Iron-mediated Synthesis of the Antiostatins

• Main Author: Knott, Kerstin
• Other Authors: Technische Universität Dresden, Fakultät Mathematik und Naturwissenschaften
• Format: Doctoral Thesis
• Language: English
• Published: Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden 2009
• Subjects: Antiostatin; Carbazole Alkaloids; Transition metal mediated carbazole synthesis; Carbazol Alkaloide; Übergangsmetall vermittelte Carbazolsynthese; ddc:540; rvk:VK 8627
• Online Access: http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1237582907592-42405; http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1237582907592-42405; http://www.qucosa.de/fileadmin/data/qucosa/documents/825/1237582907592-4240.pdf

Within this thesis the first total syntheses of eight biologically active natural products from the family of carbazole alkaloids, antiostatins A1 to A4 and B2 to B5, were established. Spectroscopic data of the synthesised natural products are in good agreement with the isolated antiostatins from Streptomyces cyaneus 2007-SV1, which confirms the molecular structures assigned to the natural products. The total synthesis of the antiostatins A1 to A4 and B2 to B5 were achieved employing the iron-mediated synthesis to form the carbazole nucleus from a cyclohexadienylium iron salt and appropriate arylamines. This transition metal-mediated approach could be applied to all antiostatins in excellent yields. The antiostatins A1-4 and B2-5 represent the first carbazole alkaloids with an acetamide or substituted biuret chain. Introduction of the sophisticated substituents proceeded selectively on C-4 in high yields. Antiostatins A1 to A4 and B2 to B5 could be synthesised over eight steps from a tricarbonyliron-coordinated cyclohexadienylium salt. The overall yields are in the range of 31 – 63%.