Diethyl zinc catalyzed diastereoselective addition of ketenes to (S)-(+)-3-hydroxytetrahydrofuran

The reaction of (S)-(+)-3-hydroxytetrahydrofuran with phenyl methyl ketene in presence of n-BuLi and Et2Zn results in the formation of the diastereomeric esters (SS+SR) with a high degree of diastereoselectivity (98:2).