The determination of the molecular framework and conformation of the calpaurine alkaloid by 1d- and 2d- NMR methods

Abstract The structure and conformation of calpaurine, a novel quinolizidine alkaloid, has been studied and found to be that of the 3(β),4(α)-dihydroxy,13(α)-O-(2'-pyrrolylcarbonyl) derivative of lupanine. The approach used for building the molecular framework is based on the use of mono- and bi-dimensional NMR technique and the knowledge of the molecular formula of calpaurine.