Backlund Malin, Ziller Joseph, Farmer Patrick J
Department of Chemistry, University of California, Irvine, California 92697-2025, USA.
Inorg Chem. 2008 Apr 7;47(7):2864-70. doi: 10.1021/ic7021962. Epub 2008 Feb 8.
Thione-substituted derivatives of maltol are of interest in several applications of metal-based drugs. In order to investigate the effect of the oxygenation on such thione chelates, Ru complexes of 3-hydroxy-2-methyl-4-thiopyrone (thiomaltol or Htma) and 3-hydroxy-2-methyl-4H-thiopyran-4-thione (dithiomaltol or Httma), Ru(bpy)2(tma), 1, and [Ru(bpy) 2(ttma)] (+), 2, were synthesized as diamagnetic PF6(-) salts. Peroxidation of 2 unexpectedly generated products of C-H activation at its pendant methyl group; an air-stable aldehyde Ru(bpy)2(ttma-aldehyde), 4, was the major product. In addition, an intermediate oxidation product Ru(bpy) 2(ttma-alcohol), 3, was characterized. Both 3 and 4 are also formed by reaction of 2 with outersphere oxidants (e.g., Na2IrCl6) and by bulk electrolysis under anaerobic conditions. Similar oxidations of the analogous Ru(bpy)2(ettma), 2' , complex (3-hydroxy-2-ethyl-4H-thiopyran-4-thione; ethyl dithiomaltol or Hettma) formed the corresponding ketone, Ru(bpy)2(ettma-ketone), 4', by oxidation at the same position adjacent to the conjugated ring. The structures of the aldehyde 4 and starting materials 1 and 2 have been confirmed by X-ray crystallography, and all complexes have been characterized by UV-vis, (1)H NMR, and IR spectroscopies. Initial mechanistic investigations are discussed.
麦芽酚的硫酮取代衍生物在金属基药物的多种应用中备受关注。为了研究氧合作用对这类硫酮螯合物的影响，合成了3-羟基-2-甲基-4-硫代吡喃酮（硫代麦芽酚或Htma）和3-羟基-2-甲基-4H-硫代吡喃-4-硫酮（二硫代麦芽酚或Httma）的钌配合物Ru(bpy)2(tma)（1）和Ru(bpy)2(ttma)（2），作为抗磁性PF6(-)盐。2的过氧化反应意外地使其侧链甲基发生了C-H活化产物；一种空气稳定醛Ru(bpy)2(ttma-醛)（4）是主要产物。此外，还对一种中间氧化产物Ru(bpy)2(ttma-醇)（3）进行了表征。3和4也可通过2与外层氧化剂（如Na2IrCl6）反应以及厌氧条件下的本体电解形成。类似地，对类似的Ru(bpy)2(ettma)（2'）配合物（3-羟基-2-乙基-4H-硫代吡喃-4-硫酮；乙基二硫代麦芽酚或Hettma）进行氧化，在与共轭环相邻的相同位置氧化形成相应的酮Ru(bpy)2(ettma-酮)（4'）。醛4以及起始原料1和2的结构已通过X射线晶体学得到证实，所有配合物均通过紫外可见光谱、(1)H核磁共振光谱和红外光谱进行了表征。文中还讨论了初步的机理研究。
