Synthesis of Pyrazolo[1,5- a ]pyridinyl, Pyrazolo[1,5- a ]quinolinyl, and Pyrazolo[5,1- a ]isoquinolinyl Sulfonyl Fluorides via a [3 + 2] Annulation.

A [3 + 2] cycloaddition reaction of N -aminopyridines, N -aminoquinolines, and N -aminoisoquinolines with 1-bromoethene-1-sulfonyl fluoride (BESF) was performed to obtain optimum yields of various useful pyrazolo[1,5- a ]pyridinyl, pyrazolo[1,5- a ]quinolinyl, and pyrazolo[5,1- a ]isoquinolinyl sulfonyl fluorides (43-90% yield). The transformation process showed broad substrate specificity, mild reaction conditions, and operational simplicity. Therefore, the reaction has great applicable value in the field of medicinal chemistry and other disciplines.