QUINONE DERIVATIVES

A method for producing a compound of formula: wherein each R4 is lower alkyl having 1 to 4 carbon atoms or lower alkoxy having 1 to 4 carbon atoms, or two R4's taken together represent -CH=CH-CH=CH-; n is an integer of 0 to 20 and when n is 1 to 20, A is a group of -CH2-, or -CO- and B is hydroxymethyl, acyloxymethyl having 2 to 11 carbon atoms, esterified or unesterified carboxyl having 1 to 5 carbon atoms, lower alkoxymethyl having 2 to 5 carbon atoms, silyloxymethyl having 4 to 7 carbon atoms or acetalmethyl having 3 to 8 carbon atoms; when n is 0, -A?CH2)n-B is (wherein ? is an integer of 0 to 12) and B is hydrogen, which comprises oxidizing a compound of formula: wherein X1 or X2 is hydroxyl or amino, with the other being hydrogen, an esterified hydroxyl group having 1 to 8 carbon atoms or etherified hydroxyl group having 2 to 8 carbon atoms; the other symbols are as defined above, with oxygen or air in the presence of a transition metal complex compound. The compounds are medicine effective against heart failure, periodontal disease etc. The novel method gives increased yield and purity of the compounds and is safer for commercial production.