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DOI: 10.1039/A807868H (Paper) Reference Section for: Chem. Commun., 1998, 2639-2640

Formal stereoselective synthesis of (±)-akagerine

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M.-Lluïsa Bennasar, Bernat Vidal, Bilal A. Sufi and Joan Bosch

Abstract

A stereoselective synthesis of pentacyclic dilactam 1, a known precursor of the indole alkaloid akagerine, involving addition of the enolate of 1-acetylindole 2 to 3-acetyl-2-fluoropyridinium salt 3, cyclization of the resultant 1,4-dihydropyridine, elaboration of the (E)-ethylidene substituent and closure of the C ring by Pummerer reaction, is reported.

References

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  12. Selected data for 5: δH(300 MHz, CDCl3) 2.09 (s, 3H, 18-H), 2.32 (dm, J 14, 1H, 14-H), 2.44 (m, 1H, 14-H), 2.81 (m, 1H, 5-H), 2.96 (br d, J 12.8, 1H, 16-H), 3.15 (m, 4H, 6-H, 15-H, 16-H), 3.60 (m, 1H, 5-H), 4.80 (d, J 5.1, 1H, 3-H), 6.16 (s, 1H, 7-H), 7.26–7.33 (m, 7H, Ar), 7.42 (d, J 7.6, 1H, 9-H), 8.13 (d, J 8.2, 1H, 12-H); δC(75 MHz, CDCl3) 18.4 (C-18), 29.3 (C-15), 30.7 (C-6), 32.3 (C-14), 44.4 (C-5), 47.7 (C-16), 56.9 (C-3), 96.7 (C-20), 112.5 (C-7), 115.5 (C-12), 120.6 (C-9), 123.7 (C-10), 125.8 (C-11), 126.3 (Ph), 129.2 (Ph), 129.5 (C-8), 135.0 (Ph), 135.2 (C-2), 138.4 (C-13), 168.9 (C-19), 171.7, 172.7 (C-17, C-21).
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