Utilization of protopine and related alkaloids. XVII. Spectroscopic studies on the ten-membered ring conformations of protopine and .ALPHA.-allocryptopine.

Abstract

The infrared carbonyl absorptions of protopine and α-allocryptopine in dilute carbon tetrachloride solution and nuclear Overhauser effect experiments in the proton nuclear magnetic resonance spectra have shown that these alkaloids each interconvert between two major conformations of the ten-membered ring. These conformations are discussed on the basis of the observed spectral data.