Nobumasa Kamigata

Bio: Nobumasa Kamigata is an academic researcher from Tokyo Metropolitan University. The author has contributed to research in topics: Ruthenium & Aryl. The author has an hindex of 26, co-authored 217 publications receiving 2395 citations. Previous affiliations of Nobumasa Kamigata include Fukuoka University & University of Electro-Communications.

Novel perfluoroalkylation of alkenes with perfluoroalkanesulphonyl chlorides catalysed by a ruthenium(II) complex

Abstract: The perfluoroalkylation of acyclic and cyclic alkenes by perfluoroalkanesulphonyl chlorides 1 has been investigated in the presence of a ruthenium(II) catalyst. The addition reactions proceeded smoothly, with extrusion of sulphur dioxide, in alkenes possessing either an electron-donating or an electron-withdrawing group, at 120 °C to give the corresponding chloroperfluoroalkylated compounds in high yield.

Reaction of trifluoromethanesulphonyl chloride with alkenes catalysed by a ruthenium(II) complex

Abstract: The reaction of trifluoromethanesulphonyl chloride with alkenes in the presence of dichlorotris(triphenylphosphine)ruthenium(II) gives 1:1 adducts with extrusion of sulphur dioxide.

Perfluoroalkylations of nitrogen-containing heteroaromatic compounds with bis(perfluoroalkanoyl) peroxides

Abstract: Perfluoroalkylations of nitrogen-containing heteroaromatic compounds with bis(perfluoroalkanoyl) peroxides were studied. Bis(trifluoroacetyl) peroxide, bis(heptafluorobutyryl) peroxide, and bis(pentadecafluoro-octanoyl) peroxide were found to be useful and effective reagents for perfluoromethylations, perfluoropropylations, or perfluoroheptylations of pyrrole and its derivatives, while these peroxides could not be applied for the perfluoroalkylations of pyridine or imidazole. For the perfluoroalkylations with the peroxides, electron transfer from the substrate to the peroxide, which affords a perfluoroalkyl radical and a cation radical of the substrate in a solvent cage, is proposed. In pyrroles, since the delocalization of the N lone pair to π-systems lowers the nucleophilicity of the N lone pair and increases the electron density at the π-orbital, the electron transfer readily occurred and perfluoroalkylated pyrroles were obtained in good yield and regioselectively. However, nucleophilic attack of the N lone pair to the O–O bond of the peroxide was superior to the electron transfer in pyridine or imidazole of which the N lone pairs are very nucleophilic.

Reactions of arenesulfonyl chlorides with olefins catalyzed by a ruthenium(II) complex

Abstract: Etude des reactions des chlorures d'arenesulfonyle avec des styrene, chloro-4 styrene et phenyl-2 propene. Obtention de sulfones vinyliques

The heck reaction as a sharpening stone of palladium catalysis.

Abstract: s, or keywords if they used Heck-type chemistry in their syntheses, because it became one of basic tools of organic preparations, a natural way to

Aryl-aryl bond formation by transition-metal-catalyzed direct arylation.

Abstract: The biaryl structural motif is a predominant feature in many pharmaceutically relevant and biologically active compounds. As a result, for over a century 1 organic chemists have sought to develop new and more efficient aryl -aryl bond-forming methods. Although there exist a variety of routes for the construction of aryl -aryl bonds, arguably the most common method is through the use of transition-metalmediated reactions. 2-4 While earlier reports focused on the use of stoichiometric quantities of a transition metal to carry out the desired transformation, modern methods of transitionmetal-catalyzed aryl -aryl coupling have focused on the development of high-yielding reactions achieved with excellent selectivity and high functional group tolerance under mild reaction conditions. Typically, these reactions involve either the coupling of an aryl halide or pseudohalide with an organometallic reagent (Scheme 1), or the homocoupling of two aryl halides or two organometallic reagents. Although a number of improvements have developed the former process into an industrially very useful and attractive method for the construction of aryl -aryl bonds, the need still exists for more efficient routes whereby the same outcome is accomplished, but with reduced waste and in fewer steps. In particular, the obligation to use coupling partners that are both activated is wasteful since it necessitates the installation and then subsequent disposal of stoichiometric activating agents. Furthermore, preparation of preactivated aryl substrates often requires several steps, which in itself can be a time-consuming and economically inefficient process.

Transition-metal-catalyzed direct arylation of (hetero)arenes by C-H bond cleavage.

Abstract: The area of transition-metal-catalyzed direct arylation through cleavage of CH bonds has undergone rapid development in recent years, and is becoming an increasingly viable alternative to traditional cross-coupling reactions with organometallic reagents In particular, palladium and ruthenium catalysts have been described that enable the direct arylation of (hetero)arenes with challenging coupling partners—including electrophilic aryl chlorides and tosylates as well as simple arenes in cross-dehydrogenative arylations Furthermore, less expensive copper, iron, and nickel complexes were recently shown to be effective for economically attractive direct arylations

Introduction of Fluorine and Fluorine-Containing Functional Groups

Abstract: Over the past decade, the most significant, conceptual advances in the field of fluorination were enabled most prominently by organo- and transition-metal catalysis. The most challenging transformation remains the formation of the parent C-F bond, primarily as a consequence of the high hydration energy of fluoride, strong metal-fluorine bonds, and highly polarized bonds to fluorine. Most fluorination reactions still lack generality, predictability, and cost-efficiency. Despite all current limitations, modern fluorination methods have made fluorinated molecules more readily available than ever before and have begun to have an impact on research areas that do not require large amounts of material, such as drug discovery and positron emission tomography. This Review gives a brief summary of conventional fluorination reactions, including those reactions that introduce fluorinated functional groups, and focuses on modern developments in the field.

Dynamic covalent chemistry.

Abstract: Dynamic covalent chemistry relates to chemical reactions carried out reversibly under conditions of equilibrium control. The reversible nature of the reactions introduces the prospects of "error checking" and "proof-reading" into synthetic processes where dynamic covalent chemistry operates. Since the formation of products occurs under thermodynamic control, product distributions depend only on the relative stabilities of the final products. In kinetically controlled reactions, however, it is the free energy differences between the transition states leading to the products that determines their relative proportions. Supramolecular chemistry has had a huge impact on synthesis at two levels: one is noncovalent synthesis, or strict self-assembly, and the other is supramolecular assistance to molecular synthesis, also referred to as self-assembly followed by covalent modification. Noncovalent synthesis has given us access to finite supermolecules and infinite supramolecular arrays. Supramolecular assistance to covalent synthesis has been exploited in the construction of more-complex systems, such as interlocked molecular compounds (for example, catenanes and rotaxanes) as well as container molecules (molecular capsules). The appealing prospect of also synthesizing these types of compounds with complex molecular architectures using reversible covalent bond forming chemistry has led to the development of dynamic covalent chemistry. Historically, dynamic covalent chemistry has played a central role in the development of conformational analysis by opening up the possibility to be able to equilibrate configurational isomers, sometimes with base (for example, esters) and sometimes with acid (for example, acetals). These stereochemical "balancing acts" revealed another major advantage that dynamic covalent chemistry offers the chemist, which is not so easily accessible in the kinetically controlled regime: the ability to re-adjust the product distribution of a reaction, even once the initial products have been formed, by changing the reaction's environment (for example, concentration, temperature, presence or absence of a template). This highly transparent, yet tremendously subtle, characteristic of dynamic covalent chemistry has led to key discoveries in polymer chemistry. In this review, some recent examples where dynamic covalent chemistry has been demonstrated are shown to emphasise the basic concepts of this area of science.