Use of 1,3‐dioxin‐4‐ones and their related compounds in synthesis. Part 28. Asymmetric de mayo reactions using chiral spirocyclic dioxinones

Abstract

The use of rigid spirocyclic dioxinones having 1‐menthone as the chiral auxiliary as the enones in the photo[2 + 2]cycloaddition reactions opened novel methods for obtaining enantiomerically pure compounds, such as iridoids. Convex side preference of the sofa‐conformation of these dioxinones in the photoaddition to cyclopentene increases up to 100% by introducing either a bulky substituent or 5‐hexenyl group at the 3‐position to these dioxinones and, hence, highly asymmetric inter‐ and intramolecular de Mayo reactions have been disclosed.