Sumitomo Chemical Company, Limited

Fukashi Horiuchi

Nobushige Itaya

Takeaki Umemura

Masanao Matsui

Akio Higo

Hajime Hirai

Toshiko Honda

A novel process for preparing cis-chrysanthemic acid comprising (1) hydrolysis of trans-.delta.-halogenodihydrochrysanthemic acid or ester thereof under neutrally kept condition with an alkaline earth metal carbonate, (2) conversion of the obtained trans-.delta.-hydroxydihydrochrysanthemic acid ester into a mixture of cis-chrysanthemic acid and iso-cis-chrysanthemic acid by reacting with a strong base, and (3) separation of the cis-chrysanthemic acid from the mixture by selective conversion of the iso-cis-chrysanthemic acid with water in the presence of an acid catalyst into cis-dihydrochrysanthemolactone, followed by separation of the cis-chrysanthemic acid from the lactone with a caustic alkali and an acid. The present process is very useful for converting (-)-trans-chrysanthemic acid which is obtained, as a main remainder of racemic chrysanthemic acid prepared industrially, after (+)-trans-chrysanthemic acid was used for preparation of (+)-trans-chrysanthemic acid ester having a high insecticidal activity, into (+)-cis-chrysanthemic acid which is industrially valuable for preparation of insecticides.

Process for preparing cis-chrysanthemic acid

A process is provided for preparing racemic allethrolone which comprises reacting (-) allethrolone with phosphorus chloride compounds in the presence of a Lewis acid, and hydrolyzing the racemic 4-chloro-allethrone thus obtained.

Racemization of optically active allethrolone

The present invention relates to a process for preparing allethrolone which involves hydrolyzing 2-allyl-4-hydroxy-3-methyl-2-cyclopentenone acid phthalate represented by the formula ##SPC1## In water or an aqueous solvent with or without a base of less than a small excess of the equivalent.

Preparation of optically active allethrorone via allethronyl acid

Optically active allethronyl acid phthalate is prepared by reacting (.+-.)-allethronyl acid phthalate of the formula ##SPC1## With an optically active amine from the group of .alpha.-phenylethylamine of the formula, ##SPC2## .alpha.-phenyl-.beta.-p-tolylethylamine of the formula ##SPC3## Threo-2-dimethylamino-1-(p-nitrophenyl)-1,3-propanediol of the formula ##SPC4## And naphthylethylamine of the formula ##SPC5## To form diastereomeric salts thereof, and decomposing the resolved salt to obtain the optically active allethronyl acid phthalate.

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Kawanishi, Japan

Fukashi Horiuchi