Process for the preparation of a quinone derivative

A process for the preparation of a quinone compound represented by the following formula (III):

• ##STR41## wherein R.sup.1 and R.sup.2 are identical with or different from each other and represent a lower alkyl or lower alkoxy group, or together form an aromatic ring, R.sup.3 represents a lower alkyl group, n is 0 or an integer of 1 to 9, and a linkage ------ is a single or double bond, which comprises reacting a 1,4,4a,8a-tetrahydro-1.alpha.,4.alpha.-methanonaphthalene-5,8-dione compound represented by the following formula (IV):
• ##STR42## wherein R.sup.1 and R.sup.2 have the same meaning as defined above, with an allyl compound represented by the following formula (V):
• ##STR43## wherein L represents a halogen atom, alkylsulfonyl group or arylsulfonyl group, and n and a linkage ------ have the same meaning as defined above, in the presence of a base to form a 1,4,4a,8a-tetrahydro-4a.alpha.-alkenyl-1.alpha.,4.alpha.-methanonaphthalen e-5,8-dione compound represented by the following formula (I):
• ##STR44## wherein R.sup.1, R.sup.2, n and a linkage ------ have the sane meaning as defined above, reacting the thus-formed compound (I) with an alkyl halide represented by the following formula:
• R.sup.3 X
• wherein R.sup.3 has the same meaning as defined above, and X represents a halogen atom, in the presence of a base to form a 1,4,4a,8a-tetrahydro-4a.alpha.-alkenyl-8a.alpha.-alkyl-1.alpha.,4.alpha.-m ethanonaphthalene-5,8-dione compound represented by the following formula (II):
• ##STR45## wherein R.sup.1, R.sup.2, R.sup.3, n and a linkage ------ have the same meaning as defined above, and then subjecting the thus-formed compound (II) to a Retro Dieis-Alder reaction to form the compound of formula (III).