text: Similar to intermolecular reactions, intramolecular reactions can show significant stereoselectivity from the ground state conformation of the molecule. In the intramolecular Diels-Alder reaction depicted below, the lowest energy conformation yields the observed product. The structure minimizing repulsive steric interactions provides the observed product by having the lowest barrier to a transition state for the reaction.  Though no external attack by a reagent occurs, this reaction can be thought of similarly to those modeled with peripheral attack; the lowest energy conformation is the most likely to react for a given reaction.
  The lowest energy conformations of macrocycles also influence intramolecular reactions involving transannular bond formation. In the intramolecular Michael addition sequence below, the ground state conformation minimizes transannular interactions by placing the sp centers at the appropriate vertices, while also minimizing diaxial interactions.