FORMATION OF UREA, ISOUREA, AND TRIAZINE DERIVATIVES FROM DIISOPROPYLCYANAMIDE WITH TRIFLUOROACETIC-ANHYDRIDE AND TRIFLUOROMETHANESULFONIC ANHYDRIDE - THERMAL-INSTABILITY OF UREA AND ISOUREA DERIVATIVES

Diisopropylcyanamide reacts exothermically with trifluoroacetic anhydr ide to give 2, an equilibrium mixture, in C6D6 solution, of 1:1 adduct s, N,N-diisopropyl-N',O-bis(trifluoroacetyl), 2a (10%), and N,N-diisop ropyl-N',N'-bis(trifluoroacetyl)urea, 2c (90%), at 27 degrees C. Compo und 2c is a colorless solid, mp 49-51 degrees C. Thermolysis of 2, at 117 degrees C, shows first-order kinetics with the intital products be ing trifluoroacetonitrile, 4, and diisopropylcarbamic trifluoroacetic mixed anhydride, 3. Trifluoroacetonitrile trimerizes to 2,4,6-tris(tri fluoromethyl)-1,3,5-triazine, and 3 is thermally labile giving diisopr opyltrifluoroacetamide and CO2. In the thermolysis reaction 4 reacts w ith 2a to give a small amount of toxy)-2,6-bis(trifluoromethyl)-4H-1,3 ,5-oxadiazine 7. A related compound, ino)-2,6-bis(trifluoromethyl)-4H- 1,3-5-oxadiazine, 8, is formed from 7 and 2c going through a concentra tion maximum at 4000 s in the kinetic run. Compound 8 thermolytically dissociates to generate 4 and tetraisopropylurea. Compound 2 is a tirf luoroacetylating agent with methanol giving methyl trifluoroacetate in 97% yield. Accompanying this reaction is a methanol displacement of d iisopropylamine giving a 1.7% yield of methyl-N-(trifluoroacetyl)ureth ane. Diisopropylcyanamide also reacts exothermically with trifluoromet hanesulfonic anhydride to give ropylamino)-1-(trifluoromethanesulfonyl )triazinium trifluoromethanesulfonate, 15, in 96% yield. X-ray crystal lographic structure drawing of 15 shows N1 (attached to CF3SO2) is pyr amidal while N2, N4, and N6 (all diisopropylamino nitrogens) are sp(2) -planar. A small amount of N-diisopropyl-N'-(trifluoromethanesulfonyl) isourea was also recovered, produced by the reaction of the initially formed intermediate, opropyl-N',O-bis(trifluoromethanesulfonyl)isourea , with ethanol contaminant in absolute ethyl ether solvent. Treatment of 15 with methanol, in the presence of K2CO3, gave a 90% yield of oro methanesulfonyl)-4-methoxy-1,4-dihydrotriazine.