Selenides, alkenyl phenyl

In the presence of base, phenylselenenyl bromide reacts with alkenyldihydroxyboranes to give alkenyl phenyl selenides with retention of configuration at die double bond (equation 73). 

Increasing the substitution of the alkyl group on the 3-carbon of 1-alkenyl phenyl selenides again favors metaliation at the vinylic site (Scheme 48). > KDA in THF has proved to be, without contest, the most successful reagent for this purpose. The reaction takes place at low temperature (-78 C) and the 1-phenylselenoalkenyl metal, produced in almost quantitative yield, retains its stereochemistry (Scheme 48, b-d). 

Alternatively, 1-lithio-l-alkenyl phenyl and methyl selenides have been obtained on reduction of the C—Se bond of l,l-di(seleno)alkenes with alkyllithiums this reaction is the only one which allows the synthesis of the methylseleno derivatives (Scheme 41). ... 

The coupling of arylzinc halides with alkyl (E)-2,3-dibromoalkenoates occurs at C-3. 3-Arylindoles are obtained from 3-indolylzinc halides with haloarenes." A synthesis of 1,4-disubstituted butadienes starts from the hydrozirconation of ethynyl phenyl selenide. After Pd(0)-catalyzed coupling with alkenyl bromides, the seleno group is replaced via Grignard reaction in the presence of (Ph3P)2NiCl2. 

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