Selectfluor‐Mediated N‐Methylation, N‐Methylenesulfonylmethylation and Methylenethiomethylation of Isatins in Dimethyl Sulfoxide

AbstractDimethyl sulfoxide as a reagent and solvent in Selectfluor mediated transformations of isatin is reported. The transformations include N‐methylation and N‐methylenesulfonylmethylation of isatin at 100 °C whereas N‐methylenethiomethylation was observed at 140 °C in addition to N‐methylation and N‐methylenesulfonylmethylation of isatins. Electron withdrawing and releasing substituents on isatin were tolerated. Interestingly, dual (N‐ and C−)methylenethiomethylation was observed in case of 7‐Bromo‐ and 7‐Iodo isatins at 140 °C. This protocol efficiently afforded various isatin analogs using DMSO/Selectfluor system.