The reaction of phenoxides with symmetrically substituted diaryliodonium salts provides a general route to substituted diaryl ethers. This procedure and other methods were used to synthesise the phthalimido-ester [VI : R = CH2*CH2*N(CO)2C6H4-o] and the corresponding amino-acid (VII) . DIARYLIODONIUM SALTS are readily attacked at position 1 by nucleophiles,2 and thus show promise as general electrophilic phenylating agents. The reaction with phenoxides proceeds, apparently, by a variation of the SN2 m e c h a n i~m ,~.~ and gives diphenyl ethers :We have studied the reaction further because of our interest in diphenyl ethers as intermediates in the synthesis of bisbenzylisoquinoline alkaloids. Since only a few examples have been r e p~r t e d ,~* * *~ the reactions of simple iodonium salts were examined first, in order to establish a suitable procedure and to determine the scope of the method. The ( I ; R = Me, X = Br) Guaiacol Me OMe H H 64 (I; R = Me, X = Br) Vanillin Me OMe H CHO 63 (I; R = Me, X = Br) Isovanillin Me OMe CHO H 65The amino-acid (VII) is required in the synthesis of bisbenzylisoquinolines, and one scheme devised for its preparation involved the reaction of the phthalimido-phenol (V) with the 4,4'-di(methoxycarbonylmethyl)diphenyliodonium salt (IV) and hydrolysis of the product [VI ; R = CH,*CH,*N(CO),C,H,-01. Oxidative iodination of methyl phenylacetate followed by addition of the appropriate inorganic salt gave the diaryliodonium bromide, chloride, or iodide (IV). Heating the iodide at 160" or refluxing its solution in

I l l )short time, but it slowly deposited ammonium tolueiie-9sulphonate. Surprisingly, when the solution was boiled under reflux and the precipitated ammonium toluene-psulphonate filtered off, evaporation of the filtrate gave

The synthesis of a number of substituted 1 : 2 : 3 : 4-tetrahydro-l-0~0quinolizinium bromides is reported. When boiled in acetic anhydride these ketones were converted in high yield into the corresponding substituted quinolizinium salts. From the tricyclic ketones (XXVIII), (XXIX), and (XXX), by similar treatment, the three benzoquinolizinium compounds were obtained.THE simple quinolizinium salts (I; X = I, ClO,, and picrate) were first obtained by Boekelheide and Gall,l by dehydrogenation of the dihydroquinolizinium iodide (11). This method has also been successfully applied to the synthesis of 4-methylquinolizinium saIts (XXIV) but has failed to give 4 : 6-dimethylquinolizinium salts.3 A second synthesis was reported by Richards and Stevens,* who have extended it subsequently to the preparation of a number of alkyl-and aryl-quinolizinium compound^.^ More recently, Nesmeyanov and Rybynskaia have described a synthesis which is specific for the preparation of 2-substituted quinolizinium salts6In a preliminary communication 7 we recorded the conversion of 1 : 2 : 3 : Ptetrahydro-l-oxoquinolizinium bromide 8 (111) into a quinolizinium salt, isolated as quinolizinium picrate (I; X = picrate), by treatment with boiling acetic anhydride containing a drop of sulphuric acid. We now record improvements in this synthesis, together with

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