisopropylidenation afforded 12. Improvements on the synthetic route to the starting tiazofurin are also reported.