 Experimental evidence, however, shows that axial electron-withdrawing C4 substituents are more directing towards axial attack than equatorial substituents.Since axial orbitals are not aligned for hyperconjugation in this system, Houk rationalized this trend by invoking electrostatic arguments, described below.In an effort to explain the surprising stereoselectivies in the systems above, alternative explanations to the Cieplak effect have been proposed.