Abstract Five monocyclic and one bicyclic 3-(1-chloroalkyl)-1, 2-dioxolanes have been prepared by reaction of alk-3-en-1-yl hydroperoxides with t-butyl hypochlorite in CH 2 Cl 2 in the presence of pyridine or silica; cyclooct-4-en-1-yl hydroperoxide with BuOCl/SiO 2