References
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- Kan-Fan , C. , Husson , H. P. and Potier , P. 1976 . Bull. Soc. Chim. France , : 1227 (-)-craspidospermine
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- The physical constants of 3 were identical with those reported in ref. 4. However, since those authors gave only two 1H signals for the NMR characterization of 3, here we list the full 1H and 13C assignments of this compound, as determined by a combination of high-field [300 MHz (1H)] NMR methods (COSY, HETCOR, DNOE): 1H NMR (CDCl3), δ (ppm): 1.03 (3H, t, H3-21); 1.53 (1H, dq, Hx-20); 1.75 (1H, dq, Hy-20); 2.43 (1H, d, Hβ-15); 2.68 (1H, m, Hβ-6); 2.77 (1H, m, Hβ-6); 2.83 (1H,d, Hβ-15); 3.36 (1H, ddd, Hβ-5); 3.65 (1H, dd, Hα-5); 4.05 (3H, s, OMe); 4.30 (1H, d, H-17); 4.39 (1H, brs, H-3); 6.31 (1H, s, H-19); 6.97 (1H. m, H-12); 7.08–7.15 (2H, m, H-10, H-11); 7.38 (1H, m, H-9). 13C NMR (CDCl3), δ (ppm): 9.1 (C-21); 21.4 (C-6); 24.9 (C-20); 45.6 (C-16); 45.7 (C-15); 49.8 (C-5); 53.3 (OMe); 53.3 (C-3); 63.0 (C-18); 85.2 (C-17); 90.9 (C-14); 111.5 (C-7); 111.8 (C-12); 118.4 (C-9); 121.1 (C-10; 122.7 (C-11); 130.9 (C-8); 134.9a (C-13); 137.5a (C-2; 168.6 (CO). [a = tentative assignmets] A notable feature of 3 is that δ(C-6) is shifted downfield of its ca. 16ppm value typical of the cis D/E ring-fused emburnane skeleton8. This downfield shift is due to the loss of the γ-gauche interaction between C-19 and C-19 and C-6 as a result of the enamine character of N-49
- Bombardelli , E. , Bonati , A. , Gabetta , G. , Martinelli , E. M. , Mustich , G. and Danielli , B. 1975 . Fitoterapia , 2 : 51
- Moldvai , I. , Szántay , Cs. Jr. , Tóth , G. , Vedres , A. , Kálmán , A. and Szántay , Cs. 1988 . Recl. Trav. Chim. Pays-Bas , 107 : 335