2,4,6-Triaryl-dihydro-1,3,5-dithiazines reacted with electrophilicreagents such as p-TsOH·H2O, CF3COOH, HCl, and BF3·OEt2 under reflux in CH3CN to afford α-2,4,6-triaryl-1,3,5-trithianes and β-isomers (3a-d) in good yields. Reactions with I2 gave selectively 3a-d in high yields, while with ICl or IBr gave 3a-d and p-substituted benzylideneamine·HY.