Synthesis of dibenzyl diselenides

A simple, rapid and efficient method has been reported for the synthesis of dibenzyl diselenides under the action of MW irradiation. Benzyl halides are reacted with selenium powder in the presence of a base and phase-transfer agent (Eq. 57 and Tab. 5.29) [80]. The reactions were performed either in THF or in C6H6-H20. 

Tab. 6.32. Synthesis of dibenzyl diselenides under MW + PTC conditions (15 min, 750 W NaOH 15 equiv. PEG-400 5%).

Synthesis of selenopenams starts with commercially available 4-acetoxy-2-azetidinone derivatives which are reacted with sodium benzylselenoate, prepared by treatment of dibenzyl diselenide with sodium borohydride, to give 4-(benzylseleno)-2-azetidinones 97. The radical precursor 98 prepared from 97 was irradiated or heated, and the selenopenams 99 were thus obtained (Scheme 24) <20040BC2612, 2004MOL466, 2001TL4737>. 

Dialkyl diselenides. The synthesis involves treatment of an alkyl halide with Se and Zn dust in aqueous NaOH under nitrogen at 80°C. Access to dibenzyl dise-lenides by a phase-transfer process (Se, NaOH, polyethyleneglycol-400/benzene, 65°C) is also convenient (9 examples, 73-96%). 

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