Hydroxyselenation of allylic alcohols occurs with high regio-and stereoselectivity to give β, β′-dihydroxyphenylselanyl adducts in high yields. An exception is the reaction of the terminal alcohol, 2-methylprop-2-en-1-ol, which forms only a 1, 2-diol product. Generally, the addition is Markovnikov in orientation, but the fact that one anti-Markovnikov addition is observed and that addition to 1, 2-disubstituted alkenes shows a strong preference for one ...