Trifluoromethyl–containing 1,2,4-triazines. Synthesis on the base of perfluorobiacetyl and reactions with thiosemicarbazide and thiourea

Abstract Cis-, trans-isomers of 5,6-dihydroxy-5,6-bis(trifluoromethyl)- [1,2,4]-triazinan-3-thione (yield ˜69%), 5-hydroxy-5,6-bis(trifluoromethyl)-4,5-dihydro-2H- [1,2,4]-triazine-3-thione(one) (yield ˜75 − 81%) and 5,6-bis(trifluoromethyl)-1,2,4-triazine-3-amine (yield ˜60%) were synthesized by the reaction of perfluorobiacetyl with thiosemicarbazide, semicarbazide hydrochloride and aminoguanidine bicarbonate. Treating the synthesized 3-thioxo(oxo)-1,2,4-triazines with thiosemicarbazide, thiourea and hydrazine dihydrochloride gave the reduction products − 5,6-bis(trifluoromethyl)-4,5-dihydro-2H- [1,2,4]-triazine-3-thione (yield 14 − 52%) and 5,6-bis(trifluoromethyl)-4,5-dihydro-2H- [1,2,4]-triazine-3-one (yield 20–23%). The reactions with thiosemicarbazide and thiourea was accompanied by the formation of unexpected products − 5-thioxo-3a,6a-bis(trifluoromethyl)hexahydro-2H-imidazo[4,5-d]-1,3-thiazol-2-one and 5,6-bis(trifluoromethyl)-1,2,4-triazine-3-amine. The reaction of 5,6-dihydroxy-5,6-bis(trifluoromethyl)-imidazolidine-2-thione and the synthesized 3-thioxo(oxo)-1,2,4-triazines with aminoguanidine bicarbonate gives 5,6-bis(trifluoromethyl)-1,2,4-triazine-3-amine (yield ˜35 − 47%) and also can be used as a method for its preparation.