反应详情

A mixture of 4-methoxy-2-methylbenzoic acid (10 g, 60 mmol) and dimethyl carbonate (10 ml, 120 mmol) in THF (80 ml) is added dropwise to LDA (120 ml of 2M in heptane/THF/ethylbenzene) at −78° C. The cold bath is removed, and after 4 h, water (100 ml) is added, and the resulting mixture is stirred overnight. After removal of organic solvents, the residue is acidified with c-HCl to pH 2. The resulting solid is filtered, dissolved in 1N—NaOH (80 ml), and then washed with ether (2×30 ml). The aqueous layer is acidified with c-HCl and the resulting white solid is filtered to give 12 g of 2-carboxymethyl-4-methoxy-benzoic acid. 1H NMR (DMSO) 12.3 (br s, 1H), 7.88 (d, 1H), 6.91 (d, 1H), 6.88 (s, 1H), 3.90 (s, 2H), 3.79 (s, 3H).

1. customThe cold bath is removed
2. additionwater (100 ml) is added
3. customAfter removal of organic solvents
4. filtrationThe resulting solid is filtered
5. dissolutiondissolved in 1N—NaOH (80 ml)
6. washwashed with ether (2×30 ml)
7. filtrationthe resulting white solid is filtered