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2014 | Buch

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Development of New Radical Cascades and Multi-Component Reactions

Application to the Synthesis of Nitrogen-Containing Heterocycles

verfasst von: Marie-Helene Larraufie

Verlag: Springer International Publishing

Buchreihe : Springer Theses

Enthalten in: Springer Professional "Wirtschaft+Technik" , Springer Professional "Technik" , Springer Professional "Wirtschaft"

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Über dieses Buch

In this dissertation, Marie-Hélène Larraufie develops original radical and pallado-catalyzed methodologies to enable the synthesis of several classes of bioactive nitrogen-containing heterocycles. New radical cascades employing the N-acylcyanamide moiety offer straightforward routes to quinazolinones and guanidines, as well as new insights into the mechanism of homolytic aromatic substitutions. In parallel, Larraufie expands the scope of visible light photoredox catalysis to the ring opening of epoxides and aziridines, thus providing new sustainable alternatives for the generation of radicals. Furthermore, in a collaborative effort with the Catellani group, the author investigates dual palladium/norbornene catalysis. First, she develops a C-amination coupling variant of the Catellani reaction with unprotected amines which provides an expeditious route to phenanthridines. Then, she examines the influence of the chelating effect on Pd(IV) intermediates reactivity with the help of experimental studies and DFT calculations. The work in this thesis has resulted in numerous publications in high impact journals.The clarity and depth of the experimental section will be useful for students and researchers working in this field.

Inhaltsverzeichnis

Frontmatter

N-acylcyanamides as New Partners in Radical Cascades: Synthesis of Polycyclic Quinazolinones and Guanidines

Chapter 1. Bibliographical Backgrounds

Abstract

The cyanamide moiety consists of a nitrogen atom bearing a nitrile group. When the nitrogen atom is substituted with a carbonyl group, one speaks of N-acylcyanamide. Thanks to its original structure, it possesses unique properties as a building block in organic synthesis, as a ligand in organometallic applications or as an essential function in bioactive compounds. The synthesis and chemical transformations of mono- and disubstituted cyanamides have been reviewed in depth by Nekrasov in 2004, so only the recent literature will be covered in this section.

Marie-Hélène Larraufie

Chapter 2. Results: Developments of New Radical Cascades with N-Acylcyanamides

Abstract

Since radical cascades using cyanamides have been reported only starting from aryl radicals, we have wished to broaden the scope of these cascades. Our objectives were to test the reactivity of alkyl, vinyl and aminyl radicals in this process. Indeed, the use of alkyl and vinyl radical should provide us with a straightforward access to natural and biologically active quinazolinones; while the use of aminyl radicals should afford the first radical synthesis of guanidines.

Marie-Hélène Larraufie

Chapter 3. Supporting Information

Abstract

Reactions were carried out under argon, with magnetic stirring and redistilled solvents. THF and Et₂O were distilled from sodium/benzophenone. CH₂Cl₂, acetonitrile, NEt₃ and t-BuOH were distilled from CaH₂. Benzene and toluene were distilled from sodium/potassium amalgam. 2,2-Azobis(2-methylpropionitrile) (AIBN) was precipitated in acetone at 0 °C.

Marie-Hélène Larraufie

Visible-light Photoreductive Catalysis for an Eco-compatible Generation of Radicals

Frontmatter

Chapter 4. Bibliographical Backgrounds: Generation of Radicals by Visible Light Photoredox Catalysis

Abstract

Visible light has the potential to serve as a sustainable, clean, economical and abundant source of energy. Visible light-induced electron transfer reactions are thus widely used in nature. Photosynthetic organisms absorb visible light by antenna proteins containing chromophores. Subsequent photon-induced electron transfers generate charge-separated states which are used to prepare various high-energy molecules required to fuel organisms. The progressive elucidation of the molecular mechanisms of photosynthesis has raised tremendous hopes that efficient means would be found for artificial conversion of solar energy. Thus, one century ago, Professor Ciamician (University of Bologna), one of the pioneer in photochemistry forecasted: “The photochemical processes, that hitherto have been guarded secret of the plants, will have been mastered by human industry which will know how to make them bear even more abundant fruit than nature, for nature is not in a hurry but mankind is”.

Marie-Hélène Larraufie

Chapter 5. Results: Visible Light-Induced Photoreductive Generation of Radicals from Epoxides and Aziridines

Abstract

Epoxides are readily available and highly valuable radical precursors, as demonstrated by their omnipresence in radical transformations. Several methodologies have been reported so far for their radical ring-opening. Epoxides are particularly prone to reductive ring-opening via one-electron transfer. Lithium 4,4′-di-tert-butylbiphenylid (LDBB) has thus been widely used to generate lithiated radical anions such as 99. This latter is immediately reduced to dianion 100 which can add to various electrophiles.

Marie-Hélène Larraufie

Chapter 6. Supporting Information

Abstract

Reactions were carried out under argon, with magnetic stirring and redistilled solvents. THF and Et₂O were distilled from sodium/benzophenone. CH₂Cl₂, acetonitrile, DMSO, NEt₃ and t-BuOH were distilled from CaH₂. Thin layer chromatography (TLC) was performed on Merck 60 F254 silica gel. Merck Geduran SI 60 Å silica gel (35−70 mm) was used for column chromatography. The melting points reported were measured with a Reichert hot stage apparatus and are uncorrected. IR spectra were recorded with a Bruker Tensor 27 ATR diamant PIKE spectrometer.

Marie-Hélène Larraufie

New developments in Aryl–Aryl Couplings via Palladium/Norbornene Dual Catalysis: Synthesis of Phenanthridines and Phenanthrenes

Frontmatter

Chapter 7. Bibliographical Background: The Ortho Effect in The Catellani Reaction

Abstract

Pallado-catalyzed sequential reactions involving direct C–H bond activations have emerged as powerful tools for rapid access to complex polycyclic scaffolds, starting from simple precursors. In this context, Professor Marta Catellani has pioneered in the mid 1980s the utilization of norbornene in cooperation with palladium to achieve sequential C-halide and C–H activations via the formation of a five-membered alkylaromatic palladacycle.

Marie-Hélène Larraufie

Chapter 8. Results: New Partners for Ortho-Substituted Aryl Iodides in Palladium/Norbornene Cocatalysis

Abstract

As we have seen in part Sect. 7.2, the incorporation of a N-aryl coupling reaction with unprotected amines in a Catellani sequence has never been reported. Only amides, imines and tosylated and acetylated anilines have been used successfully as coupling partners.

Marie-Hélène Larraufie

Chapter 9. Supporting Information

Abstract

Reagents were obtained from commercial sources and used as received. 4-Methoxy-2-methyliodobenzene, 3,4-dimethoxy-2-methyliodobenzene, 4-methoxyiodonaphthalene were prepared according to reported procedures. Reactions were carried out with redistilled solvents. THF and Et₂O were distilled from sodium/benzophenone. CH₂Cl₂, acetonitrile, NEt₃ were distilled from CaH_2.

Marie-Hélène Larraufie

Backmatter

Titel: Development of New Radical Cascades and Multi-Component Reactions
verfasst von: Marie-Helene Larraufie
Verlag: Springer International Publishing
Electronic ISBN: 978-3-319-01324-4
Print ISBN: 978-3-319-01323-7
DOI: https://doi.org/10.1007/978-3-319-01324-4

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