Tetramethylolglycoluril mediated C3 sulfonylmethylation of pyrazolo[1,5-a]pyrimidines under transition metal-free conditions

Abstract

HFIP (1,1,1,3,3,3-hexafluoropropan-2-ol) promoted transition metal-free protocol for regioselective C3 sulfonylmethylation of pyrazolo[1,5-a]pyrimidines by using tetramethylolglycoluril as a nontoxic, in situ C1 source and sodium sulfinate salts has been developed. This methodology is operationally simple, cost-effective, and environmentally benign, and affords sulfonylmethylated products in moderate to good yields. Mechanistic studies suggest that the reaction proceeds via an ionic path.