反应详情

1-(3,4,5-trimethoxyphenyl)-1,2-ethanedithiol (32) (FIG. 26) (0.500 g, 1.92 mmole), 5-iodovanillin (0.411 g, 1.48 mmole), pyridinium para-toluenesulfonate (0.193 g, 0.769 mmole) and 50 ml dry benzene were refluxed under an argon atmosphere with Dean-Stark removal of the benzene-water azeotrope for 12 hours. The benzene was removed in vacuo, and the remaining oil redissolved in dichloromethane. The organic layer was washed with 3×30 ml H2O and was dried over MgSO4, and evaporated in vacuo to an oil which was purified by flash column chromatography with 2:1 hex/ethyl acetate as eluent. The product mixture contains a 1.0/1.3 cis/trans ratio (0.578 g, 75%) after one crystallization from methanol. The trans isomer (50 mg) was isolated after one additional crytallization from ethanol.

1. customThe benzene was removed in vacuo
2. dissolutionthe remaining oil redissolved in dichloromethane
3. washThe organic layer was washed with 3×30 ml H2O
4. dry with materialwas dried over MgSO4
5. customevaporated in vacuo to an oil which
6. customwas purified by flash column chromatography with 2:1 hex/ethyl acetate as eluent
7. customafter one crystallization from methanol
8. customThe trans isomer (50 mg) was isolated after one additional crytallization from ethanol