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We have studied the possible modification of 2, 5-di(thienyl)pyrroles with the aim of preparing compounds which can serve as precursors of polymers and monomers showing electrical conductivity and specific photochemical properties.2,5-Di(2-thienyl)pyrroles consist of thiophene and pyrrole rings interconnected by their α-positions and are undoubtedly of interest in the preparation from them of electroconductive materials ("organic metals"), in particular as components of organic light-emitting diodes (see, for example, the reviews [1-6]. The extremely high reactivity of a pyrrole system creates the possibility of introducing a substituent into the β-position of the pyrrole ring even with the free α-positions of thiophene rings which makes possible further modification of the properties (especially the solubility of the obtained dithienylpyrrole oligomers and polymers) and also lead to "cross-linking" at the β-positions of thiophene and pyrrole rings. This gives condensed polyheterocyclic compounds with an extended C=C conjugated system which are promising not only for their electroconductive properties but also as structural fragments of photochromic dihetarylethenes. The aim of this work was a study of several electrophilic substitution reactions of 2,5-di(2-thienyl)pyrroles 1a-c together with the subsequent reactions of the products obtained.Vilsmeier formylation of compounds 1a-c gave high yields (82-97%) of the aldehydes 2a-c. Rieche type formylation of aldehyde 2b gave the pyrrole-3,4-dialdehyde 3 (69% based on the aldehyde 2b taking part in the reaction). The product of a Kishner reduction of aldehyde 2a is the corresponding methylpyrrole 4 which undergoes Vilsmeier formylation and also Friedel-Crafts acetylation at the sole unsubstituted pyrrole ring position to form aldehyde 5 (90%) and ketone 6 (59%) respectively.We have also studied the acylation of the N-alkyl-2,5-di(2-thienyl)pyrroles 1a-c using different reagents. The monoacetyl derivative 7a was obtained in low yield (10%) by the action of acetyl chloride on compound 1a in the presence of SnCl 4 in benzene for 4 h but significant tarring occurs. Prolonged holding of the same pyrrole 1a with a mixed anhydride of acetic and trifluoroacetic acids removes the tarring but shows little increase in the yield of the product 7a (14.6%). Acetylation by dimethylacetamide in the presence of POCl 3 was more successful and gave the target ketone 7a in 47% yield. An excess of acetyl chloride with the dithienylpyrrole 1b in the presence of SnCl 4 for 25 min gave the diacetyl derivative 8a in 25% yield. Under the _______ * Dedicated to Boris Aleksandrovich Trofimov on his 70 th jubilee. __________________________________________________________________________________________

A New Approach to the Synthesis of Dithienylethanediones (III) and Dithienyl acetylenes (V). -(BELEN'KII, L. I.; SHIRINYAN, V. Z.; GROMOVA, G. P.; KOLOTAEV, A. V.; STRELENKO, Y. A.; TANDURA, S. N.; SHUMSKII, A. N.; KRAYUSHKIN, M. M.; Chem. Heterocycl.

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Tetrakis(3,5 dimethyl 2 thienyl)ethylene and tetrakis(2,5 dimethyl 3 thienyl)ethylene were obtained from the corresponding dithienyl ketones by the McMurry reaction. The photo chromic properties of the compounds obtained were studied.

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The reactions of henzotrichloride with methyl and ethyl esters and nitriles ~f lthiophene,