A tkanson and Polya. * Part I, J . , 1952, 3418. 7 H indicates the position of the " extra " (" indicated ") hydrogen atom.

A number of N-arylazoles were prepared by the Ullmann condensation of various azoles with aryl halides in pyridine. by use of copper( 11) oxide as catalyst. 7001, AustraliaTHE condensation of five-membered heteroaromatic compounds containing a free NH group with aryl halides in the presence of a copper catalyst is related to analogous Ullmann condensations.2-* Some N-aryl heteroaromatic compounds were previously prepared by conducting such condensations in nitr~benzene.~-~ We have prepared various N-arylazoles by use of pyridine as solvent 9 in our condensations. The results are summarked in Tables 2-5;Table 6 contains analytical data for new compounds.Unactivated aryl halides (e.g. bromobenzene, iodobenzene, and 9-bromoanisole) did not arylate 1,2,4-triazole under the Ullmann conditions. Bright coloured solids were noticed in the reaction mixtures, indicating the formation of copper complexes. Similar difficulty was encountered in arylation of azoles by m-chloronitrobenzene in pyridine. Better yields of the arylated products in the o-nitrophenylation of most of the azoles seemed to be due to some special effect, such as ' built-in solvation.' 10Intermediates such as copper phenoxide (and a x-complex with copper phenoxide) and arylcopper have been postulated to take part in the Ullmann diary1 etherll and biaryl l2 syntheses, respectively, and since some of the azoles (benzimidazole, imidazole, and 1,2,4-triazole) are known to form complexes with copper salts13 it is likely that such an intermediate is also responsible for these arylations under Ullmann conditions. However, another mechanism, in which the potassium salt of a heteroaromatic compound reacts as its anion in a coppercatalysed nucleophilic substitution on the aryl halide ,14 can also explain the formation of N-arylazoles; all the azoles employed in the present work give metallic derivatives.

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Acetals of N-unsubstituted 1,2,4-triazole-3-aldehydes have been prepared by condensation of imidic esters with dimethoxyacethydrazide. Free aldehydes couId not be isolated on hydrolysis of the acetals, or on oxidation of propenyl-l,2,4-triazoles. Condensation of imidic esters and acid hydrazides is satisfactory for the preparation of bitriazolyls and methoxymethyl-and cyanomethyl-1,2,4-triazoles.THE preparation of 1,5-diaryl-l,2,Ptriazole-3-aldehydes from the corresponding esters or acid hydrazides (Part VI *) is not a general method. Although the Sawdey rearrangement which has been used to obtain the esters and hydrazides is limited to the synthesis of derivatives of 1,5-diaryl-l,2,4-triazoles, the preparation of l-p-chlorophenyl-5-methyl-l,2,Ptriazole-3-aldehyde (I ; X = CHO) illustrates a convenient synthetic route in some cases. In the reaction illustrated conversion of the ethoxycarbonyl into the aldehyde group by way of an alcohol group follows normal routine.