反应详情

A mixture of 4.7 g of ethyl 7-hydroxychromone-2-carboxylate and 20 ml of 1-chloro-2,3-epoxypropane is heated at an external temperature of 100° C. for 8 hours in the presence of 0.2 ml of piperidine. The mixture is evaporated under reduced pressure and the residue is taken up with 15 ml of ethyl acetate. After filtration, the solution is evaporated under reduced pressure, the residue is taken up with 30 ml of chloroform and 10 ml of N hydrochloric acid, concentrated and stirred for one hour. The organic layer is washed with water, dried on anhydrous sodium sulfate and evaporated. The residue, crystallized from ethanol, gives 4 g of ethyl 7-(3-chloro-2-hydroxypropoxy)chromone-2-carboxylate. An amount of 1.65 g of the product thus obtained is dissolved in 40 mg of methylene chloride and to the solution thus obtained there is added 0.2 g of hexadecyltributylphosphonium bromide. To the organic solution there is added a solution of CH3SNa in 20 ml of water. The mixture is stirred for two hours at the room temperature, the aqueous layer is separated and acidified with N hydrochloric acid. The precipitate which forms, consisting of 7-(2-hydroxy-3-methylthiopropoxy)chromone2-carboxylic acid, is filtered and dried; m.p. 200°-202° C.

1. customThe mixture is evaporated under reduced pressure
2. filtrationAfter filtration
3. customthe solution is evaporated under reduced pressure
4. concentrationconcentrated
5. washThe organic layer is washed with water
6. dry with materialdried on anhydrous sodium sulfate
7. customevaporated
8. customThe residue, crystallized from ethanol