Conformational analyses of hydrobenzo[c]phenanthridine alkaloids based on 1H relaxation times and nuclear Overhauser effects

Abstract

Conformational analyses based on ¹H relaxation times (T₁) and nuclear Overhauser effects (n.O.e.s) have been carried out for several hydrobenzo[c]phenanthridine alkaloids. Calculated and observed values of T₁ and n.O.e.s have been compared for several possible conformations, and optimum conformations are proposed. These are in reasonable agreement with previous data with the exception of ring B and the N-methyl group. The correlation times for molecular motion have also been evaluated, and are discussed in connection with molecular structures and conformations.