Reactions of tethered, tertiary sulfonamides with thermally generated benzynes are reported. Typically, the N-S bonds in the substrates cleave, and saturated heterocycles [tetrahydroquinolines (n = 2) and indolines (n = 1)] are formed. The process is accompanied by either sulfonyl transfer or desulfonylation from a zwitterionic intermediate, with the favored pathway being largely dependent upon the size (5- vs 6-membered) of the N-containing ring in the zwitterion.
Bibliographical noteFunding Information:
Support for this research was provided by the National Institutes of General Medical Sciences of the U.S. Department of Health and Human Services (R01 GM65597, then R35 GM127097). L.Z. received support from the China Scholarship Council Program (201706175084). A portion of the NMR spectral data were acquired with an instrument purchased with funds provided by the NIH Shared Instrumentation Grant program (S10OD011952). The X-ray diffraction analysis was performed by Dr. Victor G. Young (University of Minnesota).