Diphenyl 7‘,7>-diselenide

Diselenides can also be oxidatively fluorinated, as shown in equation 18 [118, 119], Benzene selenyl fluoride is postulated as an intermediate during the fluo-roselenation of alkenes with diphenyl diselenide and xenon difluotide [73, 120]... 

Kwon and coworkers have reported the use of diphenyl diselenide 2865"66 and a variety ofben/.ylic selenides (e.g. 29,67 615 30,69 3170 71 and 32K) as photoiniferters for polymerization of S, MM A and some derivatives. Very narrow dispersities were not obtained ( / Mn typically 2-2.5). However, it was possible to prepare... 

Diphenyl diselenide has been prepared by disproportionation of phenyl selenocyanate in the presence of potassium hydroxide" or ammonia/ and by air oxidation of benzeneselenol. The preparation of benzeneselenol is described in an earlier volume in this series/ In the present procedure phenylselenomagnesium bromide formed from phenylmagnesium bromide and selenium is oxidized directly to diphenyl diselenide with bromine/ Thus the liberation of the malodorous and toxic hydrogen selenide and benzeneselenol is avoided. Benzeneselenenyl chloride has been prepared by thermal elimination of ethyl chloride from ethyl phenyl selenide di-chloride/ by thermal elimination of chlorine from phenylselenium trichloride," and by chlorinolysis of diphenyl diselenide with either sulfuryl chloride " or chlorine. " ... 

The benzeneseleninic acid weighs 14.4-16 g. (73-82%) and melts at 123-124°. It may be reconverted to diphenyl diselenide by reduction with sodium thiosulfate or sodium bisulfite. ... 

REAGENTS FOR SYNTHESIS OF ORGANOSELENIUM COMPOUNDS DIPHENYL DISELENIDE AND BENZENESELENENYL CHLORIDE... 

The submitters have carried out this procedure on a 3-mole scale and obtained similar yields. A melting point of 63.5° is reported for diphenyl diselenide. 

Organosei nium Reagents Prepared from Diphenyl Diselenide or Benzeneselenenyl Chloride... 

Another useful reagent for selenenylcyclization is phenylselenenyl triflate. This reagent is capable of cyclizing unsaturated acids101 and alcohols.102 Phenylselenenyl sulfate can be prepared in situ by oxidation of diphenyl diselenide with ammonium peroxy-disulfate.103... 

This reaction depends upon the facile solvolysis of (J-haloselenides and the facile oxidative elimination of a selenoxide, which was discussed in Section 6.6.3. An alternative method, which is experimentally simpler, involves reaction of alkenes with a mixture of diphenyl diselenide and phenylseleninic acid.189 The two selenium reagents generate an electrophilic selenium species, phenylselenenic acid, PhSeOH. 

See Hydrogen peroxide Diphenyl diselenide Hydrazine derivatives... 

Bloodworth, A. J., et al., J. Chem. Soc., Perkin Trans. 1, 1983, 471-473 Attempted thermal dehydration of benzeneseleninic acid, formed by oxidation of diphenyl diselenide with hydrogen peroxide, gave a solid which exploded at 53-55°C. The solid may have been the complex of the acid with hydrogen peroxide. 

The residue in the still (or alkali-insoluble material in the ether layer if Note 6 has been employed) contains diphenyl selenide (b.p. 167°/16 mm.) and diphenyl diselenide (m.p. 63°). It can be separated by a combination of distillation and crystallization from alcohol, but the amounts are small, and, unless the residues from several runs are combined, the procedure is not economical. 

Recently, Kondo and coworkers reported on the polymerization of St with diphenyl diselenides (37) as the photoiniferters (Eq. 39) [ 162]. In the photopolymerization of St in the presence of 37a and 37b, the polymer yield and the molecular weight of the polymers increased with reaction time. The chain-end structure of the resulting polymer 38 was characterized. Polymer 38 underwent the reductive elimination of terminal seleno groups by reaction with tri-n-butyltin hydride in the presence of AIBN (Eq. 40). It also afforded the poly(St) with double bonds at both chain ends when it was treated with hydrogen peroxide (Eq. 41). They also reported the polymerization of St with diphenyl ditelluride to afford well-controlled molecular weight and its distribution [163]. 

Addition of diphenyl disulfide (PhS)2 to terminal alkynes is catalyzed by palladium complexes to give l,2-bis(phe-nylthio)alkenes (Table 3)168-172 The reaction is stereoselective, affording the (Z)-adducts as the major isomer. A rhodium(i) catalyst system works well for less reactive aliphatic disulfides.173 Bis(triisopropylsilyl) disulfide adds to alkynes to give (Z)-l,2-bis(silylsulfanyl)alkenes, which allows further transformations of the silyl group to occur with various electrophiles.174,175 Diphenyl diselenide also undergoes the 1,2-addition to terminal alkynes in the presence of palladium catalysts.176... 

Even the three-component coupling reaction of diphenyl diselenide, ethyl propiolate, and unsaturated compounds occurs under photo-irradiation (Table 5). Alkenes,198,199 1,3-dienes,198,199 vinylcyclopropanes,200 and isocyanides199,201 serve as the unsaturated coupling partner to afford the corresponding coupling products with high regioselectivity. 

Table 5 Photo-induced three-component coupling reaction of diphenyl diselenide, ethyl propiolate, and unsaturated compounds...

Phenyl hydrogen selenide, generated from diphenyl diselenide and sodium borohydride in ethanol, promotes the /V-bcnzylation of cyclohex-2-enylamine (equation 54)164. 

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