Cyclisation of citronellal over heterogeneous inorganic fluorides--highly chemo- and diastereoselective catalysts for (+/-)-isopulegol.

Based on a fluorolytic sol-gel synthesis, nanoscopic metal fluorides and partly hydroxylated metal fluorides were synthesized; varying the F : OH ratio inside these solids yielded catalysts with different combinations and variable strength Lewis and Brønsted acid sites, which demonstrated unexpected catalytic properties for the diastereoselective synthesis of (+/-)-isopulegol.