We describe an enantioselective synthetic route to the leucosceptroid family of natural products that allowed to synthesize several members of this natural product familiy.
The cotton bollworm (Helicoverpa armigera) and the beet armyworm (Spodoptera exigua) are among the most destructive agricultural pests in nature and they affect vegetables and other crops worldwide. Protection against them has been achieved by the use of sex-pheromone traps, insecticides, and transgenic crops. However, resistance to insecticides has developed over the last decade and new chemical agents are necessary to prevent further crop damage from these pests. Leucosceptrum canum Smith (“Bird’s Coca Cola tree”) and Colquhounia coccinea var. mollisa, plants found in China and Nepal, are remarkably resistant to herbivores and pathogens. Extraction and isolation of the trichomes, flowers, and whole leaves recently led to the discovery of novel antifeedant „leucosceptroid“ natural products. So far, no general and practical strategy which allows for the collective synthesis of the leucosceptroid family of natural products was available to the scientific community. Herein, we describe an enantioselective synthetic route to the leucosceptorids that allowed to synthesize several members of this natural product familiy. Additionally, we were able to partially mimic the biosynthetic pathway and the current findings support the hypothesis that two biosynthetic pathways are operative in the plant. The presented results should also serve as an example that, today, total synthesis is capable of providing practical access to a whole natural product family and deliver ample quantities of important intermediates as wells as the target compounds for further biological investigations.
Magauer Group | LMU München, Germany
Thomas Magauer was born in Linz, Austria in 1983. He grew up in Steyr and moved to Vienna in 2002 to study chemistry at the University of Vienna. In 2007, he joined the laboratories of Prof. Johann Mulzer and under his guidance he developed enantioselective syntheses of the complex polyketide kendomycin and the sesquiterpenoid echinopines A and B. After graduating in 2009, he moved to Harvard University, USA, to begin postdoctoral studies with Prof. Andrew G. Myers. At Harvard University he worked on carbohydrates, chiral silicon protecting groups and developed a synthesis of natural and diverse unnatural antiproliferative trioxacarcins. In 2012, he started his independent research as a Liebig-junior research group leader at the LMU Munich. In 2013, he was awarded the Emmy Noether fellowship by the DFG.
Cedric L. Hugelshofer was born in Bern, Switzerland in 1988. He studied chemistry at the University of Basel and joined the group of Prof. Andrew G. Myers at Harvard University, USA, to conduct the research for his Master’s thesis. During this time he worked on the development of a methodology for the synthesis of enantiomerically enriched α-quaternary amino acids using pseudoephenamine as a chiral auxiliary. In summer 2013, he joined the laboratories of Dr. Thomas Magauer for his PhD studies and began working on the total synthesis of antifeedant leucosceptroid natural products.
Klaus Speck was born in Mediasch, Romania in 1987. After moving to Germany in 1990, he grew up in Göppingen, where he recieved his Abitur. While studying Chemistry at the Ludwigs-Maximilliams-Universität München, he spent a research stay in the group of Prof. Stephen Nolan working on the development of new N-heterocyclic carbenes and their application in the Buchwald-Hartwig aryl-amination at the University of St. Andrews. In 2012, he joined the Group of Thomas Magauer for his Master thesis working on the total synthesis of the meroterpenoid Stachyflin. Since 2013, he is a PhD student in the Magauer lab investigation the synthesis of antiviral meroterpenoids and developing novel Au-cataylzed enyne reactions.
Adriana S. Grossmann was born in Tegernsee, Germany in 1989. She studied chemistry at the Ludwigs-Maximilians-Universität München and joined the group of Thomas Magauer to conduct the research for her Master’s thesis. During this time she worked on the development of a methodology for the synthesis of functionalized 3-hydroxybenzoic acids via fragmentation of bicycle[3.1.0]hexan-2-ones. At the beginning of 2014, she began her PhD studies working on the Claisen rearrangement of allyl 1,2-dichlorovinyl ethers for the synthesis of 2,4 dienoic acids.
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