Selenium dithiolates

Mammalian thioredoxin reductases are a family of selenium-containing pyridine nucleotide-disulfide oxidoreductases. These enzymes catalyze NADPH-dependent reduction of the redox protein thioredoxin (Trx), which contains a redox-active disulfide and dithiol group and by itself may function as an efficient cytosolic antioxidant [77]. One of the functions of Trx/ thioredoxin reductase system is the NADPH-catalyzed reduction of protein disulfide [78] ... 

This enzyme also contains an N-terminal pyruvoyl residue as does one subunit of a selenium-containing glycine reductase which utilizes a dithiol to convert glycine into acetate with coupled formation of ATP ... 

There are single examples of sulfur and selenium xanthates with the remaining structures to be described in this section featuring tellurium as the central element. There are a significant number of binary xanthates and, in common with these, their organotellurium xanthates feature extensive supra-molecular association, usually, but not exclusively, via Te- S secondary bond interactions. A rare example of mixed-ligand 1,1-dithiolate structure is available where the odd dithiolate ligand is a dithiocarbamate. 

Other structures such as a-(l,2-dithiol-3-ylidene)ketones (12) can be named according to common nomenclature because they do not possess the symmetry of the l,6,6a Slv-trithiapentalenes. However, even with such unsymmetrical systems, pentalene names may be useful, either to stress the fact that three heteroatoms are in line or to show the similarity with trithiapentalene derivatives, for instance, in the case of selenium analogs (13). 

J. B. Guttenplan, T. E. Spratt, M. Khmelnitsky, W. Kosinska, D. Desai, K. El-Bayoumy, Effects of 3H-l,2-dithiole-3-thione, l,4-phenylenebis(methylene)sele-nocyanate, and selenium-enriched yeast individually and in combination on benzo[a]-pyrene-induced mutagenesis in oral tissue and esophagus in lacZ mice, Mutat. Res., 559 (2004), 199 D210. 

The reduction of the di(selenocyanato)propane 169 with sodium borohydride gave the corresponding diselenolate, which reacted with 3-chloropropan-l-thiol to give the dithiol 238 in 60% yield. A soft base like cesium carbonate in DMF was able to deprotonate the dithiol and treatment with 1,3-dibromopropane afforded the sulfur and selenium 16-membered ring heterocycles 239 in 22% yield <2000IC2558>. Bis(o-formylphenyl)telluride 241 was synthesized... 

The dibromoselenurane 140 was also applied as a selenium transfer reagent in the formation of trichalcogen bonds in metallocenophanes. Thus,2-selena-l,3-dichalcogen[3]metallocenophanes 163 were obtained in high to moderate yields from the appropriate metallocene-1,1 -dithiols or -diselenols 164 upon treatment of 140 [75] (Scheme 19). 

Oxidation with iodine in EtOH of the selenium-containing zincate salt 423 afforded the oligomeric derivative 424, which was depolymerized with PBus to give the reactive 1,2-diselenone 425. The latter was trapped with dimethyl acetylenedicarboxylate (DMAD) to afford the 1,4-diselenine 426, which was subsequently converted into the 1,4-diselenine-2,3-dithiolate 427 with sodium methoxide (Scheme 59) <1997CC2293, 2000CEJ1153>. 

Thiophen-fused 1,3-dithiol-2-thiones and related selenium-... 

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