Scheme 21. Synthesis of the thiazole/thiazolidinone-pyrazoline hybrids 83a, b, 84 and 85a, b. Reagents and conditions: (i) ethyl 2-chloroacetoacetate, Abs. EtOH, reflux, 10 h; (ii) NaOH, MeOH, reflux 4–6 h then neutralized with Conc HCl; (iii) bromoacetic acid, abs. EtOH, anhydrous CH3COONa, reflux, 5h; (iv) 2-(2-formylphenoxy)acetic acid, glacial acetic acid, anhydrous sod. Acetate, reflux, 12 h.
