反应详情

To a solution of 3,4-dihydroxybenzoic acid ethyl ester (2.0 g, 11 mmol) in acetone (450 l) were added potassium carbonate (2.28 g, 16.5 mmol) and isopropylamide (1.03 ml, 11 mmol), and the resultant mixture was stirred at room temperature for 2 days. The reaction mixture was poured into chilled water and extracted with ethyl acetate under acidic conditions. The organic layer was concentrated, and the residue was chromatographed On a silica gel column to give a mixture (617 mg) of 3-hydroxy-4-isopropyloxybenzoic acid ethyl ester and its position isomer, 4-hydroxy-3-isopropyloxybenzoic acid ethyl ester (6:1). There was observed NOE of protons at 1'-position of the isopropyl group and 5-position. The reaction was effected using this mixture (617 mg) in the same manner as in Reference Example 18, and the resultant product was recrystallized from hexane to give the titled compound (370 mg, yield 12%).

1. additionThe reaction mixture was poured
2. extractionextracted with ethyl acetate under acidic conditions
3. concentrationThe organic layer was concentrated
4. customthe residue was chromatographed On a silica gel column