PURPOSE: To obtain a derivative which is important as a hematostasis-activating vitamin without formation of its geometric isomer, in high yield and in an industrial scale by the reverse Diels-Alder reaction of a specific anthraquinone derivative.
CONSTITUTION: 1,4,4a,5,8,9-Hexahydro-4aα-alkenyl-1α,4α-methanoanthraquinone of formula I (R1, R2 are H, methyl; n is 0, 1 to 9; formula II is a single bond or a double bond) is subjected to reverse Diels-Alder reaction in the presence of a dehydrogenating agent or an oxidizing agent to give the object derivative of formula III. A compound which is obtained by reacting, in the presence of a base, an allyl derivative of formula VI with a derivative of formula V which is a product from Dilels-Alder reaction of a derivative of formula IV with cyclopentadiene is preferably used as the derivative of formula I. Further, the dehydrogenating agent is preferably 2,3-dichloro-5,6-dicyano-1,4-benzoquinone or p- or o-chloranyl, while the oxidizing agent is manganese dioxide.
SEKI CHIAKI
KONISHI YUSUKE