Phenyl selenyl bromide

Isomerization of epoxides to allylic alcohols can be carried out under mild conditions using diethylaluminium dialkylamides (usually prepared in situ). A useful conversion of olefins into allylic acetates or ethers involves treatment of the olefin with phenyl selenyl bromide or chloride, addition of an alcohol or acid to give a P-substituted selenide (139), and selective oxidative elimination e.g. truns-cyclodode-cene gave 3-acetoxy-trans-cyclododecene in 85% yield. 

Aerial oxidation of cyclopentadecane gives a mixture of cyclopentadecanone and cyclopentadecanol, the yields and product ratio being dependent upon the air flow rate, temperature, and the presence or absence of boric acid. Cyclopentadecanol is the major product in the presence of boric acid, perhaps because the acid catalyses decomposition of an intermediate hydroperoxide. Cyclopentadecanone has been converted into cyclopentadec-2-enone by treatment of its enolate anion with phenyl-selenyl bromide followed by oxidation (+ )-muscone was then prepared by treatment of the cyclopentadec-2-enone with lithium dimethylcuprate (79 % overall). ... 

The addition of selenium reagents to double bonds has already been discussed above. However, a special case of such additions has received particular attention in the past five years this is in the cyclization of olefins. In this context phenyl-selenyl iodide is described as a new rea nt for the cyclization of dienes to carbo-cyclic compounds. The authors claim that phenylselenyl iodide is far more effective than the corresponding bromide or chloride for this transformation. The intramolecular attack of the carbon nucleophile in (287) onto the double bond in the cyclopentene ring is another example of a cyclization reaction and forms the basis for a synthesis of ( )-hirsutene, In this case, the tricycle (288)... 

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