Alkyl Shifts in 1,4‐Dipoles from Tosyl Iso(thio)cyanate and Imido(thio)carbonates or Isoureas

Abstract

Abstract O → N alkyl shifts are observed in the dipoles 3, 13 from tosyl isocyanate ( 2a ) and imido(thio)carbonates 1 ( 12 ) to give (thio)allophanates 5 ( 14 ). Similarly, addition of tosyl isothiocyanate ( 2b ) to isourea 24a leads to the product 28 of an O → S methyl shift. A cross‐over experiment involving 2a and imidothiocarbonates 12b,c gives the four products 14a–d proving the intermolecular nature of the rearrangement. However, on mixing 2a and isoureas 24a,b or 2b and imido(thio)carbonates 1 ( 12 ), the reaction stops at the stage of dipoles 8, 19, 25a,b .