反应详情

To a stirred mixture of sodium borate decahydrate (borax, 80 g) in H2O (1 L) was added methyl gallate (3, 15.0 g, 82 mmol) at rt. After stirring for 1 h, dimethyl sulfate (30 ml, 317 mmol) and NaOH (50 ml, 6.5 M) were added dropwise simultaneously via separate addition funnels over the course of 1 h. After stirring an additional 12 h, the methylation was terminated with H2SO4, (65 ml, conc.) and stirring continued an additional h. The product was removed by extraction with DCM (5×500 ml, each time stirring the solution for 20 min). The combined DCM extracts were washed with brine (300 ml), dried, concentrated in vacuo, and the residue crystallized from methanol-benzene to afford methyl ether 4 (13.7 g, 85%) as a light tan solid, mp 110–111° C., (lit. mp 110–111° C., Pettit and Singh, 1987); 1H-NMR (300 MHz): 3.89 (3H, s, —OCH3), 3.94 (3H, s, —OCH3), 5.40 (2H, bs, —OH), 5.80 (2H, bs, —OH), 7.22 (1H, d, J=1.8 Hz, ArH), 7.35 (1H, d, J=1.8 Hz, ArH).

1. customvia separate
2. additionaddition funnels over the course of 1 h
3. stirringAfter stirring an additional 12 h
4. customthe methylation was terminated with H2SO4, (65 ml, conc.)
5. stirringstirring
6. customThe product was removed by extraction with DCM (5×500 ml
7. stirringeach time stirring the solution for 20 min)
8. washThe combined DCM extracts were washed with brine (300 ml)
9. customdried
10. concentrationconcentrated in vacuo
11. customthe residue crystallized from methanol-benzene