Procedure:  10 mL 1-neck flask, stirbar, septum, N₂ inlet

                  Dissolved 0.038 g of diol I in 2.0 mL of dry CH₂Cl₂.  Stirred at rt and added 0.041 g of carbonyl diimidazole (II).  After 1 h, the solvent was removed from the reaction mixture by rotary evaporation.  The product was isolated by flash chromatography on silica gel using 25:75 EtOAc-hexanes as eluant.  The product was a clear, colorless oil. 

 

¹H NMR (CDCl₃, 400 MHz) d 5.92 (dq, J = 15.2, 6.6 Hz, H2), 5.48 (ddq, J = 15.2, 8.1, 1.7 Hz, H3), 4.56 (dd(apparent t), J = 7.9 Hz, H4), 4.25 (dt, J = 7.8, 4.8 Hz, H5), 1.76 (dd, J = 6.6, 1.6 Hz, H1), 1.73-1.27 (m, CH₂s), 0.87 (t, J = 6.8 Hz, H11). 

 

notes

 

The reaction to form a cyclic carbonate from a 1,2-diol using CDI can be thought of as proceeding as follows...

 

Resonance stabilization within the imidazole ring allows it to perform as a good leaving group.