Syntlikses dans le domaine des hydrocarbures cancCrig&nes X (*) Le 9,10-dim&hyl-l,2,3,4,5,6-tribenzanthrac&ne P. LAMBERT et R. H. MARTIN (Bruxelles) SUMMARY. -9,10-dimethyl-1,2,3,4,5,G-tribenzanthracene (VII) has been prepared from the corresponding quinone by the method of Sandiri and Fieser. A new synthesis of 1,2,3,4,5,6-tribenzanthraquinoiie (VI) involving the following steps is described : condensation of phenanthrene-9,10dicarboxylic anhydride (IV) (preparation improved) with l-naphthylmagnesium bromide [9-(or-naphthoyl)-lO-phenanthroic acid (V)], ryclisation with I-I,PO, + P205 [1,2,3,4,5.,G-tribenzanthraquinone ; small yield]. The acetoxy-lactone (VIII) was isolated after treatment of the crude reaction mixture with acetic anhydride. Other cyrlising agents such as C,H,COCI + H2S0,, phthalic anhydride + C,H,COCl, H,BO, + II,SO, and ClS0,H failed t o give the desired quinone.
Attempts to cyclise 0-( P-naphthoy1)-10-phentnthroic acid (IX), an isomere of the above keto-acid, gave no better results.
The oxydation of 1,2,3,4,5,G-tribenzanthracene with sodium bichromate in acetic acid has been shown to give a mixture of three quinones : 1,2,3,4,5,G-tribenzanthraquinone (m.p. 250-2510 ; yield : 52%), a n orthoquinone (only detected by isolation of the corresponding phenazine) and an ortho-para-bisquinone (imp. 318-3200).