Kemp-type Elimination of 1-Arylsulfonyl-3-iodo-1h-indazoles

An intriguing ring-opening reaction of 1-arylsulfonyl-3-iodo-1H-indazoles, which can afford the corresponding ortho-(arylsulfonylamino)benzonitriles under base catalysis, was obtained unexpectedly. Herein, the optimal reaction conditions were explored and the results showed that high temperature and aprotic polar solvent are favorable to the ring-opening reaction. Most of the substrates studied can provide the corresponding ring-opening products in moderate to good yields after stirring in DMSO with K2CO3 at 120 degrees C for 18 h, suggesting the excellent compatibility of functional groups and the broad substrate scope of this reaction. Furthermore, the control experiments implied that 1-arylsulfonyl-3-iodoindazoles go through an E2 elimination mechanism similar to Kemp elimination.