ChemInform Abstract: Benzopyrones. Part 21. Sulphonamide, Sulphonylurea, Urea, and Carbamate Derivatives of Chromen-4-ones.

ChemInform Abstract

Chromen-4-ones bearing the fcitle groups have been synthesized. Chlorosulphonation of a n-deficient ring system such as chromen- 4-one requires the presence of electron-releasing substituents; attempts to Chlorosulphonate the chromen-4-one (I) gives a low yield of the sulphonyl Chloride (IIIa), which affords the sulphonamide (IIIb) followed by reaction with (IVa) to give the carbamate (IIIc). Diazotization of a primary amino group as in (V) [-+ (VI)] followed by treatment with SO₂ and CuCl₂ is a more successful and versatile method of synthesizing the sulphonyl chlorides (VII) yielding the sulphonamides (VIII) or the carbamate (IX) compared to the method used to prepare (IIIa). Starting from the amines (X), (Va) or (Vb) the compounds (XI) (XII) (potential anthelminthics), (XIV) or (XV) are prepared. The amino nitro compound (XVIII) is synthesized from the carbamate (XVI).