Isomerization of erythro-1,2-Diaryl-1,2-ethanediol to threo-1,2-Diaryl-1,2-ethanediol Promoted by Potassium t-Butoxide

Masatoshi KAWASHIMA*, Minoru NAKAYAMA and Akiko MIYAKAWA

Kankyo Kagaku Center Co., Ltd.; Yokohama-shi 236-8605 Japan

Isomerization of erythro-1,2-diphenyl-1,2-ethanediol(1a) into threo-1a was successfully achieved by treatment with 2 molar amounts of potassium t-butoxide in refluxing THF for 2 h. Monoesters or diester of erythro-1a with pivalic acid or benzoic acid were also isomerized into the corresponding threo-isomers, when treated with 4 molar amounts of potassium t-butoxide even at room temperature. erythro/threo-Isomerization of 1,2-bis(4-methoxyphenyl)-1,2-ethanediol and 1,2-bis(4-methyl- phenyl)-1,2-ethanediol proceeded under the similar conditions but failed for isomerization of 1,2-acenaphthenediol.

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