Condensation of catechol [120-80-9] (1) with epichlorohydrin in the presence of an aqueous base can be visualized as proceeding initially with the epoxide (2) Opening of the oxirane ring by the phenoxide anion then leads to 2-hydroxymethyl-1,4-benzodioxane [3663-82-9] (3). Halogenation with thionyl chloride gives 2-chloromethyl-1,4-benzodioxane [2164-33-2] (4). Displacement of the leaving group by piperidine completed the synthesis of piperoxan (5).
^Fourneau E, Bovet D (1933). "Recherches sur l'action sympathicolytique d'un nouveau dérivé du dioxane". Archives Internationales de Pharmacodynamie et de Thérapie. 46: 178–91. ISSN0003-9780.