Patent ID: 6544390
Filing Date: 2003-04-08
Classification: C07C

Abstract:
A microwave assisted rapid and economical process for the preparation of substituted phenylaldehyde of general formula (I) from substituted trans and toxic cis-phenyipropene, thereby commercially utilizing the toxic cis-isomer of phenylpropene, whereinR1&boxH;â€”CHO, R2, R3, R4, R5, R6 are independently selected from i) a hydrogen atom; ii) an alkoxy group wherein at least two of R2, R3, R4, R5, R6 being a hydrogen atom; or an alkoxy group but one of R2, R3, R4, R5, R6 being a methylenedioxy group in combination with either a hydroxyl group, an alkoxy group, an alkyl group having at least one carbon atom, an aryl group and a hydrogen atom or an alkoxy group but one of R2, R3, R4, R5, R6 being a hydroxyl group in combination with either a methylenedioxy group, a hydroxyl group, an alkoxy group, an alkyl group having at least one carbon atom, an aryl group or a hydrogen atom; iii) a methylenedioxy group wherein at least three of R2, R3, R4, R5, R6 being in combination with either an alkoxy group, a hydroxy group, an alkyl group having at least one carbon atom, an aryl group or a hydrogen atom; iv) a hydroxyl group at least one of R2, R3, R4, R5, R6 being a hydrogen atom in combination with either an alkoxy group, a hydroxyl group, a methylenedioxy group, an alkyl group having at least one carbon atom, an aryl group or a hydrogen atom; v) a protected hydroxyl group wherein at least one of R2, R3, R4, R5, R6 being a hydrogen atom in combination with either an alkoxy, a hydroxyl group, a methylenedioxy group, an alkyl group having one or more carbon atom, an aryl group or a hydrogen atom; said process comprising steps of: a) oxidizing said substituted phenyipropene in the presence of an oxidizing agent and optionally with a co-catalyst in a solvent at a mole ratio of 1:1 to 1:12 for a period ranging from 20 seconds to 20 minutes under microwave irradiation, b) filtering the reaction mixture of step (a) and washing the residue with an organic solvent, c) washing the organic solution of step (b) with aqueous sodium bisulphite or sodium thiosulphate followed by brine and water, d) drying the organic layer of step (c) over anhydrous sodium sulphate, filtering and evaporating to dryness to remove completely the solvent to obtain a residue, and e) purifying the residue of step (d) by recrystallization or column chromatography to obtain the required substituted phenylaldehye of general formula (I).