Trifluoromethyl-substituted heteroolefins (Schiff's bases): Syntheses and chemical properties

Article abstract of DOI:10.1016/S0022-1139(97)00017-1

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 ¹³C, ¹⁹F and ¹H NMR spectroscopy. Some of these imines react with 2,2-bis(trifluorornethyl)-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-1-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. Elsevier Science S.A.