Total assignment of the proton and carbon NMR spectra of 5′-NOR-anhydrovinblastine

Total spectral assignment of the bis-indole alkaloid Navelbine®, 5′-nor-anhydrovinbIastine, was accomplished using a combination of two-dimensional nmr techniques. Conventional homonuclear and inverse-detected experiments were supplemented with the HMQC-TOCSY experiment to unequivocally assign carbons directly bound to overlapped protons. In addition, the recently introduced GEM-COSY experiment was evaluated as a technique for the identification of geminal methylene pairs. Partial assignments proposed by Potier and co-workers, based on chemical shift considerations, are largely in agreement with the unequivocal assignments determined in this study.