Photoaddition reactions of 1,3-dioxin-4-ones

Irradiation of 1,3-dioxin-4-ones having l-menthone as a chiral auxiliary in the 2-position in 1,3-dioxolane and oxolane, respectively, affords adducts with good facial selectivities. The benzophenone-initiated photoaddition of isopropanol is also investigated.