PURPOSE: To obtain the titled compound useful as a raw material for hypotensor, etc., by using an organic acid repeatedly without requiring concentration, by dripping hydrogen peroxide to a mixture of an indene and an organic acid to react them, extracting the formed oxide with a water-insoluble organic solvent and heating the extracted solution with a mineral acid.
CONSTITUTION: An organic acid is added to an indene shown by formula I (R is lower alkyl) to give a mixture. Hydrogen peroxide is dripped to the mixture, which is oxidized at 0W60°C, preferably 30W40°C. After the reaction, the reaction mixture is extracted with a water-insoluble organic solvent (preferably dichloroethane, etc.) and the prepared extracted solution is reacted with a mineral acid such as sulfuric acid, etc., preferably under heating at 80W90°C for 5W2 hours to give a compound shown by formula II. Usually 10W90 wt%, preferably 20W60 wt% aqueous solution of hydrogen peroxide is used as the hydrogen peroxide in the reaction and the amount of it is 0.5W3 equivalents, preferably 1.1W1.5 equivalent based on the indene of the raw material.
SASAKI TOSHIKI
YANAI HIROSHI
