反应详情

Crude 1-(2,5-dimethoxy-3,4,6-trimethylphenyl)but-3-en-1-ol (9.8 g) in 10 mL CH2Cl2 was added slowly, dropwise to a rapidly stirred, biphasic solution of TFA (10.5 mL, 153 mmol, 5 equiv.) and Et3SiH (6.3 mL, 1.3 equiv). The exothermic reaction was cooled in a room temperature water bath until addition was complete and the reaction stirred for and additional 2 h at room temperature. The brown solution was concentrated via rotovap, azeotroped 3×50 mL MeOH and 3×50 mL heptane and remainder taken up into 100 mL 5% EtOAc/heptane. The organic layer was washed 1×100 mL water, 1×50 mL saturated aqueous NaCl, filtered to remove particulates and dried over Na2SO4. Flash chromatography yielded 5.08 g of 1-(but-3-enyl)-2,5-dimethoxy-3,4,6-trimethylbenzene as a pale yellow oil which solidified upon standing to an off white wax. 1H NMR (400 MHz, CDCl3) δ=5.93 (m, 1 H), 5.08 (m, 1 H), 4.99 (m, 1 H), 3.68 (s, 3 H), 3.65 (s, 3 H), 2.70 (m, 2 H), 2.24 (m, 5 H), 2.18 (s, 6 H) ppm.

1. customThe exothermic reaction
2. additionuntil addition
3. stirringthe reaction stirred for and additional 2 h at room temperature
4. concentrationThe brown solution was concentrated via rotovap
5. customazeotroped 3×50 mL MeOH and 3×50 mL heptane and remainder
6. washThe organic layer was washed 1×100 mL water, 1×50 mL saturated aqueous NaCl
7. filtrationfiltered
8. customto remove particulates
9. dry with materialdried over Na2SO4