Attempted kinetic resolution of 1,2-diols by camphorquinone: generation of (R)-(chloromethyl)oxirane

Abstract

The epichlorohydrin (R)-(chloromethyl)oxirane has been prepared from rac-3-chloropropane-1,2-diol by means of the chiral ketone D-camphorquinone (1,7,7-trimethylbicyclo[2.2.1] heptane-2,3-dione). These reactions lead to intermediate dioxolanes which can be converted directly into oxiranes. This conversion was effected by reduction of the C-2-ketone of the dioxolane intermediate with sodium borohydride prior to reaction with hydrogen bromide–acetic acid followed by treatment of the resulting acetoxy bromide with sodium ethane-1,2-diolate. The diastereoselective formation of other dioxolanes was also investigated by reaction of D-camphorquinone with ethane-1,2-diol, propane-1,2-diol, and. 3,3-dimethylbutane-1,2-diol.