Metal-Free Synthesis of 1,3-Dioxane Derivatives from Aromatic Alkynes and Paraformaldehyde

Here we report the efficient synthesis of a series of 1,3-dioxane derivatives from aromatic alkynes, paraformaldehyde, and a Lewis acid catalyzed reaction at room temperature. This reaction is metal-free and atom-economic. Single crystals of two typical 1,3-dioxane derivatives are obtained. A mechanism that the reaction proceeds through a six- or eight-membered ring intermediate is proposed.