The first step of the process for preparation of (S)-equol (1) involves Perkin reaction between 4-hydroxy phenyl acetic acid and 2,4-dihydroxy benzaldehyde in presence of an acid anhydride and a base. The most suitable acid anhydride is acetic anhydride although other acid anhydrides may also be used for the reaction. The base may be selected from a group of organic amines like triethylamine, diisopropylethylamine, trimethylamine, triisopropylamine, N-methylpiperidine and inorganic bases like sodium bicarbonate, potassium bicarbonate, potassium biphosphate, sodium biphosphate, potassium carbonate, sodium carbonate. Specifically, the base may be selected from a group of organic amines and more specifically the base may be diisopropylethylamine. The reaction is carried out at a temperature of about 100° C. to about 200° C. for a period of about 30 hours to about 60 hours. Specifically, the reaction is carried out at a temperature of about 90° C. to about 150° C. for a period of about 35 hours to about 45 hours and more specifically the reaction is carried out at a temperature of about 115° C. to about 120° C. for a period of about 38 hours to about 42 hours. After the reaction is completed, the reaction mixture is cooled from about 10° C. to about 30° C. and specifically from about 20° C. to about 25° C. and water is added. The precipitated solid is filtered and washed with water and optionally dried to provide 4-(7-acetoxy-2-oxo-2H-chromen-3-yl)phenyl acetate of formula (3).
