An efficient method for the preparation of 1,3,4-thiadiazine derivatives has been reported. With 2,5-dihydroxy-1,4-dithiane and α-chloroindole containing different substituents, 13 compounds were synthesized. The yields of the compounds were above 82% except (E)-4-phenyl-2-styryl-5,6-dihydro-4H-1,3,4-thiadiazin-5-ol (3m). Furthermore, the proposed reaction mechanism was discussed. The developed method features simple operation, mild reaction condition, environmentally friendly, high yield and a broad range of substrate applicability. It provides a new way for the synthesis of 1,3,4-thiadiazine derivatives.

Key words: α-chloroindole, 1,3,4-thiadiazine, synthesis