Preparation of functionalised tetrahydropyrans catalysed by isoreticular zeolites

Synthetic organic chemistry targets functionalised tetrahydropyrans (THP) for their large number of biologically active compounds. However, synthetic routes for THPs commonly require multiple, time-consuming steps and/or expensive and environmentally unfriendly catalysts. In this context, we tested zeolites as inexpensive, eco-friendly, thermostable, shape-selective, and industrially relevant catalysts for THP synthesis. Herein, we report the synthesis of 2-phenyltetrahydropyran by (E)-5-phenylpent-4-en-1-ol cyclisation over a set of isoreticular IPC-n zeolites prepared by Assembly-Disassembly-Organisation-Reassembly (ADOR) transformation from a UTL parent material and over commercially available H-BEA catalysts. The results showed that, regardless of zeolite structure, the cyclisation reaction favours the formation of 2-phenyltetrahydropyran as the main product and that reactant conversion and kinetics depend on the total number of acid sites. By contrast, textural properties do not significantly affect conversion or selectivity. Thus, our approach illustrates a facile, inexpensive, and environmentally friendly method for the synthesis of tetrahydropyrans by cyclisation reaction using zeolites as catalysts.