Hydroxy-santhones and -benzophenones are conveniently obtained from hydroxybenzoic acids and phenols in presence of zinc chloride and phosphorus oxychloride.DISTILLATION of a mixture of a phenol, a phenolic acid, and acetic anhydride is the earliest and simplest method for the synthesis of hydroxyxanthones (Michael, Amer. Chsm.
In continuation of previous work (Part I ; this vol., p. 228), di-and tri-hydroxyphenyl ketones have been condensed with ethyl acetoacetate in the presence of aluminium chloride to give hydroxyacylcoumarins. Orcacetophenone and 2 : 4dihydroxybenzophenone afford 5-hydroxy-6-acylcoumarins, similarly to resacetophenone. The probable mechanism of the formation of 5-hydroxycoumarin derivatives in such cases is discussed ; it is suggested that the chelation between the acyl and the o-hydroxyl groups fixes the double bonds in the nucleus, the condensation then taking place a t the 3-position with subsequent ring closure to a 5-hydroxycoumarin.IN Part I, with Sethna (this vol., p. 228), we showed that methyl p-resorcylate, (3-resorcylic acid, and resacetophenone smoothly condense with ethyl acetoacetate in the presence of aluminium chloride , giving otherwise difficultly accessible 5-hydroxycoumarin derivatives, and the study has now been extended to the condensation of ethyl acetoacetate with a number of phenolic ketones, viz., orcacetophenone, 2 : 4-dihydroxybenzophenone, 2acetylresorcinol, and phloracetophenone.Condensation of 0rcacetophenone.-Orcacetophenone on condensation with ethyl acetoacetate in presence of aluminium chloride similarly to resacetophenone (Part I, loc. cit.) gave a mixture of 5-hydroxy-6-acetyl-4 : 7-dimetlzylcouanarin ( I ) and 5-hydroxy-4 : 7dimethylcoumarin (11) ; the latter was identical with the product obtained by the condensation of orcinol with ethyl acetoacetate in presence of sulphuric acid (Pechmann and Cohen, CH HO/\OH CH*AcCO,Et V O M e Me Me (I.) CH / CH OC/>CMe facet yla tion I Ber., 1884, 17, 2188), and its formation is probably due to the elimination of the acetyl group from (I) during the reaction. When sulphuric acid was used as condensing agent,
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