Synthesis of 1',3'-Dioxolan-2'-one by the Reaction of Steroidal Oxiranes with Carbon Dioxide: Synthesis of Five-Membered Cis Cyclic Carbonates

The reaction of 3-acetoxy-5,6-epoxy-5-cholestane 1, its 3-chloro analogue 2, and 5,6-epoxy-5-cholestane 3 with carbon dioxide gas in the presence of sodium bromide as catalyst with continuous stirring at 100 degrees C for 30min affords selectively the corresponding 1',3',-dioxolan-2'-ones (steroidal cyclic cis-carbonates) 4-6 in excellent yields. The structures of these products have been established on the basis of their elemental analysis and spectral data (infrared, 1H NMR, and mass).