Selenides, aryl 1-propenyl

Asymmetric oxidation of ( )-3-phenyl-2-propenyl aryl selenides under Sharpless conditions (tetraisopropoxy titanium/tartrate/ferr-butyl hydroperoxide) afforded optically active alcohols in moderate to high enantiomeric excess (25-92% ee) and with yields of about 40%31b. The enantioselectivity in this reaction was enhanced remarkably by an ortho nitro group in the aryl ring and the use of diisopropyl tartrate ligand in the Sharpless oxidation. 

LDA in THF or in THF-HMPT, LiTMP in THF and KDA in THF have all been successfully used for the metallation of phenyl or m-(trifluoromethyl)phenyl vinyl selenide (Scheme 44). The deprotonation was shown to be reversible with LDA in THF and irreversible with LiTMP when performed in the same solvent. Extension of this reaction to homologous derivatives proved difficult since metallation at the allylic sites often competes. Allylic metallation is particularly favorable with aryl 1-propenyl selenides (Scheme 46) - and, whatever the conditions used (LiTMP or KDA ), with aryl 1-(2-methyl-1-propenyl) selenides (Scheme 47). In the latter case both the (Z)- and the ( )-methyl groups have been metidlated leading to the corresponding a-metalloallyl selenides (Scheme 47). - ... 

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