In 1957 some dibenzo[d,f][1,3]dioxepines were isolated from Cercospora kikuchii. We describe the preparation of 4,8-dimethoxy-bis[1,3]dioxolo[4,5]benzo[1,2-d; 1',2'-f][1,3]-dioxepine (3). It shows a high SE-reactivity. Bromination yields the monobromo-and dibromocompounds 3 a and 3 b. Treatment of 3 with copper(II) nitrate leads to the dinitrocompound 3c. With the same reagent 3a gives 3d. Reduction of 3d with hydrogen and Palladium as catalyst yields the mono-amine 3e under bromine loss. Under

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... the same reduction conditions in acetic anhydride 3d and 3c yields 3f respectively 3g. The carboxylic acid 3i and the aldehyd 3h are prepared by bromine-lithium exchange from 3 a. In the same manner the dibromocompound 3 b is a suitable starting material to obtain the dicarboxylic acid 3k and the dialdehyd 3j. 3j undergoes easily a thiazolium catalysed oin-condensation, yielding the phenanthrenequinone 3l. The cyclic anhydride 3 m can be prepared by heating 3 k in acetic anhydride.