Derivatization and biological activity studies of 3-chloro-3-chlorosulfenyl spiro tetrahydropyran/tetrahydrothiopyran-4,2'-chroman-4'-one

The adducts 4a,b-7a , b have been obtained either by reducing α -chloro- β -oxosulfenyl chlorides 2a,b with iodide ion in the presence of dienes namely, 2-methyl-1,3-butadiene (isoperene), 2,3-dimethyl-1,3-butadiene, 1,2,3,4-tetrachlorocyclopentadiene, or 1,3-cyclohexadiene, respectively; or by thermolysis of oxadithiin derivatives 3a,b in the presence of the same aforementioned dienes presumably via the formation of the same intermediate A in both cases of compounds 2a,b and 3a,b . It is observed that α -chloro- β -oxosulfenyl chlorides 2a,b undergo straight forward substitution with potassium cyanide to give 8a,b . Direct oxidation of 2a,b with H 2 O 2 /AcOH affords 3,3-dichloropyran-4-ones 9a,b , while conversion of 2a,b to the sulfonamides 10a,b followed by oxidation provides 3-chloropyranones 11a,b . Antioxidant and antimicrobial evaluation of compounds 4a,b-6a,b shows moderate activiy. MIC of the derivative 6b reveals a remarkable inhibition of the pathogenic gram positive bacteria ( Staphylococcus aureus ) as well as gram negative E coli .