of 1 2 3 4 9 10 hexahydro 5 8 dimethoxy 2 3 dimethylene 1 4 epoxyanthracene 1 77 g 7 8 mmol of 2 3 dichloro 5 6 dicyano 1 4 benzoquinone and 30 ml of benzene was stirred at room temperature under nitrogen for 30 minutes the precipitate formed was filtered off and washed with benzene the benzene solution was washed with two 30 ml portions of saturated aqueous sodium hydrogen sulphite solution and two 30 ml portions of water dried over sodium sulphate and concentrated to dryness by recrystallization from diethyl ether tetrahydrofuran methylene chloride 4 1 2 there were obtained 1 95 g 98 of 1 2 3 4 tetrahydro 5 8 dimethoxy 2 3 dimethylene 1 4 epoxyanthracene of melting point 205 u00b0 206 u00b0 c in the form of white crystals a mixture of 3 g 10 7 mmol of 1 2 3 4 tetrahydro 5 8 dimethoxy 2 3 dimethylene 1 4 epoxyanthracene and 30 ml of methyl vinyl ketone was heated at 90 u00b0 c for 24 hours under nitrogen excess methyl vinyl ketone and oligomer formed by the heating were removed by distillation at 110 u00b0 c under reduced pressure 10 2 mmhg the residue was recrystallized from tetrahydrofuran methylene chloride hexane 3 3 5 and yielded 3 5 g 93 of 1 2 3 4 5 12 hexahydro 7 10 dimethoxy 5 12 epoxynaphthacen 2 yl methyl ketone of melting point 167 u00b0 168 u00b0 c in the form of a white amorphous powder 0 2 ml of trifluoroacetic acid was added under nitrogen to a solution of 1 g 2 9 mmol of 1 2 3 4 5 12.