Synthesis of Vinca Alkaloids and Related Compounds. PART LVIII. A Novel Formal Synthesis of (−)-Criocerine from (+)-Vincamine

References

• Sóti , F. , Incze , M. , Kardos-Balogh , Zs. , Kajtár , M. and Szántay , Cs. J. Chem. Res. (S) , For part LVII see, in press
   Google Scholar
• Neuss , N. , Boaz , H. E. , Occolowitz , J. L. , Wenkert , E. , Schell , F. M. , Potier , P. , Kan-Fan , C. and Plat , M. 1973 . Helv. Chim. Acta , 56 : 2660 (-)-Vincarodine
   PubMedGoogle Scholar
• Kan-Fan , C. , Husson , H. P. and Potier , P. 1976 . Bull. Soc. Chim. France , : 1227 (-)-craspidospermine
   Google Scholar
• Mitra , A. K. , Patra , A. and Mukhopadhyay , A. K. 1981 . Phytochemistry , 20 : 865 (-)-vincapusine
   Google Scholar
• Bruneton , J. , Kan-Fan , C. and Cave , A. 1975 . Phytochemistry , 14 : 569
   Google Scholar
• Hugel , G. , Gourdier , B. , Levy , J. J. and Le Men , J. 1980 . Tetrahedron , 36 : 511
   Google Scholar
• Beugelmans , R. , Herlem , D. , Husson , H. P. , Khuong-Huu , F. and Le Goff , M. T. 1976 . Tetrahedron Letters , : 435
   Google Scholar
• Moldvai , I. , Tóth , G. , Szántay , Cs. Jr. , Kühne , H. , Vedres , A. and Szántay , Cs. 1988 . J. Chem. Res., (S) , : 314
   Google Scholar
• 1988 . J. Chem. Res. (M) , : 2423
   Google Scholar
• 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
   Google Scholar
• Bombardelli , E. , Bonati , A. , Gabetta , G. , Martinelli , E. M. , Mustich , G. and Danielli , B. 1975 . Fitoterapia , 2 : 51
   Google Scholar
• Moldvai , I. , Szántay , Cs. Jr. , Tóth , G. , Vedres , A. , Kálmán , A. and Szántay , Cs. 1988 . Recl. Trav. Chim. Pays-Bas , 107 : 335
   Google Scholar