Divergent Synthesis of F- and CF₃-Containing N-Fused Heterocycles Enabled by Fragmentation Cycloaddition of -CF₃-1,3-Enynes with N-Aminopyridiniums Ylides

The two novel cyclization modes of beta-CF3-1,3-enynes are presented herein for the divergent construction of F- and CF3-containing N-fused heterocycles. Fluorinated pyrazolo-[1,5-a]-pyridines were afforded from beta-CF3-1,3-enynes with N-aminopyridiniums ylides via detrifluoromethylative [2 + 3] cyclizations, followed by fluorine transfer from a CF(3)unit. Whereas reaction with N-aminoisoquinoliniums ylides gave CF3-substituted pyrrolo-[2,1-a]-isoquinoline by unprecedented fragmentation [3 + 2]-cycloadditions. Additionally, gram-scale experiments and synthetic utility are demonstrated by further derivatization of fluorinated heterocycles.