 If electron-withdrawing substituents such as esters are appended to the C–C bonds, however, the selectivity favors syn addition, so that the bonds donating into σ*C-Nuc are the more electron-rich C–C bonds which are hydrogen-substituted.A similar example is seen in substituted 2-adamantones, where varying the electronic properties at the remote 5 position has profound effects on product distribution.A hydroxyl group is able to donate electron density inductively to the forming σ*C–H bond antiperiplanar, so attack from that side is favored.