Stereoselective acetalization of 1,3-alkanediols controlled by intramolecular van der Waals attractive interactions and its application to an enantiodifferentiating transformation of sigma-symmetric 1,3,5-pentanetriols

Spiroacetal 2 of a folded structure, when compared to the disatereomer 3 of an extended structure, is stereoselectively yielded by the acetalization of several 1,3-alkanediols with methane. The intramolecular attractive interactions between substituents linked on the 1,3-dioxane ring and the menthane moiety, are responsible for the selective development of the folded spirochiral. The stereoselectivity of the reaction can be best established by the functioning of van der Waals attractive interaction.