Ethyl phenylselenide

Tris[(2-perfluorohexyl)ethyl]tin hydride has three perfluorinated segments with ethylene spacers and it partitions primarily (> 98%) into the fluorous phase in a liquid-liquid extraction. This feature not only facilitates the purification of the product from the tin residue but also recovers toxic tin residue for further reuse. Stoichiometric reductive radical reactions with the fluorous tin hydride 3 have been previously reported and a catalytic procedure is also well established. The reduction of adamantyl bromide in BTF (benzotrifluoride) " using 1.2 equiv of the fluorous tin hydride and a catalytic amount of azobisisobutyronitrile (AIBN) was complete in 3 hr (Scheme 1). After the simple liquid-liquid extraction, adamantane was obtained in 90% yield in the organic layer and the fluorous tin bromide was separated from the fluorous phase. The recovered fluorous tin bromide was reduced and reused to give the same results. Phenylselenides, tertiary nitro compounds, and xanthates were also successfully reduced by the fluorous fin hydride. Standard radical additions and cyclizations can also be conducted as shown by the examples in Scheme 1. Hydrostannation reactions are also possible, and these are useful in the techniques of fluorous phase switching. Carbonylations are also possible. Rate constants for the reaction of the fluorous tin hydride with primary radicals and acyl radicals have been measured it is marginally more reactive than tributlytin hydrides. ... 

The total synthesis of Stemona alkaloid (-)-tuberostemonine was accomplished by P. Wipf. Late in the synthesis, the introduction of an ethyl sidechain was required. This could be achieved in a novel four-step sequence. First, the allyl sidechain was introduced by the Keck radical allylation. To this end, the secondary alkyl phenylselenide substrate was treated with allyltriphenyltin in the presence of catalytic amounts of AIBN. This was followed by the introduction of a methyl group onto the lactone moiety. The allyl group then was transformed into the desired ethyl group as follows the terminal double bond was isomerized to the internal double bond by the method of R. Roy. This was followed by ethylene cross metathesis and catalytic hydrogenation to provide the desired ethyl sidechain. 

S-ethyl as LGC.114 First, the bromide donor 77 was activated over the phenylselenide acceptor 78 in the presence of AgOTf/y-collidine to give the desired disaccharide 79 in 60% yield. The latter was then directly activated over the SEt acceptor 80 by the addition of Ag0Tf/K2C03 to produce the desired trisaccharide 81 in 81% yield. Apparently, the trisaccharide 81 can be directly activated for subsequent glycosyl-ations. A similar activation sequence was reported by Ley s group.116... 

An ethanolic soln. of benzyl bromide and Na-phenylselenide refluxed 2 hrs. -> benzyl phenyl selenide (Y almost 100%) treated with Li-diisopropylamide and ethyl bromide in tetrahydrofuran, the resulting crude mixture treated with 30%-H2O2, and the product isolated after 24 hrs. -> product. Overall Y 80%. F. e. s. R. H. Mitchell, Chem. Commun. 1974, 990 syntheses of ethylene derivs. via a-metalation of selenoxides cf. H. J. Reich and S. K. Shah, Am. Soc. 97, 3250 (1975). 

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