4-(3,4-DIMETHOXYPHENYL)-2,2-DIMETHYL-4-OXOBUTYRIC ACID synthesis

Yield:-

Reaction Conditions:

Stage #1: 3,4-dimethoxyphenylmagnesium bromidewith 2,2-dimethylsuccinic anhydride in tetrahydrofuran at 0 - 20; for 1 h;
Stage #2: with water;ammonium chloride in tetrahydrofuran;

Steps:

A.1

A1. 4-(3, 4-dimethoxyphenvlS2, 2-dimethvl-4-oxo-butvric acid Under an atmosphere of dry nitrogen a grignard solution, prepared from 43.4 g 3, 4-dimethoxybromo- benzene and 6.1 g magnesium in 200 ml of tetrahydrofuran, is added dropwise to a solution of 20.5 g 3,3- dimethyl-dihydro-furan-2, 5-dione in 200 mi of tetrahydrofuran cooled in an ice-bath. The reaction mixture is stirred for an additional hour at RT. 100 ml of a 20% ammonium chloride solution is added and the water layer is extracted twice with 75 ml of ethyl acetate. The combined organic layers are washed twice with 100 ml of half saturated brine and extracted with 3 x 100 mi 1 M sodium hydroxide solution. The aqueous layers are washed with 75 ml of ethyl acetate, acidified with concentrated hydrochloric acid and extracted 3 times with 100 ml of dichloromethane. The organic layers are dried over magnesium sulfate, filtered and concentrated in vacuo. The oily residue is crystallized from ethyl acetate/petroleum ether (60-80 °C). M. p. 114-116°C.

References:

WO2005/75456,2005,A1 Location in patent:Page/Page column 26