Trifluoromethyl-substituted heteroolefins (Schiffs bases): syntheses and chemical properties

5,5,5-trifluoro-4-trifluoromethyl-pent-3-en-2-one ( 1 ) and 5,5,5-trifluoro-4-methyl-pent-3-en-2-one ( 2 ) are reacted with a number of ring-substituted anilines to give the corresponding imines 3–16 and 17 . The preparation of 2 is accompanied by three unsaturated ketones ( 2a–c ). The bistrifluoromethylated imines 3–16 exist as a mixture of their non-separable syn and anti isomers, which were identified by 13 C, 19 F and 1 H NMR spectroscopy. Some of these imines react with 2,2-bis(trifluoromethyl)-ethylene-1,1-carbodinitrile (BTF) at room temperature to 4,4-bistrifluoro-1,4-dihydropyridinium derivatives ( 18-22 ). Two side-products, 1-amino-cyclo-pent-l-ene ( 23–27 ) and 1-imino-cyclopent-2-ene derivatives ( 28–32 ) are also obtained in these additions. Treatment of 1 with primary alkylamines yielded the anti-Michael products 33–38 . With 2-amino-benzylamine 1 formed the benzodiazepine derivative 39 .