Results With a view to examining the behavior of pinacols with acetic anhydride and 4- (dimethy1amino) pyridine at high concentrations, the representative substrate, 2, 3-di- hydroxy-2, 3-dmethylbutane (la), was treated with DMAP (1 equiv) and acetic anhydride (2.2 equiv) at ca. 85" C for 3 h. A colorless crystalline compound was isolated, mp 179-180" C (51%), which was identified as the cyclic carbonate 2a, 2-oxo-4, 4, 5, 5-tetramethyl-1, 3- ...