xidative addition of N-aminophthalimide to 3,4-dihydro-2H-thiopyrans, their S-oxides, and S,S-dioxides

Selectivity of nitrene addition to the C C S fragment depends on the oxidative state of the sulfur atom as has been exemplified on various derivatives of 3,4-dihydro-2 H -thiopyran under conditions of oxidative aminoaziridination. A unique structure with 2-thia-7-azabicyclo[4.1.0]heptane-2,2-dioxide core was obtained via addition of nitrene to the C C bond of thiopyran S , S -dioxide. For an unoxidized thiopyran, only en(phthaloyl)hydrazine resulted after cleavage of the initially formed aziridine. S -Oxide trapped the nitrene by the sulfur atom to form the sulfoximine leaving the double bond unaffected.