Synthesis and Selected Reactions of Acid Hydrazides Containing an Imidazole Moiety

The preparation of two types of imidazole derivatives bearing a hydrazide group was achieved by treatment of the corresponding esters with NH2NH2·H2O in MeOH at room temperature. In the case of 4-(ethoxycarbonyl)-1H-imidazole 3-oxides 3, hydrazides of type 1 were formed with retention of the N-oxide structure (Scheme 1). Interestingly, due to a strong H-bonding, no deoxygenation of the N-O function could be achieved even by treatment of 3 with Raney-Ni. The second type, 2-[(1Himidazol-2-yl)sulfanyl]acetohydrazides 2, was obtained from 1H-imidazole-2(3H)-thiones 4 in two steps via S-alkylation with methyl bromoacetate, followed by treatment with NH2NH2·H2O (Scheme 2). An imidazole 7, containing both types of hydrazide groups, was prepared analogously from ethyl 2,3-dihydro2-thioxo-1H-imidazole-4-carboxylate 4d (Scheme 4). Both types of hydrazides, 1 and 2, were transformed successfully to the corresponding acylhydrazones 8 and 9, respectively (Scheme 5). Furthermore, it has been shown that hydrazides of type 1 are useful starting materials for the synthesis of 1,2,4-triazole-3thiones 11 and 1,3,4-thiadiazole-2-amines 12, bearing an imidazole 3-oxide moiety (Scheme 7). DOI: 10.1002/hlca.201100292 Posted at the Zurich Open Repository and Archive, University of Zurich ZORA URL: http://doi.org/10.5167/uzh-52668 Accepted Version Originally published at: Mloston, G; Pieczonka, A M; Kowalczyk, E; Linden, A; Heimgartner, H (2011). Synthesis and selected reactions of hydrazides containing an imidazole moiety. Helvetica Chimica Acta, 94(10):1764-1777. DOI: 10.1002/hlca.201100292 Prof. Dr. H. Heimgartner Tel. 044 635 4282 Fax 044 635 6836 e-mail: [email protected] Synthesis and Selected Reactions of Acid Hydrazides Containing an Imidazole Moiety by Grzegorz Mlostoń, Adam Marek Pieczonka), and Ewelina Kowalczyk) University of Łódź, Department of Organic and Applied Chemistry, Tamka 12, PL-91403 Łódź (phone: +48 42 6355761; fax: +48 42 6655162; e-mail: [email protected]) and Anthony Linden and Heinz Heimgartner Organisch-chemisches Institut der Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich (phone: +41 44 6354282; fax: +41 44 6356812; e-mail: [email protected]) ) Part of the planned Ph.D. thesis of A. M. P., University of Łódź. ) Part of the Diploma thesis of E. K., University of Łódź, 2003.