PhSeSePh, reactions with

Trialkylboranes were converted into alkyl phenyl selenides and alkyl phenyl tellurides by reactions with PhSeSePh and PhTeTePh in the presence of stoichiometric amounts of air.550 Vinyl selenides and tellurides were synthesized by treating vinylboronic acids or esters with phenylselenyl chloride in ionic liquids (Equation (114))551 or by palladium-catalyzed coupling reaction of diorgano ditellurides (Equation (115)).552... 

The reactivity of 11 was investigated in a stoichiometric reaction with H202 and PhSeSePh in the presence of a hydrocarbon substrate (2 2 1 100 mole ratio). These reagents react in pyridine/AcOH (1.8 1) to give 2 equivalents of the phenylselenyl derivative of the hydrocarbon. 

The vacuum pyrolysis of [Ru3(CO)12] with PhSeSePh at 185°C affords the tetraruthenium cluster [Ru4(CO)n(/i,4-Se)2] (86) (Fig. 28) as the only isolable product.75 By contrast, the reaction of [Os3(CO)10(NCMe)2] with PhSeSePh under mild conditions produces [Os3(SePh)2(CO),0] (87). Apparently, only the Se-Se bond of PhSeSePh is cleaved in this process.7677 In the reaction with the kinetically more labile [Ru3(CO),2] (compared with [Os3(CO)i2]) and with the use of more-forcing pyrolysis conditions, the Se-Se and Se-C bonds rupture and fragmentation of the carbonyl cluster takes place. Isolation of 86 as the major component suggests that this may... 

Athene functionalizations. This reagent can be used for oxidative activation of reagents (e.g., PhSeSePh) to initiate a reaction with alkenes. With participation of proper nucleophiles present in the reaction media addition reactions completed. 

The rate constants for reactions of alkyl radicals with various organic halides demonstrate a clear dependence on the thermodynamics of the reactions. Iodides react faster than bromides, which react faster than chlorides, and the rate constants for reactions for a series of bromides or iodides correlate with the stability of the radical product. The reactions of a primary alkyl radical with an iodomalonate and with a bromomalonate are quite fast (k = 2x 10 M s and k=lx 10 M s, respectively, at 50 °C). To a good approximation, the rate constants for reactions of RSePh are the same as those for reactions of RBr, and the rate constants for reactions of RTePh are about the same as those for reactions of RI. Dichalcogenides are useful for radical functionalization reactions they react with primary alkyl radicals at ambient temperature with the following rate constants MeSSMe, 6 x 10 M s PhSSPh, 2 x lO M s PhSeSePh, 2.6 x 10 M s PhTeTePh, 1.1 x 10 M s... 

Addition of 10 mol% of diphenyl diselenide to hydrostannylation reactions involving electron-rich alkenes resulted in a dramatic improvement in yield. For example, reaction of o - [(f-butyl)dimethylsilyl]oxy styrene with PhsSnH (1.1 equiv.) in the presence of PhSeSePh and 2,2/-azobis(2-methylpropanenitrile) (AIBN) afforded 2- [(f-butyl)dimethylsilyl]oxy -2-phenylethyl triphenylstannane in 95% yield after 2 h. This reaction is believed to benefit from the increased rate of H-atom transfer, resulting from the in sz fM-generated polarity-reversal catalyst benzeneselenol.55... 

Selenenylations of ketones, esters, lactones and lactams are usually effected by the reaction of the corresponding lithium enolates with PhSeCl, PhSeBr and PhSeSePh (with the exception of ketones) at low temperature. Aldehydes have not been selenenylated in this manner. Table 4 illustrates some typical products that have been made in this way. Selenenylation has been especially useful in natural piquet synthesis for the formation of a-methylenelactones from the parent a-methyl compounds (Scheme 15 and Table 4), and has significant advantages over the more traditional methods for ef-... 

The best experimental conditions to introduce a phenylseleno and an azido group to the alkene double bond are those which employ diphenyl diselenide, sodium azide and iodobenzene diacetate in methylene chloride. Under these conditions, however, the addition reaction occurs through the radical mechanism illustrated in Scheme 12 [581. The addition therefore occurs with an anti Markovnikov orientation and it is not stereospecific. The reaction is initiated by the oxidation of the azido anion to the azido radical, which adds to the alkene to afford a carbon radical. This is trapped by the PhSeSePh to afford the final product and a PhSe radical, which dimerizes to give the diselenide. 

Aryl selenides (ArSeAr and ArSeAr ) can be prepared by similar methodology. Symmetrical diaryl selenides were prepared by the reaction of iodobenzene with diphenyl diselenide (PhSeSePh), in the presence of Mg and a copper catalyst. Aryl halides react with tin selenides (ArSeSnR3), with a copper catalyst, to give the diaryl selenide. OS I, 220 III, 86, 239, 667 V, 107, 474 VI, 558, 824. Also see, OS V, 977. 

Synthesis of indium(III) thiolates containing halide donors have also been reported. The oxidative addition reactions of InX (X = C1, Br, I) with PhSSPh yields (PhS)2lnX." Related selenolates can also be synthesized, using PhSeSePh instead of PhSSPh. ... 

Similar reactions can occur where R is a heteroatomic-centred radical such as Me3Sn (from Me Snll), PhS (from PhSSPh), PhSe (from PhSeSePh), PhTe (from PhTeTePh), or PhS02 (from PhS02Cl). In the reactions of PhSSPh, PhSeSePh, and PhTeTePh with allyltrialkyl-silanes, -germanes, -stannanes, and -plumbanes, the reactivity decreases in the sequences S > Se > Te and Pb > Sn > Ge > Si.61 Two examples are given in equations 9-2962 and 9-30.63... 

Table 5-2 summarizes the reaction efficiencies and product profiles for cyclohexane with the Fe(PA)2/HOOH system in the presence and absence of PhSeSePh for various solvents [the py/HOAc (1.8 1 mol-ratio matrix is optimal]. The product profiles for four other hydrocarbon substrates with the relative abundances of the PhSe-K isomers are included in Table 5-2. 

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