反应详情

A mixture of 2,4-dihydroxy acetophenone (2.0 g, 13.2 mmol) and oven-dried potassium carbonate (4.0 g, 30.0 mmol) in dry acetone (30 mL) was stirred for 10 min. Methoxymethylene chloride (MOMCl) (1.62 mL, 17.2 mmol) was added dropwise to the reaction mixture and the mixture was stirred at room temperature for 24 h. Solvent was evaporated under reduced pressure and water (25 mL) was added. The mixture was extracted with chloroform (3×100 mL) and the organic phase was dried over Na2SO4 and evaporated under reduced pressure. The residue was column chromatographed on silica gel eluting with 20% ethyl acetate in hexanes to afford acetophenone 6a (2.2 g, 87% yield) as a very low melting solid. Rf=0.51 (25% EtOAc-hexanes): mp 38-39° C. IR (KBr) 2959, 2829, 1632, 1579, 1504, 1367, 1262, 1142 cm−1; 1H NMR (300 MHz, CDCl3) δ 7.59 (d, J=8.7 Hz, 1H), 6.51 (m, 2H), 5.15 (s, 2H), 3.42 (s, 3H), 2.51 (s, 3H); 13C NMR (75 MHz, CDCl3) δ 202.6, 164.7, 163.4, 132.3, 114.6, 108.0, 103.6, 93.8, 56.2, 26.1; EIMS (m/z, rel intensity) 196 (M+, 100), 181 (6), 164 (9), 151 (32), 137 (24).

1. stirringthe mixture was stirred at room temperature for 24 h
2. customSolvent was evaporated under reduced pressure and water (25 mL)
3. additionwas added
4. extractionThe mixture was extracted with chloroform (3×100 mL)
5. dry with materialthe organic phase was dried over Na2SO4
6. customevaporated under reduced pressure
7. customchromatographed on silica gel eluting with 20% ethyl acetate in hexanes