13P-Methoxylupanine

New reports on hydroxy and methoxy derivatives include the isolation of (-)-6a-hydroxylupanine from Lygos raetam var. sarcocarpa [219] and the isolation of two methoxylated derivatives, 4a-hydroxy-13p-methoxy-lupanine and 3P,4a-dihydroxy-13p-methoxylupanine, from Acosmium panamense, as well as the full spectroscopic characterisation of the previously known ISP-methoxylupanine, Fig. (34) [220]. 

Comparison of the NMR data of 4a-hydroxy-13 P-methoxy lupanine and 3P,4a-dihydroxy-13P-methoxylupanine with that of 13P-hydroxylupanine led the authors to propose the depicted structures the hydroxyl group of 4a-hydroxy-13 P-methoxy lupanine was evident in the mass fragment at m/z 294 (C16H26N2O3) and resonances at 5 3.92 ppm and 5 63.2 ppm, the latter replacing the C-4 resonance (6 19.4 ppm) in the C NMR spectrum of 13 P-methoxy lupanine, and its a orientation was determined on the basis of the H-4 multiplicity and magnitude of the observed upfield shift of the C-4 and downfield shift of the C-3 and the C-5 resonances, when compared to a known 4P-hydroxylupanine derivative (4P-hydroxy-13a-0-(2 -pyrroyl-carbonyl)-lupanine). 

Fig. (34). Structures of the tetracyclic lupine alkaloids (-)-6

---