A process for the preparation of 2-substituted-2-(6-(substituted)-7-methylbenzo[d][1,3]dioxol-4-yl)acetic acid derivatives of formula-I, wherein R 1 is a O-protecting group which is methoxymethyl, ethoxymethyl, trialkylsilyl, arylmethyl, tetrahydropyran-2-yl, or allyl; X is hydroxyl, halogen, mesylate, triflate, tosylate, or acetate; Y is oxygen atom, NH or sulfur atom; R 2 is C 1 -C 6 alkyl which comprises: (i) Reaction of 2,4-dihydroxy-3-methylbenzaldehyde with an etherification reagent in the presence of a base (or acid in case of tetrahydropyran-2-yl protection) and a solvent at 0-100°C to get the mono-protected derivative of formula-XII, Wherein R 1 = methoxymethyl, ethoxymethyl, trialkylsilyl, tetrahydropyran-2-yl, allyl, arylmethyl (ii) Oxidation of compound of formula-XII with an oxidizing agent in the presence of a base and a solvent at pH 7-14 to get the dihydroxy compound of formula-XIII, Wherein R 1 = methoxymethyl, ethoxymethyl, trialkylsilyl, arylmethyl, tetrahydropyran-2-yl, allyl; (iii) Reaction of dihydroxy compound of formula-XIII with a base and an aldehyde compound of formula-XIV, Wherein Y and R 2 are as defined above in the presence of a solvent at 0-100°C to get the compound of formula-XV, Wherein R 1, Y, and R 2 are as defined above (iv) Reaction of dihydroxy compound of formula-XV with a dihalomethane in the presence of a base and a solvent at 15-120°C to get the methylenedioxy derivative of formula-XVI Wherein R 1, Y, and R 2 are as defined above (v) Conversion of hydroxyl group to X wherein X is as defined above using a suitable reagent, which suitable reagent is thionyl chloride, methanesulfonyl chloride, triflic anhydride, acetyl chloride, acetic anhydride, p-toluenesulfonyl chloride, benzenesulfonyl chloride, carbon tetrachloride/triphenylphosphine, or carbon tetrabromide/triphenylphosphine, in the presence of a base at -78 to 40°C to get the compound of formula-I Wherein R 1, R 2, X, and Y are as defined above. (i) Reaction of 2,4-dihydroxy-3-methylbenzaldehyde with an etherification reagent in the presence of a base (or acid in case of tetrahydropyran-2-yl protection) and a solvent at 0-100°C to get the mono-protected derivative of formula-XII, Wherein R 1 = methoxymethyl, ethoxymethyl, trialkylsilyl, tetrahydropyran-2-yl, allyl, arylmethyl (ii) Oxidation of compound of formula-XII with an oxidizing agent in the presence of a base and a solvent at pH 7-14 to get the dihydroxy compound of formula-XIII, Wherein R 1 = methoxymethyl, ethoxymethyl, trialkylsilyl, arylmethyl, tetrahydropyran-2-yl, allyl; (iii) Reaction of dihydroxy compound of formula-XIII with a base and an aldehyde compound of formula-XIV, Wherein Y and R 2 are as defined above in the presence of a solvent at 0-100°C to get the compound of formula-XV, Wherein R 1, Y, and R 2 are as defined above (iv) Reaction of dihydroxy compound of formula-XV with a dihalomethane in the presence of a base and a solvent at 15-120°C to get the methylenedioxy derivative of formula-XVI Wherein R 1, Y, and R 2 are as defined above (v) Conversion of hydroxyl group to X wherein X is as defined above using a suitable reagent, which suitable reagent is thionyl chloride, methanesulfonyl chloride, triflic anhydride, acetyl chloride, acetic anhydride, p-toluenesulfonyl chloride, benzenesulfonyl chloride, carbon tetrachloride/triphenylphosphine, or carbon tetrabromide/triphenylphosphine, in the presence of a base at -78 to 40°C to get the compound of formula-I Wherein R 1, R 2, X, and Y are as defined above.