An ¹H NMR study of vinblastine

Abstract

ABSTRACT.The vicinal coupling constants in the 'H nmr spectrum of vinblastine allow a proposal for the conformation of the catharanthine moiety including the nine-membered ring.

Structure elucidation of indole–indoline type alkaloids: A retrospective account from the point of view of current NMR and MS technology

“…As it was already mentioned, the resolution of a 360 MHz NMR spectrometer allowed the full proton NMR assignment of VLB in 1980 [56], almost 20 years after the first fragmentary 1 H NMR assignment of VLB was reported. In this study homonuclear decoupling experiments were used in different media to assign all 1 H resonances and to determine their coupling patterns.…”

“…The first fragmentary 1 H NMR assignment (aromatic OCH 3 , NCH 3 , indole NH, COOCH 3 and OCOCH 3 groups) of VLB was reported in 1962 [12]. Interestingly, almost 20 years had to pass until the first complete 1 H NMR assignment of VLB appeared in the literature in 1980 [56], accomplished on a 360 MHz spectrometer.…”

“…However, the motivation to find more efficient but less toxic VLB analogues initiated the exploration of the structure-bioactivity relationship of bisindoles, leading to attempts to determine their conformational features in solution. The earliest attempt to gain insight into the solution conformation of VLB was performed by de Bruyn et al in 1980 [56]. The authors in this study gave complete 1 H NMR assignments measured at 360 MHz in different non-polar solvents and binary solvent mixtures for VLB, the latter being used to avoid spectral congestion in the 1 H NMR spectrum.…”

“…Making use of the spectral data observed for LEU, on the basis of low-resolution 1 H and 13 C NMR data the structure of C(21 )-oxo-LEU was described improperly [26] as well. The correct ␣-stereoposition of the epoxy-ring in LEU was determined in 1981 [60]. This was based on the relatively small coupling between H-14 and H-15 , and on the reinterpretation of 13 C chemical assignments.…”