SOLID-STATE NMR-STUDY OF THE KINETICS OF A RING-CHAIN TAUTOMERISM IN A TETRAHYDRO-1,3-OXAZINE DERIVATIVE

Condensation of cis-2-aminomethylcyclohexanol with p-nitrobenzaldehyde under mild conditions initially gives the imine as the kinetically co ntrolled product. The imine undergoes a solid-state rearrangement to t he bicyclic tetrahydro-1,3-oxazine. The kinetics of the rearrangement were followed by solid-state CP/MAS C-13 NMR spectroscopy over the tem perature range 283-297 K and the reaction was shown to have an activat ion energy of 85.0 +/- 14.7 kJ mol(-1). The probable reaction mechanis m is discussed.