Benzene → trans 2-(4-Hydroxy-5-iodo-3-methoxyphenyl)-4-(3,4,5-trimethoxyphenyl)-1,3-dithiolane

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Reaction Steps

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.

Provenance & Evidence