Sodium benzyl selenide

A related radical transformation can be used to prepare 2,2-disubstituted selenanes. Treatment of the alcohol 124 with oxalyl chloride followed by addition of 2-mercaptopyridine iV-oxide and heating afforded the selenane 125 in moderate yield (Scheme 11) <2001JOC6286>. The required alcohol precursor for this reaction can be readily prepared from the bromo ester and in ////-generated sodium benzyl selenide, followed by Grignard addition. 

A -methyl-5//,7//-dibenzo[d,.g][l,5]telluroazocine 65, its thiooxide 67a (X=S, R= Me) (95JA6388). The same type of reaction with benzylamine and sodium selenide gives A-benzyl-5//,7//-dibenzo[d,g][l,5]telluroazocine selenoxide 67b (X = Se, R = CH2Ph). Reaction of the tellurium dibromide 66 with sodium sulfide carried out in the absence of the primary amines affords the eight-member Te,S-containing heterocycle 5//,7//-dibenzo[d,g][l,5]telluroazocine (92CL151). 

In the case of the benzyl compound, sodium selenide is treated with benzyl chloride ... 

By treating sodium selenide with benzyl chloride. 

This selenide may be obtained as follows (1) Phosphorus pentaselenidc (P2Se5) is treated with alcoholic sodium hydroxide until sodium selenide is produced, air being excluded during the operation. Benzyl chloride is then added and the mixture heated under reflux. Evaporation away of the solvent yields white needles of the selenide, together with yellow scales of the diselenide.8 (2) Potassium selenosulphate is... 

Dibenzyl diselenide, (C6H5.CH2)2Se2.—This compound may be obtained in a variety of ways (1) Sodium selenide is heated for several hours under reflux with benzyl chloride in alcoholic solution.2 (2) A good yield of the diselenide results when a solution of selenium in sodium sulphide or sodium hydroxide is shaken on a machine with benzyl chloride.3 (3) Potassium selenosulphate is shaken with the calculated quantity of benzyl chloride in the cold. (4) An alcohol solution of potassium benzyl selenosulphate is treated with an excess of iodine, and the diselenide remaining in solution is precipitated by the addition of water. The precipitate is collected immediately and recrystallised from alcohol, since the presence of iodine appears to aid decomposition, with deposition of selenium, and it is also necessary to wash the crystals with water to remove any traces of hydriodic acid before drying the product.4 (4) An aqueous solution of potassium benzyl selenosulphate is subjected to electrolysis, using a current of 0 25 to 0 5 ampere, the method of operation being similar to that used for di-p-nitrobenzyl diselenide. 

Dimethyl selenide, 28 grams, is added to 43 grams of benzyl bromide, the resulting brown mass dissolved in water, and the picrate precipitated by the aid of sodium picrate. The yield is about 38 grams, the product separating from alcohol in small needles, M.pt. 118° C. 

Sodium periodate is also frequently used as an oxidant for selenides, the reaction proceeds slowly in aqueous methanol. Various selenoxides such as methyl phenyl and benzyl phenyl selenoxides, (3B), (39),2 (40) and 2-azidocyclohexyl phenyl selenoxide have been isolated in this way. Other solvents and reaction conditions may also be employed. " °... 

Reactions with Nucleophiles. The epoxide is, by far, the more reactive site and a wide variety of nucleophiles have been used (eq 2) to open the ring at C-3 such as HCl (96%), HOAc (>50%), H2S (65% as cyclized product 3-thietanol), HCN (66%), ethanol (90%), t-butanol (86%), phenyl or benzyl thiol (99% or 93%, respectively), and phenyl selenide (generated in situ from the diselenide and sodium hydroxymethyl sulfite) (>55%). If desired, the epoxide is easily formed from the chlorohydrin by treatment with excess KOH or Et3N. 

Diphenyl selenide is oxidized with peroxyacetic acid at room temperature to diphenyl selenoxide hydrate, C6H5Se(OH)2, in 43% yield after 2 h [1198]. Benzyl phenyl selenide is oxidized to benzyl phenyl selenoxide by sodium periodate in aqueous methanol at 0 °C in 95% yield and by iodobenzene dichloride in aqueous pyridine at -40 °C in 85% yield [773]. 

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

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