| 1. |
- Deliaval, Marie, 1993-
(författare)
-
Synthesis of chiral allyl and propargyl boronates by organocatalytic carbene insertion to carbon-boron bonds
- 2023
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis describes the development of a novel organocatalytic method for the synthesis of chiral allyl- and propargyl- organoboron compounds with high enantioselectivity. These organoboron species are versatile building blocks in asymmetric synthesis.We have developed a new efficient homologation method of alkenyl boronic acids. This reaction affords enantiomerically enriched trifluoromethylated allylboronates. These organoboron species were used in allylboration of carbonyl compounds, imines and indole derivatives. The reactions proceeded with a remarkably high stereoselectivity to give homoallylic alcohols and amines. In addition, the chiral allylboronic acids can be oxidized to the corresponding alcohols with retention of the configuration.Based on the homologation of alkenylboronic acids a new three-component reaction is developed. This reaction involved coupling of alkynyl boronates, diazo compounds and ketones in the presence of chiral organocatalysts. This coupling proceeds with high selectivity under mild reaction conditions. The three-component coupling reaction is based on a homologation–allylboration sequence. The process is suitable for synthesis of CF3- and TMS-substituted allenols with excellent diastereo- and enantioselectivity. Application of aromatic, cyclic and non-cyclic ketones leads to formation of chiral tertiary allenols.We have also studied the effects of boronic acid esters on the outcome of the homologation reaction. It was found that a facile transesterification of the boronate precursors with the organocatalyst, BINOL derivatives, is a prerequisite of the successful homologation reaction.
|
|
| 2. |
|
|
| 3. |
- Aydin, Juhanes, 1978-
(författare)
-
Novel Pincer Complex-Catalyzed Transformations : Including Asymmetric Catalysis
- 2009
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis is focused on the development of new pincer complex-catalyzed transformations. Optimization of the catalytic properties (fine-tuning) was directed to increase the catalytic activity as well as the chemo-, stereo- and enantioselectivity of the complexes. This was achieved by varying the heteroatoms in the terdentate pincer ligand, by changing the electronic properties of the coordinated aryl moiety and by implementing chiral functionalities in the pincer complexes. In the cross-coupling reaction of vinyl epoxides and aziridines with organoboronic acids the chemoselectivity of the reaction could be increased by employment of pincer complexes instead of commonly used Pd(0) catalysts. Furthermore, the introduction of a methoxy substituent in the aromatic subunit of the complex considerably increased the activity of the pincer complex catalyst. Fine-tuning of the enantioselectivity in electrophilic allylation reactions was achieved by using a wide variety of new BINOL- and biphenanthrol-based pincer complexes. The highest enantioselectivity (85% ee) was obtained by applying biphenanthrol-based pincer complexes. Stereoselective pincer complex-catalyzed condensation of sulfonylimines with isocyanoacetate could be achieved under mild reaction conditions. By application of chiral PCP catalysts, 2-imidazolines could be obtained with up to 86% ee. A new pincer complex-catalyzed C-H bond functionalization based reaction between organonitriles and sulfonylimines affords homoallylic amines and beta-aminonitriles in high yields. The asymmetric version of this process affords beta-aminonitriles with up to 71% ee. In the last chapter, a pincer complex-catalyzed redox coupling reaction is described. In this highly regio- and stereoselective process the integrity of the pincer catalysts is fully retained. This catalytic reaction proceeds with a high level of functional group tolerance, as allylic acetate and aryl halide functionalities are retained.
|
|
| 4. |
- Cortés González, Miguel Ángel, 1992-
(författare)
-
Development of new Fluorination Methods Directed to Fluorine-18 Labelling
- 2019
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis deals with the development of new fluorination reactions and their application to fluorine-18 labelling. Fluorine-18 labelled compounds are employed as tracers in Positron Emission Tomography (PET), which is a powerful non-invasive imaging method in medical diagnostics.The first part of this thesis focuses on the development of a late-stage halogen exchange-based fluorination method for the synthesis of trifluoromethylated molecules. The first project in this area relies on the application of a copper(I)-based fluorinating reagent to furnish trifluoroacetates, trifluorotoluenes and trifluoroacetamides. The second project involves the translation of this methodology into the fluorine-18 labelling of tertiary and secondary trifluoroacetamides. The targeted substrates were labelled in high radiochemical yield and high molar activity using [18F]Bu4NF as fluorine source in the presence of an organic activator.In the second part, the development of electrophilic fluorination reactions using a hypervalent iodine-based reagent is discussed. The first project in this area addresses the development of an electrophilic fluorine-18 fluorination reagent: [18F]fluoro-benziodoxole. The utility of this reagent was demonstrated in the labelling of [18F]fluoro-benzoxazepines. In the second project, the same [18F]fluoro-benziodoxole reagent was used in the rhodium-mediated synthesis of α-[18F]fluoroethers. High molar activities were obtained in these electrophilic labelling processes. In the third project, the fluorine-19 analog fluoro-benziodoxole was used in the palladium-catalyzed iodofluorination of allyl benzenes, styrenes and cycloalkenes. Both iodine and fluorine atoms in the product arise from the same reagent.
|
|
| 5. |
- Gerdin, Martin, 1976-
(författare)
-
Silaborations of Unsaturated Compounds
- 2008
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis deals with the development of transition metal-catalyzed silaborations of 1,3-dienes and 1,6-enynes. The first part of the thesis describes the development of the enantioselective 1,4-silaboration of 1,3-cyclohexadiene. A number of chiral metal-ligand complexes were evaluated. Up to 82% enantiomeric excess was obtained using a catalyst system derived from Pt(acac)2 and a phosphoramidite ligand. The product formed was employed in allylborations of aldehydes, giving homo-allylic alcohols in good yields with good to moderate diastereoselectivity. In attempts to widen the scope of silaborations to include acyclic, terminally substituted 1,3-dienes, products from H-B exchange with, and H-Si addition to, the dienes were obtained. The second part describes the development of silaborative carbocyclization of 1,6-enynes. A Pd N-heterocylic carbene complex was found to be effective for the silaborative carbocyclization of unsubstituted enynes, giving the products in good to excellent yields. Employing terminally substituted enynes resulted in low or no yields. The last part describes investigations into the reaction mechanisms of the processes developed in the first part. It was found that the silylborane undergoes oxidative addition to a Pt(0) complex generated from Pt(acac)2 and DIBALH. After insertion of 1,3-cyclohexadiene into the Pt-B bond a π-allyl complex was observed experimentally. In the addition of silylborane to acyclic, terminally substituted, 1,3-dienes it was shown by deuterium labeling experiments that one diene loses a hydride via H-B exchange and that this hydride is then added to another diene via H-Si addition. A reaction mechanism was proposed for this process.
|
|
| 6. |
- Ilchenko, Nadia O., 1989-
(författare)
-
Novel Applications of Benziodoxole Reagents in the Synthesis of Organofluorine Compounds
- 2017
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis concerns method development of new synthetic routes by applying electrophilic hypervalent iodine reagents, such as trifluoromethyl-benziodoxole (Togni reagent) and fluoro-benziodoxole. The first project involved the addition of an oxygen moiety and trifluoromethyl group across double and triple bonds (both groups derived from the hypervalent iodine reagent). We observed that electron donating substituents on the aromatic ring of the substrate accelerated the oxytrifluoromethylation reaction. This transformation was further expanded to halo-trifluoromethylation reaction of a vinyl silane substrate. We also developed a copper mediated cyanotrifluoromethylation reaction, which was accelerated by PCy3 additive. This transformation allowed for the creation of two new C-C bonds in a single addition reaction. The direct C-H trifluoromethylation reaction of quinones was achived using the Togni-reagent in the presence of B2pin2 additive. The intriguing additive effects of both B2pin2 and PCy3 inspired us to examine the mechanism of these transformations.Fluoro-benziodoxole is the fluoroiodane analogue of the trifluoromethylating Togni reagent. We developed a AgBF4 mediated geminal difluorination of styrenes using this fluoroiodine reagent. In this process one fluorine atom came from the fluoroiodane, while the other fluorine was derived from the tetrafluoroborate ion. A similar approach was applied for the 1,3-oxyfluorination and difluorination of cyclopropanes. Similarly, this fluorinative ring opening of unactivated cyclopropanes involved the introduction of an electrophilic fluorine atom from the fluoroiodane reagent and a nucleophilic one from the tetrafluoroborate ion. This reaction was extended to synthesis of 1,3-oxyfluorinated products. When alkenes reacted with the fluoro-benziodoxole reagent in the presence of palladium catalyst the iodofluorination reaction occurred. Both the iodine and fluorine atoms were derived from the fluoroiodane reagent. The iodofluorination reaction with disubstituted and cyclic alkenes proceeded with high regio- and stereoselectivity.
|
|
| 7. |
- Janson, Pär, 1984-
(författare)
-
Oxidative Trifluoromethylation and other Functionalization Reactions of Alkenes and Alkynes
- 2014
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis concerns the use of various potent oxidants in organic synthesis. The main focus is directed at selectively introducing trifluoromethyl groups into compounds containing double or triple bonds. All reactions proceed under mild conditions and can in most cases be performed on the bench-top.We have developed three different procedures for transformations of activated alkenes and alkynes as well as quinones. In paper I the selective introduction of a trifluoromethyl group together with an oxygen functionality to double and triple bonds is demonstrated.Paper II is focused on the related chemoselective cyanotrifluoromethylation in which a cyano group is added instead of the oxygen functionality.Paper III describes a new procedure for C–H trifluoromethylation of quinones. Our studies on the mechanistic aspects of the above reactions are described in Paper IV. In these studies we investigated the ligand and substituent effects in Cu-catalyzed reactions.Paper V is focused on a conceptually new palladium-catalyzed allylic C–H acyloxylation of olefins under oxidative conditions. The procedure uses an inexpensive, safe and environmentally benign oxidant, sodium perborate, which is activated with acetic anhydride.
|
|
| 8. |
- Jonker, Sybrand, 1992-
(författare)
-
Synthesis of Organoboronic Acids and Applications in Asymmetric Organocatalysis
- 2021
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Allyl- and allenylboronic acids are valuable reagents in organic synthesis due to their configurational stability and high reactivity. Few allyl- and allenylboronates are commercially available. Therefore, both the preparation and synthetic application of these organoboronic acids are subjects of study. A copper-catalyzed method for the synthesis of tetrasubstituted allenylboronic acids is presented in this thesis. Several enantioselective applications of these allenylboronic acids are presented, including the synthesis of chiral α-amino acid derivatives. Applications of γ,γ-disubstituted allylboronic acids in asymmetric organocatalysis are also presented in this thesis. Varying the E-Z geometry of the allylboron reagents allowed for stereodivergent synthesis of products bearing up to three stereocenters. A common element in the asymmetric methodologies described in this thesis is the application of BINOL-type organocatalysts. The most notable example is the methodology developed for the preparation of α-chiral allylboronic acids via asymmetric homologation of olefinic boronic acids. The resulting chiral boronic acids are of high synthetic interest, which is demonstrated by the wide variety of synthetic applications including allylboration, oxidation, and a purification sequence leading to isolated α-chiral allylboronic acids.
|
|
| 9. |
- Lübcke, Marvin, 1990-
(författare)
-
Bifunctionalization of Small Organic Molecules Based on Fluorine Incorporation
- 2020
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The dissertation work that is summarized in this thesis describes novel syntheses of organofluorine compounds with a broad coverage of different fluorine-containing motifs.Chapter 2.1 covers works on the exploration of new trifluoromethylthiolating reactions of diazocarbonyl compounds. A rhodium-catalyzed oxy-trifluoromethylthiolation reaction enabled the synthesis of densely functionalized carbonyl compounds. Different oxygen nucleophiles, for instance alcohols, ethers and acetals underwent this transformation.A zinc triflimide mediated three-component reaction established an arylation-trifluoromethylthiolation of diazocarbonyl compounds. In situ generation of triarylboranes was rendered most effective for the arylation event. Both procedures made use of the high reactivity of a recently developed electrophilic trifluoromethylthiolating reagent.The second chapter (2.2) is dedicated to the late-stage construction of trifluoromethyl motifs. By means of halide exchange, nucleophilic fluoride from a copper(I)-complex could be used to exchange bromide with fluoride in the α-position to carbonyl groups as well as in benzylic positions.The third chapter (2.3) covers the development of an enantioselective fluorocyclization reaction. In situ generated aryliodine(III)-fluoride species were used as organocatalysts. Through this oxidative olefin difunctionalization reaction, quaternary C-F stereogenic centers could be constructed with high enantiomeric excesses. DFT calculations enabled deeper understanding of the mechanism and the origin of stereoselectivity.
|
|
| 10. |
- Olsson, Vilhelm, 1982-
(författare)
-
Development of New Synthetic Routes to Organoboronates by Catalytic Allylic Substitution and C-H bond Functionalization
- 2009
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis describes the development of new catalytic methods for the synthesis and application of organometallic reagents, mainly focusing on allylboronic acid derivatives. Thus, palladium pincer-complex catalysis has been applied for extending the scope of palladiumcatalyzed borylation reactions in the synthesis of regio- and stereodefined functionalized allylboronic acid derivatives. These novel allylboronic acids were also employed as substrates in palladium catalyzed regioselective coupling reactions with iodobenzenes. We have also developed a new one-pot sequence based on preparation of allyl- and vinylboronates via catalytic carbon-hydrogen bond activation/borylation reactions. The synthetic scope of the reaction as well as mechanistic studies on the borylation process are presented. Finally, the synthesis of new chiral palladium pincer-complexes is described. These species were employed as catalysts in asymmetric electrophilic allyation of imines.
|
|
