Reactions of 2,4,4,6-Tetraaryl-4H-thiopyrans with Chlorine: An Unusual Reaction Route

Abstract

2,4,4,6-Tetraaryl-4H-thiopyrans Ia - Ig react smoothly with carbon disulfide solution of chlorine already at 0 °C yielding the corresponding 3,5-dichloro derivatives IIa - IIg. With longer reaction time and temperature raised to 20 °C, the 4H-thiopyrans Ia - Ie gave exclusively the trichloro derivatives IIIa - IIIe whereas If and Ig underwent a nonselective chlorination leading to multicomponent mixtures of products. Isolation of sulfoxides IVa and IVe from the chlorination of Ia and Ie (upon hydrolysis of the reaction mixture) allowed us to formulate the reaction mechanism for the formation of compounds type III. 1H, 13C NMR, and mass spectra of the prepared compounds are discussed in detail.