A stereoselective synthesis of Z??tamoxifen, a tetra??substituted alkene with antiestrogenic activity, is described. The Wittig–Horner reaction has been employed as the key step to establish the olefin stereochemistry. ... A stereoselective synthesis of Z??tamoxifen, a tetra??substituted alkene with antiestrogenic activity, is described. The Wittig–Horner reaction has been employed as the key step to establish the olefin stereochemistry. ... View all references in 1966 by Harper ...