An efficient method for the synthesis
of [1,4]thiazino[4,3-a]indole derivatives using sodium
chlorodifluoroacetate
(ClCF2CO2Na) and elemental sulfur as the difluoromethylthiolating
reagent system has been developed. Three-component reactions of 2′-aminochalcones,
sulfur, and ClCF2CO2Na under basic conditions
using TEMPO as the oxidant afforded [1,4]thiazino[4,3-a]indol-10-ones containing a difluoromethyl thioether moiety in good
yields. Four bonds including one C–N, two C–S, and one
C–C bonds are selectively formed in the sequential transformation
process.