Hydroxyselenation of terminal or cyclic allylic alcohols occurs with h
igh regio- and stereoselectivity to give beta,beta'-dihydroxyphenylsel
enated adducts in high yields. A mechanism for this selectivity is pro
posed. The utility of these adducts is illustrated by the conversion o
f the hydroxyselenide (9a) to the epoxide (11) via the intermediacy of
a selenone.