Conformational transformations of lupinine in the formation of protonated forms and quaternary salts

Abstract

1. The results of a study of IR and PMR spectra have shown that in solution protonated lupinine exists in two interconverting cis-trans conformations the relative amounts of which depend on the temperature, the concentrations of base and water, and the pH of the medium. This process is possible because of a change in the direction of the unshared pair of the nitrogen atom in the inversion process. 1. On the basis of the PMR and IR spectra, lupinine methiodide has the a,e conformation with an e-CH2OH group and epilupinine methiodide has the a,a conformation with an e-CH2OH group.