π‐Facial Selectivity of the Singlet Oxygen (4 + 2) Cycloaddition to Chiral Naphthalene Derivatives: The Directing Effect of Carbon‐ Containing Substituents.

Abstract A set of five chiral naphthalene derivatives 1 gave on photooxygenation the corresponding endoperoxides in excellent yields; the diastereoselectivity of singlet oxygen attack was determined and the directing effect of various carbon-containing substituents (CN, COOH, COOMe, CHO, CH 2 OH) was rationalized in terms of attraction or repulsion in the transition state through electronic and steric effects.