system MTO/30%H2O2/HBF4/fluorous alcohol is promising for the selective synthesis of biologically important antimalarial dispiro-1,2,4,5-tetraoxanes by direct acid-catalysed cyclisation of various 4-substituted cyclohexanones (1, R=Me, Et, tBu, Ph, COOEt, CF3). The role of the substitutent at the 4-position was important in the selectivity of formation of tetraoxane (2, TO) with respect to hexaoxonane