Benzene → 3-(4,6-Dimethoxy-2-hydroxyphenyl)-2-methyl-2-propenic acid ethyl ester

Participants

Reaction Steps

4,6-Dimethoxysalicylaldehyde (30.0 g, 165 mmol; Aldrich Inc.) and carboxyethylidene-triphosphorane (60.0 g, 166 mmol; Aldrich Inc.) were stirred in 300 ml of anhydrous benzene at room temperature overnight under a nitrogen atmosphere and the reaction was allowed to complete, during which period the reaction was conducted in a dark room. Then, the benzene solvent was removed in vacuo to give a crudely purified product. The resulting crude product was crudely purified by silica gel column chromatography (hexane/ethyl acetate 1:1 as a developing solvent) to give a mixture of cis- and trans-isomers. The thus obtained mixture was purified by column chromatography using aminopropyl-modified silica gel (300 g of NHDM-1020 silica gel available from Fuji Silicia Chemicals Co. Ltd; n-hexane/ethyl acetate 2:1 which elutes only the cis-isomer and chloroform/methanol 4:1 which elutes only the trans-isomer) to give 35.4 g of the desired product in 81% yield.

Provenance & Evidence