Chemistry of 4-dicyanomethylene-1,2,6-thiadiazines

摘要: The chlorine atoms in 3,5-dichloro-4-dicyanomethylene-1,2,6-thiadiazine 1 are readily displaced by thiophenols the presence of Hunig’s base, first at −78 °C and second 20 °C to give orange mono- bis-arylthio derivatives high yield (Table 1). Similarly secondary amines red blue bis-amino compounds 2); piperidine, for example, gives former latter −30 °C. A low limit reactivity is reached with diisopropylamine which mono derivative only, (30%). Reactions ammonia primary complex since formed can cyclise onto adjacent cyano group, aniline giving only a pyrrolo[2,3-c][1,2,6]thiadiazine 8. 4-dicyanomethylene compound more reactive than known 4-oxo analogue 2, but suffer added complications group cyclisation hydrolysis dicyanomethylene keto group. 3,5-Dimorpholino-4-dicyanomethylene-1,2,6-thiadiazine 7c oxidized sulfoxide 9 MCPBA or N2O4, reverts triphenylphosphine–tetrachloromethane, all yield. Thiadiazine undergoes reaction DMSO three furo[2,3-c][1,2,6]thiadiazines 10, 11 (tentatively) 12 could arise from initial product 13 displacement DMSO, type rearrangements. Mechanisms proposed new reactions.