Synthesis, molecular and crystal structures of new amino enones containing trifluoromethyl and 3- or 4-pyridyl substituents

The reaction of lithium (Z)-1,1,1-trifluoro-4-oxo-4-(pyridin-3-yl)- or (Z)-1,1,1-trifluoro-4-oxo-4-(4-pyridin-4-yl)but-2-en-2-olate with ammonium acetate in glacial AcOH afforded new amino enones containing an amino group geminal to the fluoroalkyl substituent, (Z)-3-amino-4,4,4-trifluoro-1-(pyridin-3-yl)- and (Z)-3-amino-4,4,4-trifluoro-1-(pyridin-4-yl)but-2-en-1-one, respectively. On heating in AcOH under reflux, (Z)-3-amino-4,4,4-trifluoro-1-(pyridin-3-yl)but-2-en-1-one undergoes a series of transformations, giving 7-trifluoromethyl-1,6-naphthyridine as one of the products. A comparative study of the physicochemical parameters and the crystal structures of amino enones containing a CF₃ group and 2-, 3-, or 4-pyridyl substituents was performed.