Bromination of highly unsaturated trifluoromethanesulfonamide derivatives

Abstract

The bromination of trifluoro-N-(prop-2-yn-1-yl)methanesulfonamide with molecular bromine gives a mixture of Z- and E-isomeric N-(2,3-dibromoprop-2-en-1-yl)trifluoromethanesulfonamides, regardless of the reaction conditions. Bromine adds to both triple bonds of trifluoro-N,N-bis(prop-2-yn-1-yl)methanesulfonamide, yielding a mixture of N-(2,3-dibromprop-2-en-1-yl)trifluoro-N-(prop-2-yn-1-yl)methanesulfonamide, N,N-bis(2,3-dibromoprop-2-en-1-yl)trifluoromethanesulfonamide, and trifluoro-N,N-bis(2,2,3,3-tetrabromopropyl) methanesulfonamide. Diacetylenic trifluoromethanesulfonamide derivative, N,N′-hexa-2,4-diyne-1,6-diylbis( trifluoromethanesulfonamide), reacts with bromine to afford N,N′-[(2E,4E)-2,3,4,5-tetrabromohexa-2,4-diene-1,6-diyl]bis(trifluoromethanesulfonamide) and isomeric N-(2,3-dibromoprop-2-en-1-yl)trifluoromethanesulfonamides resulting from reductive cleavage of the central C–C bond in the former.