CONFORMATIONAL STUDIES BY DYNAMIC NMR .56. ENANTIOTOPOMERIZATION AND CONFORMATIONAL ANALYSIS OF HINDERED ARYL ALKYL KETONES INVESTIGATED BY DYNAMIC AND SOLID STATE NMR

摘要

The barriers (Delta G*) for the degenerate interconversion (enantiotopomerization) of a number of mesityl alkyl ketones have been measured by dynamic NMR in a chiral environment. These barriers were compared with those of more hindered ketones having the three methyl groups of the mesityl moiety replaced by three isopropyl groups. These prochiral probes allowed the barriers to be determinated in achiral solvents. The conformations were also assessed by high resolution solid state C-13 NMR and Molecular Mechanics calculations. [References: 23]