PURPOSE: To obtain in high yield a compound, which is useful as a synthetic intermediate of a therapeutic agent for infantile prothrombinemia and hemostatic vitamin by oxidizing a specific naphthoquinone with a specific compound without use of heavy metal.
CONSTITUTION: 2-Methyl-4a,5,8,8a-tetrahydro-1,4-naphthoquinone of formula I is oxidized with at least one selected from air, 2,3-dichloro-5,6-dicyano-1,4- benzoquinone and chloranyl in the presence of manganese dioxide, lithium chloride, cupric chloride dihydrate to give the object compound of formula II. The compound for formula I is obtained, for example, by Diels-Alder reaction between 1,3-butadiene and a 2-methyl-1,4-benzoquinone resulting from oxidation of 0-toluidinie of formula III.
TSUJII MASAHIKO
HAMAMURA KICHISABURO
SEKI CHIAKI
KONISHI YUSUKE
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