坂本 昌巳

<jats:title>Abstract</jats:title><jats:p>Solubility enhancement is a key issue for developing the perylene diimide‐based functional materials. Introduction of curved structure proved an effective solubilizing method without employing steric repulsion. In this work, wavily curved perylene diimides were developed as a new family of highly soluble curved perylene diimides. Moreover, their conformational dynamics, aggregating properties, electronic properties, and photovoltaic performances were thoroughly examined in comparison to the previously reported isomer exhibiting an arched curvature. The waved isomer demonstrated heightened rigidity and a greater propensity for aggregation compared to the arched isomer, likely attributed to its more planar structure. Each benzoxepin unit played a role in cancelling out the curvature on the opposite side. While the difference in the molecular curvature did not cause significant alterations in the photophysical and electron‐accepting properties, we identified that the modulation of the curved structure is effective in controlling the morphology of the photoelectric conversion layer.</jats:p>

1,2,4-Triazole and 1,2,4-triazoline are important components of bioactive molecules and catalysts employed in organic synthesis. Therefore, the efficient synthesis of these components has received significant research attention. However, studies on their structural diversity remain lacking. Previously, we developed chiral phase-transfer-catalyzed asymmetric reactions of α-imino carbonyl compounds with α,β-unsaturated carbonyl compounds and haloalkanes. In this study, we demonstrate the formal [3 + 2] cycloaddition reaction of α-imino esters with azo compounds under Brønsted base catalysis, resulting in the corresponding 1,2,4-triazolines in high yields. The results revealed that a wide range of substrates and reactants can be applied, irrespective of their steric and electronic characteristics. The present reaction made the general preparation of 3-aryl pentasubstituted 1,2,4-triazolines possible for the first time. Furthermore, a mechanistic study suggested that the reaction proceeds without isomerization into the aldimine form.

We synthesized N-alkyl-N-cinnamoyl amide type phosphine-olefin compounds 1 and found axial chirality in a C(aryl)-N(amide) bond in compounds 1 by HPLC analysis using a chiral stationary phase column. We successfully obtained enantiomeric isomers of 1 and demonstrated the use of (-)-1 for chiral ligands in Pd-catalyzed asymmetric allylic substitution reactions of allylic esters with indoles (up to 97% ee).

We synthesized cinnamoyl amide type compounds 1 with axial chirality. We demonstrated the use of (–)-1 for chiral ligands in Pd-catalyzed asymmetric allylic substitution reactions of allylic esters with indoles (up to 97% ee).

There has been a great focus on halogen-bonding as a unique interaction between electron-deficient halogen atoms with Lewis basic moieties. Although the application of halogen-bonded atoms in organic chemistry has been eagerly researched in these decades, the development of chiral molecules with halogen-bonding functionalities and their utilization in asymmetric catalysis are still in the\ir infancy. We have previously developed chiral halonium salts with amide functionalities, which behaved as excellent catalysts albeit in only two reactions due to the lack of substrate activation abilities. In this manuscript, we have developed chiral halonium salts with an N-nitrosamine moiety and applied them to the Mannich reaction of isatin-derived ketimines with malonic esters. The study focused on our novel bromonium salt catalyst which provided the corresponding products in high yields with up to 80% ee. DFT calculations of the chiral catalyst structure suggested that the high asymmetric induction abilities of this catalyst are due to the Lewis basic role of the N-nitrosamine part. To the best of our knowledge, this is the first catalytic application of N-nitrosamines.

Acetyl-substituted 7,12-dihydrobenzo[de]indolo[3,2-b]quinoline was developed as a N-substituted polycyclic heteroaromatic molecule via Pd-catalyzed cyclo-isomerization of an alkyne precursor, followed by intramolecular Goldberg amination. This compound showed unique reactivity, notably, base-mediated deacylative oxygenation and photo-Fries rearrangement. A series of products exhibited characteristic electronic properties based on the redox state of the corresponding nitrogen atoms. The photo-rearranged product, which possesses a 1,2-diaminoethene substructure, akin to the redox functionality of the natural flavin adenine dinucleotide, underwent reversible interconversion with the corresponding oxidized form. The efficient stabilization of the highly electron-rich 7,12-dihydrobenzo[de]indolo[3,2-b]quinoline skeleton was ascribed to the electron-withdrawing effect, intramolecular hydrogen bonding of the acetyl group, and local aromatic stabilization in the indole moiety.

The asymmetric amplification of p-anisoin was studied by attrition-enhanced deracemization in the presence of chiral standard amino acids. In this reaction, p-anisoin crystallized as a conglomerate, and deracemization under basic conditions was efficiently performed in 99% ee by Viedma ripening. Although the handedness of the enantioselective crystallization cannot be controlled by spontaneous crystallization, it could be governed by the coexistence of a catalytic amount of 16 chiral amino acids except cysteine, serine, and threonine. l-Amino acids tilted the handedness of enantiomer crystals to (R)-anisoin, while d-amino acids tilted it toward (S)-isomer crystals. It was clarified that this is due to the asymmetric transformation of p-anisoin in the mother liquor by the enantiomeric amino acids. The same slight asymmetric transformation in the solution phase was observed in α-hydroxyketones such as acetoin. Though the Soai reaction for an autocatalytic and asymmetric amplification system in the presence of a variety of chiral sources is famous, the crystallization-induced dynamic deracemization of p-anisoin provides the first chirality control system to be tilted by the enantioselective crystallization derived from many chiral additives.

We developed a chiral symmetry breaking method for monoacylated meso diols. The X-ray crystal structure analysis of monoacylated 1,4-anhydroerythritols, meso cyclic diols with a cis configuration, revealed that the O-(p-anisoyl) derivative crystallized as a racemic conglomerate of the P212121 crystal system. It was confirmed that the substrate racemized by intramolecular transfer of the acyl group in the presence of a catalytic amount of base. Evaporating the solvent gradually from the solution or Viedma ripening to promote crystallization-induced deracemization efficiently led to enantiomer crystals. These results provide the first successful example of asymmetric expression and amplification by deracemization of sugar derivatives without an external chemical chiral source. Furthermore, we applied this methodology to acyclic meso-1,2-diols. Three O-monoacylated substrates were successfully deracemized to 99 % ee by Viedma ripening. We also developed asymmetric desymmetrization of meso-1,2-diols by combining acylation and crystallization-induced deracemization.

We developed a chiral symmetry breaking method for monoacylated meso diols. The X-ray crystal structure analysis of monoacylated 1,4-anhydroerythritols, meso cyclic diols with a cis configuration, revealed that the O-(p-anisoyl) derivative crystallized as a racemic conglomerate of the P2(1)2(1)2(1) crystal system. It was confirmed that the substrate racemized by intramolecular transfer of the acyl group in the presence of a catalytic amount of base. Evaporating the solvent gradually from the solution or Viedma ripening to promote crystallization-induced deracemization efficiently led to enantiomer crystals. These results provide the first successful example of asymmetric expression and amplification by deracemization of sugar derivatives without an external chemical chiral source. Furthermore, we applied this methodology to acyclic meso-1,2-diols. Three O-monoacylated substrates were successfully deracemized to 99 % ee by Viedma ripening. We also developed asymmetric desymmetrization of meso-1,2-diols by combining acylation and crystallization-induced deracemization.

Atroposelective resolution for axially chiral nicotinamides was achieved by dynamic chiral salt formation with L-DBTA using six types of nicotinamides that could not be optically resolved by the preferential crystallization method. Kinetic studies of their racemization indicated that the chiral conformation was retained for a significant period of time. Two methods of crystallization-induced asymmetric transformation were examined by dynamic diastereomeric salt formation: solvent evaporation from a supersaturated solution, and attrition-enhanced asymmetric transformation. The attrition method was more effective for asymmetric amplification of diastereomeric salts of axially chiral materials. Attrition of equimolar amount of the nicotinamide salts with L-DBTA converged to one diastereomer salts, and the corresponding enantiomers in 87-99 % ee were obtained after the chiral acid was removed. Changing the ratio of two of the nicotinamides with L-DBTA to 1 : 2 inverted the axial chirality.

Atroposelective resolution for axially chiral nicotinamides was achieved by dynamic chiral salt formation with L-DBTA using six types of nicotinamides that could not be optically resolved by the preferential crystallization method. Kinetic studies of their racemization indicated that the chiral conformation was retained for a significant period of time. Two methods of crystallization-induced asymmetric transformation were examined by dynamic diastereomeric salt formation: solvent evaporation from a supersaturated solution, and attrition-enhanced asymmetric transformation. The attrition method was more effective for asymmetric amplification of diastereomeric salts of axially chiral materials. Attrition of equimolar amount of the nicotinamide salts with L-DBTA converged to one diastereomer salts, and the corresponding enantiomers in 87–99 % ee were obtained after the chiral acid was removed. Changing the ratio of two of the nicotinamides with L-DBTA to 1 : 2 inverted the axial chirality.

Asymmetric synthesis was performed by combining the photochemical reaction of an achiral substrate followed by crystallization-induced deracemization. The results indicated that a fused indoline produced by photochemical intramolecular δ-hydrogen abstraction and cyclization of N-(5-chloro-2-methylphenyl)phthalimide crystallized as a racemic conglomerate. Since this substrate has an aminal skeleton, racemization involving a ring-opening and ring-closing equilibrium process occurred under suitable conditions. Efficient racemization was observed in acetone containing a catalytic base, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). Crystallization-induced dynamic deracemization by Viedma ripening from racemic indoline was performed with an excellent enantioselectivity of 99 % ee. Furthermore, one-pot asymmetric synthesis of the indoline was achieved by the photochemical reaction of achiral phthalimide followed by continuous attrition-enhanced deracemization converging to 99 % ee of enantiomeric crystals. This is the first example of asymmetric expression and amplification by photochemical hydrogen abstraction and crystallization-induced dynamic deracemization.

Chiral symmetry breaking of 3-phenylsuccinimides by crystallization-induced dynamic deracemization was performed. We found that N-propyl and N-(3-methoxyphenyl)-3-phenylsuccinimides crystallized as racemic conglomerates, and their crystal structures were determined by single-crystal X-ray structure analysis. Their rapid racemization via enolate ions under basic conditions was confirmed. Crystallization of a small amount of racemic substrates from the solution by evaporating solvent with stirring promoted deracemization from 55% to 98% ee. On the other hand, attrition-enhanced deracemization (Viedma ripening) was applied to deracemization experiments on a larger scale converging to enantiomeric crystals with >99% ee.

Asymmetric synthesis was performed by combining the photochemical reaction of an achiral substrate followed by crystallization-induced deracemization. The results indicated that a fused indoline produced by photochemical intramolecular delta-hydrogen abstraction and cyclization of N-(5-chloro-2-methylphenyl)phthalimide crystallized as a racemic conglomerate. Since this substrate has an aminal skeleton, racemization involving a ring-opening and ring-closing equilibrium process occurred under suitable conditions. Efficient racemization was observed in acetone containing a catalytic base, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). Crystallization-induced dynamic deracemization by Viedma ripening from racemic indoline was performed with an excellent enantioselectivity of 99 % ee. Furthermore, one-pot asymmetric synthesis of the indoline was achieved by the photochemical reaction of achiral phthalimide followed by continuous attrition-enhanced deracemization converging to 99 % ee of enantiomeric crystals. This is the first example of asymmetric expression and amplification by photochemical hydrogen abstraction and crystallization-induced dynamic deracemization.

Chiral symmetry breaking of 3-phenylsuccinimides by crystallization-induced dynamic deracemization was performed. We found that N-propyl and N-(3-methoxyphenyl)-3-phenylsuccinimides crystallized as racemic conglomerates, and their crystal structures were determined by single-crystal X-ray structure analysis. Their rapid racemization via enolate ions under basic conditions was confirmed. Crystallization of a small amount of racemic substrates from the solution by evaporating solvent with stirring promoted deracemization from 55% to 98% ee. On the other hand, attrition-enhanced deracemization (Viedma ripening) was applied to deracemization experiments on a larger scale converging to enantiomeric crystals with >99% ee.

The study of chirogenesis of organic molecules is important to elucidate the origin of the homochirality of biomolecules on Earth. Here, we have accomplished chiral symmetry breaking from a racemate using optical vortices with orbital angular momentum and a helical wavefront. We propose a new methodology of asymmetric transformation by the combination of enantioselective crystal nucleation by irradiation with optical vortices and crystallization-induced dynamic optical resolution of conglomerate crystals. Chiral green vortices generated using a spiral phase plate (SPP) with a 532 nm CW-laser were used to irradiate a supersaturated solution of a racemic isoindolinone, leading to crystal nucleation. The handedness of the crystals were controlled by the winding direction of the chiral optical vortices. The molecular chirality of the isoindolinone was then amplified by dynamic crystallization.

The highly enantioselective synthesis of p-anisoin was achieved via the benzoin condensation of a prochiral p-anisaldehyde using achiral NHC catalysts such as vitamin B1. In this reaction, p-anisoin crystallized as a conglomerate, and the deracemization of racemic p-anisoin under basic conditions was efficiently performed by Viedma ripening. Although the handedness of the enantioselective crystallization could not be controlled by spontaneous crystallization, it could be controlled by the coexistence of a catalytic amount of optically active valine. It was clarified that this is due to the asymmetric transformation of p-anisoin with enantiomeric valine in the mother liquor.

<p>α-Tetrasubstituted-α-amino thioesters were synthesised through chiral phase-transfer catalysed Michael reaction of imino thioesters in up to 97% yield with up to 81% ee.</p>

<p>The first regioselective umpolung alkylation of α-iminoesters with alkyl halides mediated by iminophosphorane has developed (up to 82% yield).</p>

<p>Bromonium salts have been typically but infrequently used as good leaving groups owing to their high nucleofugality. Herein, we report the synthesis of stable bromonium salts and their first catalytic application, with excellent product yield.</p>

Efficient generation and amplification of chirality from prochiral substrates in the Diels–Alder reaction (DA reaction) followed by dynamic crystallization were achieved without using an external chiral source. Since the DA reaction of 2-methylfuran and various maleimides proceeds reversibly, an exo-adduct was obtained as the main product as the reaction proceeded. From single crystal X-ray structure analysis, it was found that five of ten exo-adducts gave conglomerates. When 2-methylfuran and various maleimides with a catalytic amount of TFA were reacted in a sealed tube, the exo-DA adducts were precipitated from the solution, while the reaction mixtures were continuously ground and stirred using glass beads. Deracemization occurred and chiral amplification was observed for four of the substrates. Each final enantiomeric purity was influenced by the crystal structure, and when enantiomers were included in the disorder, they reached an enantiomeric purity reflecting the ratio of the disorder. The final ee value of the 3,5-dimethylphenyl derivative after chiral amplification was 98% ee.

© 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Attrition-enhanced deracemization of two axially chiral nicotinamides, crystallizing as a conglomerate of a P21 crystal system, was performed. N,N-Dialkylnicotinamides with substituents on the 2- and 4-positions of the pyridine ring exhibited stable axial chirality due to rotationally restricted scaffolds for the Ar–C(=O)N bond. Crystallization of the racemic mixtures from the melt or attrition-enhanced deracemization led to the chiral breaking of symmetry to give 95–96 % ee of enantiomorphic crystals.