Abstract The selenoacetals 4 having a chiral center in the β-position were subjected to selenium/lithium exchange by butyllithium in ether. The resulting α-phenylseleno alkyllithium compounds 5 undergo rapid epimerization at− 78 C. Trapping of these organolithium compounds by ketones or aldehydes appears to be faster than the epimerization. The ratio of the trapping products therefore reflects the equilibrium ratio of the diastereomeric α- ...
