1,2,6,7-TETRAHYDRO-4H-3,5-BENZODIOXONIN

Temperature-dependent H-1- and C-13-NMR spectra of the title compound are presented. Coalescence effects are discussed and assigned to two d ynamic processes: (a) ring inversion of the nine-membered ring, (b) ra cemization of the enantiomeric ground-state conformations of the nine- membered ring. The barriers are 52 and 35 kJ mol(-1), respectively. Th e stability of the ground state conformation is discussed in terms of transannular hydrogen interactions and anomeric effects. An assignment of the proton signals in the ground-state conformation is proposed.