(+)-N-Formylnorglaucine Rotamers from Unonopsisstipitata DIELS

(+)-N-formylnorglaucine (1), an aporphine alkaloid containing a formyl group linked to the heterocyclic nitrogen, was isolated from the leaves of Unonopsisstipitata, an Amazon medicinal plant. The chemical structure was characterized based on 1D- and 2D-NMR spectroscopy and HR-ESI-MS. NMR spectra revealed that 1 is composed of two rotamers (1a and 1b) in a ratio of approximately 2:1. In addition, the fragmentation behavior of 1 displayed an unusual fragmentation pattern compared to regular aporphine alkaloids. Thus, this compound is reported for the first time as a natural product in this study.