反应详情

The acid chloride (1.01 part) synthesized from 2,3,5-trimethyl-6-(5'-carboxypentyl)-1,4-benzoquinone (formula I-2 wherein R=H3C, n=4, in the free form) (1 part) and oxalyl chloride (5 volume parts) was dissolved in anhydrous benzene (10 volume parts) and the solution was added dropwise to a solution of salicylaldehyde (0.6 part) in pyridine (10 volume parts) at 25° C. After stirring for 2.5 hours, the reaction mixture was diluted with cold water (300 volume parts) and rendered acidic with dilute hydrochloric acid. It was then extracted twice with diethyl ether (300 volume parts). The extracts were pooled, washed with water and dried. The solvent was then distilled off under reduced pressure and the residue was subjected to column chromatography on silica gel. Elution with chloroform provided a yellow oil of 2,3,5-trimethyl-6-[5'-(o-formylphenyloxycarbonyl) pentyl]-1,4-benzoquinone (formula I-2 wherein R=H3C, n=4, in the form of o-formylphenolate) (1.3 part). To a cooled, stirred solution of this product (1.1 part) in acetone (25 volume parts) was added standard Jones reagent (2 volume parts). The solution was stirred for 100 minutes, after which it was diluted with cold water (500 volume parts), followed by extraction with ethyl acetate (500 volume parts). The extract was washed with water and dried. The solvent was then distilled off under reduced pressure and the residue was purified by column chromatography on silica gel (50 parts). The procedure provided a yellow oil of 2,3,5-trimethyl-6-[5'-(o-carboxyphenyloxycarbonyl) pentyl]-1,4-benzoquinone (formula I-2 wherein R=H3C, n=4, in the form of o-carboxyphenolate) (1.1 part).

1. extractionIt was then extracted twice with diethyl ether (300 volume parts)
2. washwashed with water
3. customdried
4. distillationThe solvent was then distilled off under reduced pressure
5. washElution with chloroform