A diselenide

Scheme 15.1 Catalytic cycle for the conversion of a diselenide to a selenenic acid...

The chlorine atom in r/-butyl-2-chloronicotinatc can be displaced with a diselenide group in moderate yield using dilithium diselenide in THF <2003SC3805>. The resulting diselenide is hydrolyzed and cleaved to the chlorose-lenide on treatment with thionyl chloride and catalytic amounts of DMF (Scheme 29). 

Electrochemically generated cation radical 252 derived from the cyclic alkylphenyl selenide 251 can react via two parallel paths deprotonization with the formation of compounds containing double bonds in the selenium-bearing rings and homolytic cleavage of the C(sp3)-selenium bond, followed by dimerization and formation of a diselenide 253 with an extended ring (Scheme 38) <1987ZOB609>. 

A facile synthetic method for a series of macrocycles containing a phosphine oxide group and two selenium atoms was published < 2001J(P 1)1140>. Macrocycles 263 were obtained by a one-pot reaction from 235, which was generated in situ by the previously described procedure from a mixture of potassium selenide and potassium diselenide and dibromides 232. Without isolation, diselenide 235 was treated with potassium borohydride and sodium hydroxide to form a diselenide anion 262, which was allowed to react with various dibromides to give macrocycles 263 with moderate yields. 

It is possible to oxidize an alcohol in the presence of sulfur- or selenium-containing groups (equation 16) using r-butyl hydroperoxide and a diselenide as the oxidizing system (this also oxidizes secondary alcohols, see later).Selenium chemistry can also be used to oxidize benzylic and related primary alcohols to the aldehydes without oxidizing pyridyl (18 equation 17) or thiophenyl (19 equation 18) groups. ... 

The reaction of chiral lithiated ferrocenylamines with dialkylthiuramdisulfides leads to the corresponding (dialkylthiocarbamoyl)thioferrocenes [144]. For catalytic applications, sulfur and selenium derivatives with one [140, 141, 145] or two [146—148] chalcogen substituents have been prepared (see Sect. 4.5.3.1). The technique is essentially the same as for the chiral phosphines lithiation of enantiomerically pure lV,iV-dimethyTl-ferrocenylethylamine, followed either by the addition of a disulfide or a diselenide to the monosubstituted compounds, or by... 

This type of deprotonation procedure can also be applied to prepare lithium or magnesium areneselenolates (143, 148) and sterically hindered silyltelluro-late derivatives of the Group 1 (1A) metals Li, Na, and K (149). An alternative procedure based on the reduction of a diselenide (RSeSeR) with [LiHBEt3] in THF can also afford the desired lithium areneselenolate (32). 

When dimedone was allowed to react with selenium in morpholine, it gave a diselenide 555 that upon heating in ethanol gave... 

The compounds K2EuSiSe5, K2EuGeSe5 are isostructural and they have a layered structure in which 9-coordinate Eu(II) atoms are linked into a layer by (GeSes) units. The (GeSes) " unit, shown in Figure 66(a), is a Ge(IV) tetrahedron with one of its arms being a diselenide unit. It is... 

A diselenide, 2,2 -diseleno-bis-P-cyclodextrin accepts a variety of hydroperoxides as substrates (Liu et al. 2000). The glutathione peroxidase-like activities, reduction of H2O2, ferf-butyl hydroperoxide and cumenyl hydroperoxide by glutathione were 7.4,4.5 and 10.2 U/ unol, respectively. In contrast to ebselen, the diselenide displayed high glutathione peroxidase-like activity. The reduction of hydroperoxide by glutathione in the presence of a radical trap showed that the mimic catalyses the reaction via a non-radical mechanism. 

The phase diagram worked out by Haase et al. [1 to 5] (see p. 309) indicates in its Se-rich region only the existence of a diselenide phase ErSe2 which undergoes a polymorphic a-p... 

---