One of the most important semisynthetic VLB derivatives prepared
by this reaction was the previously mentioned vinorelbine
(Fig. 2). Similar to that discussed for VLB, while the 13C NMR spectrum
was almost fully assigned, only fragmentary 1H NMR data
were reported by Potier and co-workers in 1979 [74] when this
compound was first synthesized. The first full 1H and 13C assignment
could only been performed in 1992 [75] when the resolution
of a 500 MHz NMR spectrometer and the inverse-detection heteronuclear
correlation measurement techniques became available