Kosuke Katagiri

A novel P-chirogenic phosphine ligand, (S,S)-1,2-bis-[(ferrocenyl)methylphosphino]ethane: synthesis and use in rhodium-catalyzed asymmetric hydrogenation and palladium-catalyzed asymmetric allylic alkylation

Abstract A new P-chirogenic diphosphine ligand, ( S , S )-1,2-bis[(ferrocenyl)methylphosphino]ethane, was prepared via phosphine–borane intermediates. The ligand was used in the rhodium-catalyzed asymmetric hydrogenation of dehydroamino acid derivatives (up to 77% enantioselectivity) and in the palladium-catalyzed asymmetric allylic alkylation of 1,3-diphenyl-2-propenyl acetate (up to 95% enantioselectivity).

Hydrogen-bonded networks formed from tri- and tetra-substituted adamantanes bearing dimethoxyphenol moieties and their 1,3,5-trinitrobenzene complexes via charge-transfer interactions

Adamantane derivatives represent valuable scaffolds for the generation of interesting supramolecular architectures in the crystalline state because of their high symmetry and the facile attachment of functional groups. Tri- and tetrasubstituted adamantanes with dimethoxyphenol moieties were designed and prepared as novel hydrogen-bonded (H-bonded) electron-donor molecules with the aim of introducing donor–acceptor interactions into the H-bonded structures. Single-crystal X-ray analysis of ternary molecules based on adamantane (1) revealed the creation of one-dimensional (1D) ladders through H-bonding between methoxy and hydroxyl groups of dimethoxyphenol units. Individual ladders assembled into three-dimensional (3D) networks via multiple C–H⋯O interactions. In the crystals of tetrasubstituted adamantane (2), H-bonded 1D polymers composed of a cyclic framework were produced, which were aligned into a 3D network structure through C–H⋯O interactions. In the 1,3,5-trinitrobenzene (3) charge-transfer complex of trisubstituted adamantane, infinite H-bonded two-dimensional (2D) sheets were sustained by the formation of multiple H-bonds. The 2D sheets were observed to stack with guest molecules via charge-transfer interactions. The complexation of 3 with 2 led to the formation of H-bonded 2D sheets possessing two types of cavities, which were intermolecularly interdigitated via donor–acceptor interactions, resulting in the construction of a 3D network structure.

Helicity Induction in Three π‐Conjugated Chromophores by Planar Chirality of Calixamide

Shall we twist? Three-dimensional arrangement of π-conjugated chromophores with triple-stranded helicity was achieved by using the planar chirality of m-calix[3]amide. Based on spectroscopic data and theoretical calculations, the dynamic and preferred helical characters of bithiophene units embedded in the tubular molecule were elucidated, and the absolute configuration was determined.

Trifluoroacetylation-Induced Houben−Hoesch-Type Cyclization of Cyanoacetanilides: Increased Nucleophilicity of CN Groups

Trifluoroacetic anhydride-mediated tandem trifluoroacetylation/cyclization of cyanoacetanilides proceeded efficiently under mild conditions to give 4-hydroxy-3-trifluoroacetylquinolin-2(1H)-ones in good yields. Isolation and direct observation of the reaction intermediates revealed that alpha-trifluoroacetylation resulted in the shortening of C[triple bond]N bonds and that the electron density of CN groups was high. A plausible reaction mechanism based on the results is also described.

Chiral Spherical Molecule Constructed from Aromatic Amides : Facile Synthesis and Highly Ordered Network Structure in the Crystal

A novel chiral spherical molecule composed of aromatic amide was synthesized in short steps. The molecule is constructed from four benzene rings connected by six amide bonds and has multiple functionalizable points and an asymmetric structure. The racemic spherical molecule constructed channel network structures in the crystalline state.

2-D coordination network of a cyclic amide with a lanthanide metal cation and its columnar stacking

Novel complexes of a cyclic amide with lanthanide metal cations form 2-D coordination networks; different metal cations give different chiral properties in the crystal structure.

Adamantane-Based Oxacyclophanes Containing Pyrazines: Synthesis, Crystal Structure, and Self-Assembly Behavior

Two adamantane-based oxacyclophanes were synthesized by the SNAr reaction of bis-phenol derivatives based on adamantane with 2,6-dichloropyrazine. Their crystal structures had distorted or twisted 1,3-alternate conformations. The oxacyclophanes indicated no formation of spherical aggregates in acetone. However, addition of water into the solution caused the generation of hollow spherical aggregates with a multilayer membrane. Over time, the hollow spheres were induced into fibrous and network assemblies, which were eventually transformed into single crystals.

Preparation of Magnetic Ionic Liquids Composed of Hybrid-Type Anions

1-Ethyl-3-methylimidazolium ethylsulfate ([C2mim][EtSO4]) was mixed with iron(III) chloride·6H2O to give a magnetic ionic liquid composed of the hybrid-type anion, [C2mim][FeCl3·EtSO4], which showed a slightly different magnetic property than [C2mim][FeCl4]. On the other hand, reaction of [C2mim][EtSO4] with cobalt(II) chloride hydrate formed [C2mim]2[CoIICl4], the structure of which was characterised by X-ray crystallographic analysis.

Polymorphism or pseudopolymorphism of a macrocyclic compound: helical structure, layered structure and pseudorotaxane constructed by weak intermolecular interactions

Molecules of macrocyclic aromatic hydrocarbon 1 assembled to form various three-dimensional (3D) structures via weak intermolecular interactions, including aromatic–aromatic interactions (1a–d). In the crystal obtained from a chloroform and acetonitrile mixture (1a), the molecules arranged in a columnar stack with a progressive helical twist between adjacent molecules due to intermolecular aromatic–aromatic interactions. The chirality of the helices was spontaneously resolved within individual single crystals. In the crystal obtained from a chloroform and nonane mixture (1b), the molecules formed a columnar stack through tilted T-shaped aromatic–aromatic interactions. Furthermore, in the crystal obtained by vapour diffusion of n-hexane or ethyl acetate into a chloroform solution, inclusion compounds (1c and 1d) were formed via van der Waals interactions between the guest molecule and the benzene ring of the biphenyl unit. The n-hexane penetrated 1 to construct [3]pseudorotaxane and an ethyl acetate molecule was trapped by 1.

Acid-mediated ring-expansion reaction of N-aryl-2-vinylazetidines: synthesis and unanticipated reactivity of tetrahydrobenzazocines.

The aza-Clasen rearrangement of N-aryl-2-vinylazetidines has been explored. N-Aryl-2-vinylazetidines were transformed to corresponding tetrahydrobenzazocines in good yields. Unexpectedly, the tetrahydrobenzazocine was unstable and readily isomerized to vinyltetrahydroquinoline in the presence of acid. The mechanism of this ring contraction was studied in detail.