Synthesis of 5-heptadecyl- and 5-heptadec-8-enyl substituted 4-amino-1,2,4-triazole-3-thiol and 1,3,4-oxadiazole-2-thione from (Z)-octadec-9-enoic acid: preparation of Palladium(II) complexes and evaluation of their antimicrobial activity

Two 4-amino-1,2,4-triazoles and two 1,3,4-oxadiazoles are obtained in a common synthetic route including hydrogenation-hydrazidation of (Z)-methyl octadec-9-enoate to octadecanoic hydrazide under atmospheric air. Preservation of olefinic bond in heptadec-8-enyl group is achieved by carrying out hydrazidation reaction under the presence of an argon atmosphere. The disappearance of the olefinic bond is detected by physical data, IR, 1H, and13C NMR spectroscopy. New palladium complexes derived from 4-amino-5-heptadecyl-1,2,4-triazole-3-thiol and 5-heptadecyl-1,3,4-oxadiazole-2(3H)-thione are obtained and characterized by elemental analysis (solid state), IR, 1H, 13C NMR spectroscopy, XRD, and XPS. These resulting metallic entities are also identified in solution based in mass spectrometry (MS-ESI) experiments. Most compounds and their palladium(II) complexes are tested in vitro against Gram-positive, Gram-negative bacteria, and fungi, some of them showed variable activity.Financial support was provided by the Spanish Ministerio de Ciencia e Innovación (MICINN) (projects CTQ2010-20387, and Consolider-Ingenio 2010, CSD2007-00006), the Spanish Ministerio de Economía y Competitividad (MINECO) (projects CTQ2013-43446-P, and CTQ2014-51912-REDC), FEDER, the Generalitat Valenciana (PROMETEO 2009/039 and PROMETEOII/2014/017) and the University of Alicante. One of us (M.C.) thanks USTO-MB for scientific leave