DIMESITYLDIOXIRANE

The preparative scale synthesis of dimesityldioxirane (5) via oxidatio n of dimesitylcarbene (6) is described. The dioxirane was obtained as colorless crystalline material, completely stable at -20 degrees C and characterized by spectroscopic methods, X-ray crystallography, and DF T calculations (B3LYP/6-31G(d)). The molecule shows approximately loca l C-2 symmetry with the mesityl rings twisted by ca. 60 degrees. The e xperimental structural parameters, e.g., the O-O distance of 1.503 Ang strom, are in good agreement with the theoretical values. The relief o f steric strain caused by the mesityl groups is discussed in terms of the geometric distortion of the three-membered ring and the mesityl gr oups. Conformational features of 5 in solution are nicely reflected by measured and calculated (SOS-DFPT) NMR chemical shifts.