Carbon-13 Variable Temperature NMR Studies of Some Dimethyl-1-oxa-3,4-diazacyclohexanes1

Conformational equilibria are elucidated and rationalised for 3,4-dimethyl-1-oxa-3,4-diazacyclohexane, and a trans-bicyclic analogue. The major conformer has 3ax-NMe, 4eq-NMe: two minor conformations are also significantly populated. Kinetic and thermodynamic parameters are correlated with those for analogous heterocycles.