The KOH solution (30 ml, 0.1 N) was drop-wisely added to a stirred solution cold (–5˚C - 0˚C) of 3a-g (10 mmol) in methanol (20 ml). Then, the reaction mixture was stirred at same temperature for 1 h, at room temperature for 24 h and evaporated under vacuum till dryness. The obtained solid was dissolved in distilled water (50 ml), cooled in an ice bath, stirred, acidified with HCl (0.1 N) to pH ~ 2 - 3 and the precipitate was separated by filtra-tion, washed with distilled water, dried to afford the acids 4a-g (Table 2).