Selenol - Selenium sulfide

Carbonsulfur bonds can be formed by the reaction of elemental sulfur with a lithio derivative, as illustrated by the preparation of thiophene-2-thiol 446. If dialkyl or diaryl disulfides are used as reagents to introduce sulfur, then alkyl or aryl sulfides are formed sulfinic acids are available by reaction of lithium derivatives with sulfur dioxide. In the pyrrole series, a 2-thiol and the corresponding selenol can be prepared via reaction of 2-lithio-l-methylpyrrole with sulfur or selenium, then trapping with Me3SiCl leading to the 2-Me3SiX-substituted derivatives <1997T13079>. 

For the preparation of the diselenide, the monoselenide [e.g., made from (9H-9-BBN)2 and selenium powder (see above)] is heated at 120° with an equivalent amount of black selenium powder until the elemental selenium is dissolved. The one-step synthesis of the diselenide from (9H-9-BBN)2 and selenium is also possible. However, the product is not as pure as in the two-step process, as it is normally contaminated with some selenol and the products thereof (see the preparation of the CgHi4B sulfides). - ... 

Metal thiolate complexes will reduce elemental sulfur or red selenium via the oxidative elimination of RSSR. In a similar manner, metal selenolate complexes ean be used to reduce elemental selenium. The resulting E ligands favor the formation of polynuclear cluster complexes, due to the greater tendency of E (vs. RE ) to form bridging interactions between metal centers. Originally developed in the synthesis of [Fe4Se4(SPh)4], this method has been well utilized in the synthesis of a number of iron thiolate/sulfide clusters, as well as their selenide counterparts (Equation (5)). More recently, sulfur- and selenium-containing lanthanide clusters (see Section 7.2.5.5) have been synthesized by the displacement of ER from Ln(ER)3 ... 

Treatment of selenol 49 with 5-nitrosoglutathione (GSNO) resulted in the NO transfer from sulfur to selenium to produce 5e-nitrososelenol 50, which reacted with 1-buta-nethiol to afford selenenyl sulfide 52 (Scheme 11.28). While Se-nitrososelenol 50 was reduced to selenol 49 by DTT in the presence of base, selenenyl sulfide 52 showed no reaction under the same conditions. These results are supportive for the proposed mechanism for the GPx inactivation shown in Scheme 11.27, suggesting that Se-nitrosation of selenoproteins may play an important role in redox regulation systans. 

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