The addition of amines to bis(Ppropyny1) sulfone (3) led to mixtures of 2H-thiopyran 1,l-dioxides, substituted at carbons 3 or 5 with the respective amino residue. Hydrolysis of these cyclic dienamine mixtures afforded a single ketone, viz., 3-methyl-5-oxo-AS-dihydrothiopyran 1,l-dioxide (7). Under appropriate conditions the addition of morpholine to 3 gave the monoadduct 2-N-morpholinyl-1-( 2-propynylsulfony1)propene (9), whereas the addition of dimethylamine yielded the diadduct bis( 2-dimethylamino-1-propenyl) sulfone (8b). Both were readily converted into the respective mixtures of the cyclic dienamines above. A mechanism for the cyclization is discussed. Furthermore, a number of propargylic sulfides, sulfoxides, and sulfones are described. The products from reactions of the sulfones with nucleophilic reagents are recorded.
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