反应详情

2(1-hydroxy ethyl)-2,3,5-trimethoxy-2,5-dihydrofuran (8.4 g, 0.45 moles) in 3 ml methanol was added to 25 ml of formic acid and 1.2 ml methanol. After stirring for 5 minutes, the reaction was poured into 75 ml of water and extracted with chloroform. Concentration of the chloroform layer yielded a brown oil which solidified overnight. Recrystallization from hexane-ether yielded 4,6-dimethoxy-2-methyl-2H-pyran-3(6H)-one as white needles, mp 73°-74.5° C., NMR (CDCl3, δ) 5.75 (1H, d, J=4Hz), 5.3 (1H, d, J=4Hz), 4.62 (1H, q, J=7Hz), 3.68 (3H, s), 3.52 (3H, S), 1.2 (3H, t, J=7Hz).

1. extractionextracted with chloroform
2. customConcentration of the chloroform layer yielded a brown oil which
3. waitsolidified overnight
4. customRecrystallization from hexane-ether