DIMESITYLKETONE O-OXIDE - VERIFICATION OF AN UNUSUALLY STABLE CARBONYL OXIDE BY NMR CHEMICAL-SHIFT CALCULATIONS

NMR chemical shift calculations in combination with geometry optimizat ions both based on density functional theory were used to identify and to describe dimesitylketone O-oxide (6), which is the first carbonyl oxide that could be generated in solution at - 78 degrees C and invest igated by NMR spectroscopy. The conformation of carbonyl oxide 6 is ch aracterized by two orthogonal mesityl rings and a close O,H contact be tween one of the H atoms of the mesityl methyl groups and the terminal O atom of the carbonyl oxide, The calculated geometry and conformatio n of 6 are verified by the agreement of calculated and measured NMR ch emical shifts, The unusual rearrangement of 6 to an alcohol is explain ed.