Scheme 1. Synthesis scheme of ligustrazine aldehyde (3), modified ketones (7a–g) and new chalcone (8a–g & 9a–g)/oxime derivatives (10a–g & 11a–g). Reagents and conditions: (i-a) 30% H₂O₂, acetic acid, 70 °C, 8 h; (i-b) acetic anhydride, reflux, 2 h; (i-c) 20% NaOH; (ii) IBX, DMSO, room temperature, 0.5 h; (iii) K₂CO₃, Pd(PPh₃)₄, DME, 90 °C, overnight; (iv) NaOH, EtOH, room temperature; 1–6 h; (v) NH₂OH·HCl, pyridine, ethanol, anhyd., reflux, 6–8 h.