Late stage functionalization of unactivated C-H bonds in terpenes – a fruitful field for free radical chemistry
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Bazele materiale ale vieții. Biochimie. Biologie moleculară. Biofizică (655)
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KULCIŢKI, Veaceslav, CAZACU, Cătălina, MORĂRESCU (CHETRARU), Olga, PRUTEANU, Elena, GÎRBU, Vladilena, UNGUR, Nikon, RENAUD, Philippe. Late stage functionalization of unactivated C-H bonds in terpenes – a fruitful field for free radical chemistry. In: New frontiers in natural product chemistry.: A destiny on the altar of research. Dedicated to academician Pavel Vlad, Ed. 6, 21 mai 2021, Chișinău. Chișinău, Republica Moldova: Tipografia "Artpoligraf", 2021, Ediția 6, p. 20. ISBN 978-9975-3336-7-2. DOI: https://doi.org/10.19261/nfnpc.2021.ab13
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New frontiers in natural product chemistry.
Ediția 6, 2021
Conferința " New frontiers in natural product chemistry."
6, Chișinău, Moldova, 21 mai 2021

Late stage functionalization of unactivated C-H bonds in terpenes – a fruitful field for free radical chemistry

DOI: https://doi.org/10.19261/nfnpc.2021.ab13
CZU: 547.597.057+577.334

Pag. 20-20

Kulciţki Veaceslav1, Cazacu Cătălina1, Morărescu (Chetraru) Olga1, Pruteanu Elena2, Gîrbu Vladilena1, Ungur Nikon1, Renaud Philippe2
 
1 Institute of Chemistry,
2 University of Bern
 
Proiect:
20.80009.8007.03 Noi substanțe cu potențial preventiv și terapeutic în baza compușilor naturali de origine vegetală și a matodelor moderne de sinteză organică
 
Disponibil în IBN: 28 mai 2021


Rezumat

Terpenoids are a large group of natural products with a broad structural diversity which are biosynthetically produced in living cells over a multistep sequence of events. The expansion of terpenoids structures, which are based on similar elementary building blocks, is due to an array of isomerizations and selective functionalizations/degradations of isoprenic chains, leading to cycles, chiral centers and heteroatomic functional groups. These transformations can be hardly reproduced synthetically and free radical processes represent an efficient tool to trigger both cyclization and functionalization events. The current communication will present our results on application of free radical chemistry in order to achieve selective late stage C-H functionalizations in higher terpenes. Radical relay processes proved efficient for remote functionalization of sesterterpenes of scalarane family. An alternative approach relates to the well-known Atom Transfer Radical Addition (ATRA), which turned out to be an excellent opportunity for long range remote functionalization under different reaction settings. It occurs through a parallel Hydrogen Atom Transfer (HAT), which allows free radical migration to both primary and tertiary positions. Different HAT sequences have been observed, including an unprecedented 3-fold 1,5-HAT, leading to a distal functionalization of epi-manoyloxide. Application of visible light fotoredox catalysis showed compatibility with ATRA-HAT sequence, demonstrating the free radical character of fotoredox processes. The steric factors have been found to be crucial for a successful application of ATRA-HAT strategy. Functionalized derivatives of both manoyloxide and epi-manoyloxide have been obtained.