Arbeitskreis Lindel

Marine Naturstoffe - Bausteine des Lebens

Have you thought about organic synthesis lately?


Am Mittwoch, den 28.06.2017 findet ab 16:15 der Tag der Chemie 2017 im Hagenring 30 (HR 30.1) statt. Nach einem spannenden Vortragsprogramm mit Beiträgen aus der Anorganischen, Organischen und Technischen Chemie gibt es ein Sommerfest mit Bier und Spanferkel. Studierende, Doktoranden, Mitarbeiter und Professoren sind herzlich willkommen!

Programm


Aktuelles Gruppenbild vom Arbeitskreis Lindel
 

Aktuelle Publikationen:

J.-N. Schäckermann, T. Lindel, "Synthesis and Photooxidation of the Trisubstituted Oxazole Fragment of the Marine Natural Product Salarin C", Org. Lett. 2017, 19, 2306-2309.

 
 
Inhalt:
The eastern section of the macrocyclic marine natural product salarin C from the sponge Fascaplysinopsis sp. was synthesized employing a halogen dance reaction to assemble the trisubstituted oxazole moiety. The synthesis was inspired by Kashman’s hypothesis on the biomimetic oxidation of salarin C to salarin A. Clean conversion to the triacylamine partial structure of salarin A occurred on treatment with photochemically generated singlet oxygen. Thus, a Wasserman-type oxidative rearrangement is chemically possible in this case.

N. E. Kanitz, T. Lindel, Photoreactivity of monofluorinated 2-azidobenzimidazoles towards carboxylic acids A", Z. Naturforsch. 2016, 71b, 1287–1300.

 
 
Inhalt:
Aiming at the development of new photolabeling agents, the synthesis and photoreactivity of all monofluorinated derivatives of 2-azido-1-methylbenzimidazole are described. In the case of 4-, 5-, or 7-fluorination, irradiation in the presence of carboxylic acids (300 nm, Rayonet) afforded the monofluorinated 2-amino-6-acyloxybenzimidazoles in a regioselective manner, presumably after conversion of the initially formed nitrene to the N-cyanodiazaxylylene. Incorporation of chloride was also possible, and yields were comparable to those observed for the non-fluorinated parent compound. When blocking the reactive 6-position by a fluoro substituent, the title reaction was not possible. The analysis of the 19F NMR chemical shifts of the 5- and 7-monofluorinated products allowed the distinction between carboxylates and other nucleophiles.

N. Marsch, M. Kock, T. Lindel, Study on the synthesis of the cyclopenta[f]indole core of raputindole A", Beilstein J. Org. Chem. 2016, 12, 334–342.

 
 
Inhalt:
The raputindoles from the rutaceous tree Raputia simulans share a cyclopenta[f]indole partial structure the synthesis of which is subject of this investigation. An efficient route to a series of 1,5-di(indol-6-yl)pentenones was developed via Mo/Au-catalyzed Meyer–Schuster rearrangement of tertiary propargylic alcohol precursors. However, none of the enones underwent the desired Nazarov cyclization to a cyclopenta[f]indole. More suitable were 6-hydroxyallylated indolines which gave good yields of cyclopenta[f]indolines after treatment with SnCl4, as soon as sterically demanding β-cyclocitral adducts were reacted. Most successful were Pt(II) and Au(I)-catalyzed cyclizations of N-TIPS-protected indolin-6-yl-substituted propargylacetates which provided the hydrogenated tricyclic cyclopenta[f]indole core system in high yield.