Pi-diastereofacial selectivity on carbonyl enophile in carbonyl ene reaction: A new insight on the substituent effect in ene cyclization

Pi-facial diastereoselectivity on a carbonyl group in carbonyl ene reaction has been determined using DFT calculation. The effect produced by the electropositive and electronegative group or atom present at the adjacent center reveals that, the face selectivity on the carbonyl group is guided by Cieplak or electrostatic model. The general acyclic model evolved from this observation can be used for determining the preferred orientation of the substituent on the transition structure of type-II ene cyclization.