Hydrochloric Acid → (+/-)-Methyl 4-(2,5-dihydroxy-3,4,6-trimethylphenyl)-2-hydroxy-2-methylbutanoate

Participants

Reaction Steps

A solution of the crude (±)-2-cyano-4-(2,5-diacetoxy-3,4,6-trimethylphenyl)butan-2-ol prepared in Example 60 in 2000 ml. of anhydrous methanol was cooled in a dry ice-ethanol bath. When the internal temperature reached -50°, HCl gas was passed rapidly into the solution. Over the next 45 minutes, the external and internal temperatures were allowed to come to -20° and +5°, respectively. These temperatures were maintained until the solution was saturated with HCl. The clear, dark brown solution was kept at +2° overnight, stripped of solvent at reduced pressure, diluted with 2000 ml. of H2O, heated at 40° under N2 for 2.0 hours, cooled and extracted with ethyl acetate and ether. The organic solutions were washed with saturated brine, dried over Na2SO4 and stripped of solvent to give (±)-methyl 4-(2,5-dihydroxy-3,4,6-trimethylphenyl)-2-hydroxy-2-methylbutanoate as a dark green-black oil. TLC indicated that under these conditions, virtually no (±)-methyl 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylate had been formed.

Provenance & Evidence