Catalytic Intramolecular Carbene Transfer Reactions into σ and π Bonds （σ及びπ結合への触媒的分子内カルベン移動反応） March, 2020 Doctor of Philosophy (Engineering) PHAN THI THANH NGA ファン ティ タン ガ Toyohashi University of Technology ACKNOWLEDGEMENTS First and foremost, I would like to express my deep thanks to my supervisor, Professor Dr. Seiji Iwasa, for everything he did for me during my study within four years. Actually, there is no words can express my deep sense of gratitude towards him. I would like to thanks him for his endless support, encouragement, advices and patience throughout my PhD work.
I would like to express Prof. Kazutaka Shibatomi for his investing time and providing interesting and valuable feedback throughout my research period. And I would like to thank to my doctoral committee members, Prof. Shinichi Itsuno for his valuable suggestions.
I am thankful for Dr. Ikuhide Fujisawa for his hospitality and for assisting me with the X- ray measurements. I am very grateful to Mr. Masaya Tone, Mr.
Hayato Inoue, Ms. Huong for their cooperation, suggestion, and valuable discussion throughout my research period. I also would like to acknowledge all the labmates whom I had the pleasure of working with: Dr. Zolzaya and all other research scholars of the department who have been very friendly and helped me in various ways.
I acknowledge all the staff members of the international and educational affairs division at Toyohashi University of Technology for their support during the progress of my graduation steps. I would like to thank all the friends that I have met in Toyohashi: Mona, Hằng, Huế, Bảo, Trinh, Hường, Khôn, Hoài. I really cherish the great time we spent together: the dinner parties, summer barbecues, autumn red leaves, skiing and Tết. With my appreciation and respect, this work would not have been possible without the financial support of the Hitachi Global Foundation, they gave me the chance to study in Japan under their financial support to my work.
I want to thank all the staffs of Faculty of Chemical Engineering, HCMC University of Technology for their supports in the fulfilment of my PhD program. I also acknowledge Prof. Le Thi Kim Phung – director external relations office of HCMC University of Technology for her support and encouragement. i My deepest gratitude is reserved for my family, for having filled my life with every joy, helping me to get through so many gloomy days and lighting up every last corner.
For my parents, my brother Ấn who have always been there for me. Needless to say, they have helped immeasurably to get me to this point in my life. Thank you very much! PHAN THI THANH NGA Department of Applied Chemistry and Life Science Toyohashi University of Technology, 1-1 Tempaku-cho, Toyohashi, Aichi 441-8580 (Japan) E-mail: phanthanhnga@hcmut.vn ii ABSTRACT Keywords: asymmetric synthesis, cyclopropanation, Buchner reaction, Ru(II)-Pheox catalyst. A carbene known as a most active intermediate is complexed with a transition metal, which affords the corresponding metal-carbene complex and catalytically inserts into σ and π bonds of the organic compound.
Even though there are many reports on the carbene transfer process to develop a new approach for the synthesis of medicine and other bioactive compounds, the regio-, stereo- and chemoselective approaches are still limited and remained as the main subject in the field of synthetic organic chemistry. For this background, I developed an efficient catalytic intramolecular carbene transfer reactions by using originally developed ruthenium catalyst into σ and π bonds and successfully applied for the synthesis of γ-lactam ring fused aromatics (oxindoles), γ-lactone ring fused cyclopropanes, and γ-lactam ring fused seven-membered rings via Buchner reaction. Although the ruthenium complex is a newcomer in the field of catalytic carbene transfer reaction, it has emerged as a useful transition metal for the carbenoid chemistry of diazo compounds, besides copper and rhodium. And recently, we have developed a Ru(II)-Pheox complex, which is efficient for carbene transfer reactions, in particular, asymmetric cyclopropanation, N-H insertion, C-H insertion and Si-H insertion reactions.
Therefore, driven by my interests in the catalytic asymmetric carbene transfer reaction and the efficiency displayed by the Ru(II)-Pheox catalyst, I started to explore the asymmetric cyclopropanation, C-H insertion, Buchner reactions of various diazo compounds, which are potentially building blocks and expectant to be applied in pharmaceutical and medicinal fields. In my thesis, Chapter 1 describes the importance of carbene transfer reactions. And a short review of the metal carbene intermediates in C-H insertion, asymmetric cyclopropanations, and Buchner reaction have been also illustrated in this chapter. In addition, the application of metal carbene complexes in the synthesis of biologically-active or natural product-like compounds is also mentioned.
Chapter 2 is for the synthesis of oxindoles. The oxindole ring is prevalent as an important scaffold found in numerous natural products and pharmaceutically active compounds. Over the past few decades, the emerging therapeutic potential of the structural motif of oxindole has encouraged the medicinal chemists to synthesize novel oxindole derivatives. I report Ru(II)-Pheox iii was found to be a highly efficient catalyst for the synthesis of oxindole derivatives in excellent yields.
We developed the efficient synthesis of oxindole derivatives via intramolecular ArCsp2-H insertion reaction of diazo acetamides derived from the corresponding anilines by using Ru(II)- Pheox catalyst. The reaction proceeds smoothly under mild conditions, providing the corresponding oxindole derivatives in excellent yield (up to 99%). No other side reactions related to metal-carbene reactivity such as dimerization, aromatic ring expansion and Csp3-H on amide nitrogen insertion reaction were observed. On the other hand, the cyclopropane subunit is also present in many biologically important compounds and it shows a large spectrum of biological properties.
Transition metal-catalyzed cyclopropanation involving carbene intermediate is powerful and useful methods for constructing important substructures of targeted molecules, and therefore they have been extensively studied for the past couple of decades. Thus, Chapter 3 presents the development of asymmetric catalysts based on Ru(II)-Pheox complexes, I developed a new series of Ru-Colefin(sp2) bond-containing organometallic complexes and successfully applied them to the catalytic asymmetric inter- and intramolecular cyclopropanations, which are carbene transfer reaction. It is noteworthy that high yields and stereoselectivity were achieved for trans-cyclopropane carboxylates even with a low catalyst loading. Catalytic asymmetric cyclopropanations of diazoesters with olefins in the presence of the Ru-Colefin(sp2)-phenyloxazoline complexes proceeded smoothly to give the corresponding optically active cyclopropanes in high yields, with a trans/cis ratio 97/3 to >99/1 and 97% to >99% ee (trans).
The enantioselectivities were affected by the geminal substituent on the Ru-Colefin (sp2) bond; the highest enantioselectivities were obtained when using Ru(II)-Prox catalyst with no substituent at the germinal position of the metal. Furthermore, medium ring-containing organic molecules, such as seven-membered rings, are also the cornerstone of many bioactive natural compounds such as guaiane sesquiterpenes, guaianolide sesquiterpene lactones. However, there are few reports on their synthesis. Thus, the development of an efficient method to prepare these scaffolds has attracted a significant amount of research attention.
This unique strategy toward seven-membered carbocycles has been utilized in natural product synthesis. In Chapter 4, I report the development of an intramolecular Buchner reaction of a variety of N-benzyl diazoamide derivatives in the presence of a chiral Ru(II)–Pheox catalyst. The aromatic rings are converted into the corresponding γ-lactam ring fused seven- membered ring system with high regio- and stereoselectivity. A variety of γ-lactam fused 5,7- iv bicyclic-heptatriene derivatives have been prepared from diazoacetamides in up to 99% yield with high enantioselectively (up to 99% ee) using a chiral Ru(II)-Pheox catalyst under mild reaction conditions.
In conclusion, Chapter 5, the Ru(II)−Pheox catalyzed C-H insertion reaction and asymmetric Buchner reaction proved to be the efficient and straightforward methods for the preparation of oxindole and seven-membered ring which are important intermediates in the synthesis of many biologically active compounds. Moreover, we have successfully designed and synthesized a novel Ru-Prox type catalyst. This catalyst showed excellent reactivities and selectivities in asymmetric cyclopropanation reactions. And it is expected to provide many further opportunities in asymmetric catalysis.
And in Chapter 6, all the experimental and analytical data as the evidence for Chapter 2 to 4 are described. iii LIST OF SCHEMES………………………………………………………….… x LIST OF FIGURES…………………………………………………………….……… xii LIST OF TABLES…………………………………………………………….… xiii LIST OF ABBREVIATIONS……………………………………………………. xv CHAPTER 1: Introduction 1. The history of carbenes………………………………….
Carbene-metal bond formation…………………………………………. Fischer carbene complexes………………………………………. Schrock carbene complexes…………………………. Generation of carbene………………………….
Properties of α-diazo carbonyl compounds……………………………. Reactivity of α-diazo carbonyl compounds………………. Transition-metal-catalyzed aromatic C-H insertion reactions……………. Intermolecular aromatic C-H insertion reactions.
Intramolecular aromatic C-H insertion reactions………. Simmons–Smith cyclopropanation…………. Transition-metal-catalyzed decomposition of diazoalkanes. The history of Buchner reaction………………………….
Transition-metal-catalyzed intramolecular Buchner reaction…………. Buchner reaction vs C-H insertion. Rhodium catalyzed intramolecular Buchner reaction…………. Copper catalyzed intramolecular Buchner reaction…………….
Synthesis bioactive compounds by intramolecular Buchner reaction………. 31 CHAPTER 2: Highly efficient synthesis of oxindole derivatives via catalytic intramolecular C-H insertion reactions of diazoamides 2. Results and discussions………………………. Catalyst loading and solvent screening for catalytic intramolecular C-H insertion reactions of diazoamides.
Ru(II)-pheox catalyzed intramolecular C-H insertion reactions of diazo- amides. 39 CHAPTER 3: Synthesis of a new entries of chiral ruthenium complexes containing Ru- Colefin(sp2) bond and their application for catalytic asymmetric cyclopropanation reactions 3. Results and discussions……………………. Preparing the ruthenium complexes.
Ruthenium complexes containing Ru-Colefin(sp2) bond catalyzed inter molecular cyclopropanation………………….1 Catalyst screening and optimization conditions for the catalytic intermolecular cyclopropanation. The substrate scope for the catalytic intermolecular cyclo- propanation reaction. Ruthenium complexes containing Ru-Colefin(sp2) bond catalyzed intra molecular cyclopropanation…………………….1 Catalyst screening and optimization conditions for the catalytic intramolecular cyclopropanation. The substrate scope for the catalytic intramolecular cyclo propanation reaction.……… 48 CHAPTER 4: Highly stereoselective intramolecular buchner reactions of diazo acetamides catalyzed by Ru(II)-Pheox complex 4.
Results and discussions……………………. Catalyst screening for intramolecular asymmetric Buchner reaction………. Solvent screening for intramolecular asymmetric Buchner reaction. Ru(II)-Pheox catalyzed intramolecular Buchner .…… 56 CHAPTER 5: Conclusion 57 CHAPTER 6: Experimental analytical data 6.
Experimental analytical data for chapter 2………………. Procedure for the synthesis of diazoacetamides…………. Analytical data for diazoacetamides………………. General procedure for the intramolecular C-H insertion reaction of diazo acetamides by using Ru(II)-Pheox catalyst………………….
Analytical data for the intramolecular C-H insertion reaction of diazo acetamides by using Ru(II)-Pheox catalyst……………………. Experimental analytical data for chapter 3………………. General procedure for catalytic asymmetric intramolecular cyclopropanation reaction…………. Analytical data for asymmetric intermolecular cyclopropanation reaction products………………….
Experimental analytical data for chapter 4………. Preparation of diazoacetamides. Analytical data for diazoacetamides……………. General procedure for catalytic asymmetric intramolecular Buchner reaction of diazoacetamides.
Analytical data for asymmetric intramolecular Buchner reaction products…. 76 IR SPECTRAL DATA………….… 85 NMR SPECTRAL DATA………….… 165 ix LIST OF SCHEMES Scheme 1. Generation of the first stable radical. Synthesis of tropolone-derivatives via the insertion of a methylene intermediate.
Alkene cyclopropanation via methylene intermediate. Metal-carbon bonding in Fischer carbene complexes…. Metal-carbon bonding in Schrock carbene complexes. Generation of carbene.
The resonance structures of α-diazo carbonyls. Reactivity of α-diazo carbonyls. Copper-catalyzed intermolecular aromatic substitution reaction…………. Gold-catalyzed reaction of EDA with toluene…….
Catalyzed azacycle-directed intermolecular aromatic C-H functionalization. Rhodium(II)-catalyzed aromatic substitution reactions of α-diazo-β-keto esters……………………………………. Titanium BINOLate-catalyzed enantioselective intramolecular aromatic C-H functionalization……………………………………. Possible mechanisms for the Simmons–Smith reaction…………….
Accepted catalytic cycle for the carbenoid cyclopropanation reaction……. Mechanism of cobalt-porphyrin catalysis……………. Copper-bisoxazoline-catalyzed cyclopropanation of some diazoalkanes…. Cyclopropanation of styryldiazoacetates…………….
Enantioselective cyclopropanation with α-diazopropionate………………. Enantioselective synthesis of spirocyclopropyloxindoles…………………. Asymmetric cyclopropanation catalyzed by a rhodium(I) complex………. Asymmetric cyclopropanation of 1-tosyl-3-vinylindoles……………….
Ru(II)-pheox catalyzed asymmetric cyclopropanation of terminal alkenes. The Buchner reaction. Predominance of norcaradiene. Stabilization of norcaradiene.
Buchner reaction vs C-H insertion. Copper and rhodium catalyzed intramolecular Buchner reactions…. Rhodium catalyzed intramolecular Buchner reactions…………………. Buchner reactions of cyano-substituted diazoketones………………….
Enantioselective rhodium-catalyzed intramolecular Buchner reaction……. Enantioselective Copper-catalyzed intramolecular Buchner reaction…. Formal synthesis of (±)-confertin……………………………………. Synthesis of harringtonolide…………………………………….
Synthesis of gibberellin derivatives……………………………………. Transition metal catalyzed C-H insertion reaction of diazoacetamides…. The efficiency of Ru(II)-Pheox in the synthesis of oxindole derivatives and their spirocyclopropanation …………………. Intramolecular C-H insertion reaction of diazoacetamide 53g catalyzed by Ru(II)-Pheox………………………………………………………………… 37 Scheme 39.
Plausible mechanism of intramolecular C-H insertion reactions of diazo amides catalyzed by Ru(II)-Pheox……………. Procedure for the synthesis of a series of Ru(II) complexes………………. Synthesis of chiral ruthenium complexes containing Ru-Colefin(sp2) bond… 41 Scheme 42. Planarity of the substituent on β position of Ru-C(sp2) bond…………….
Transition metal catalytic carbene transfer reaction of diazoacetamides….