Nicolaou oxyselenation

Activation of alkenes towards nucleophilic attack by a variety of nucleophiles employing A-phenylselenophthalimide or A-phenylselenosuccinimide as an electrophilic source of the phenylseleno group. 

The reagent may require acid activation depending on the type of transformation being attempted. The mechanism parallels that of halohydrin formation using an electrophilic source of halide in an aqueous medium  

Example 2, in addition to oxyselenide formation, carbo- and heteroseleno cycliza-tion, A -PSP can be used to generate selenides from alcohols and selenol esters from carboxylic acids, respectively, in the presence of a stoichiometric amount of n-Bu,P.  

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Bridged ethers can readily be prepared by the electrophilic attack of various organoselenium reagents on olefins. Nicolaou and his group " have given full details of the attack of selenohalides on unsaturated alcohols (Scheme 21), and oxyselenation of dienes is also effective (Scheme 22). If phenyl selenocyanate is used in the presence of cupric chloride, as the electrophile, the product ratio (123) (124) is strongly solvent-dependent. As the organoselenium substituent... 

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