An efficient route for the synthesis of some monoazo disperse dyes derived from nicotinic acid derivatives

Ethyl 2-amino-3-cyano-4-phenylnicotinates (8), could be readily synthesized via reacting ethyl propiolate with benzylidenemalononitrile in the presence of L-proline as a catalyst and subsequent rearrangement of the so formed 2-aminopyran (7), with acetic acid in the presence of ammonium acetate. A series of 2-amino and 2-hydroxyarylazonicotinates monoazo disperse dyes (12a-c), were prepared in a good yields via condensation of arylhydrazonals (11a-c), with active methylene nitriles. The compound 9 was also characterized by single crystal X-ray diffraction studies. Crystal data for compound 9, C15H18O6 (M = 294.29): hexagonal, space group P65 (no. 170), a = 11.3311(5) Å, c = 19.5375(10) Å, V = 2172.42(18) Å3, Z = 6, T = 296(2) K, μ(MoKα) = 0.879 mm-1, Dcalc = 1.350 g/mm3, 4546 reflections measured (9.02 ≤ 2Θ ≤ 132.96), 2271 unique (Rint = 0.0921) which were used in all calculations. The final R1 was 0.0686 (>2σ(I)) and wR2 was 0.1691 (all data)