三宅 由寛

We prepared a free-base 10,20-diphenyl-5,15-diazaporphyrin and its Ni(II), Cu(II), Pd(II), and Pt(II) complexes. These molecules uniformly form an infinite one-dimensional [Formula: see text]-stacking array in the solid state. The four-fold intermolecular hydrogen bonding interactions between the meso-nitrogen atom of the diazaporphyrin core and the ortho-hydrogen atom of the phenyl substituent dominate the crystal packing arrangement. The present study revealed that the meso-nitrogen atom of diazaporphyrins would be used as an inherent hydrogen bonding acceptor to construct supramolecular assemblies.

Abstract We have succeeded in the synthesis of various tetrasilatetrathia[8]circulenes with alkyl and aryl groups on the silicon atoms. We also disclosed the effect of phosphine ligands on palladium-catalyzed silylation of tetraiodotetrathienylene and rhodium-catalyzed intramolecular silylation of tetrasilyltetrathienylenes. Experimental and theoretical analysis revealed the effect of the substituents on the silicon atoms on their electronic property.

<jats:p> Fluorination of sp<jats:sup>3</jats:sup> C–H bonds has attracted considerable attention as a promising method for the synthesis of organofluorine compounds. Manganese porphyrins have been extensively investigated as catalysts in the fluorination of saturated sp<jats:sup>3</jats:sup> C–H bonds. Recently, we have found that iron(III) 5,15-diazaporphyrins, which are porphyrin analogues with imine-type sp<jats:sup>2</jats:sup>-hybridized nitrogen atoms at the meso-positions, showed high catalytic performance in the oxidation of sp<jats:sup>3</jats:sup> C–H bonds. Here we disclose the synthesis, structure, and electronic properties of manganese(III) 5,15-diazaporphyrins. We also demonstrate the catalysis of chloromanganese(III) 5,15-diazaporphyrins for benzylic fluorination. </jats:p>

<p>Iron hexamesityl-5,15-diazaporphyrin was successfully synthesized. Its use for catalytic oxidation of cyclooctane showed high performance with a total TON up to 731. The introduction of bulky mesityl groups prevented the catalyst deactivation via formation of a μ-oxo dimer.</p>

5,15-Diazaporphyrins are porphyrin analogues with imine-type sp2-hybridized nitrogen atoms at the meso-positions. Even though these compounds are more electron-deficient than regular porphyrins, the use of iron diazaporphyrins as catalysts has not been reported. Herein, we disclose the synthesis, structure, and electronic properties of iron(III) 5,15-diazaporphyrins. We evaluate their structures and electronic natures by X-ray analysis and electrochemical analyses. We also demonstrate that chloroiron(III) 5,15-diazaporphyrins exhibit high catalytic activity in the direct oxidation of alkanes due to their intrinsic electron-deficient nature. On the basis of stoichiometric reactions of iron(III) diazaporphyrin with iodosylbenzene as an oxidant, it was possible to demonstrate the existence of an iodosylbenzene-iron diazaporphyrin adduct reaction intermediate that serves as a reservoir to generate oxo-iron species.

© 2020 The Chemical Society of Japan. We have developed the synthesis of 1,3,6,8-tetramethoxy-2,7-diazapyrene through reductive aromatization of naphthalene diimide. The methoxy groups were readily converted to a variety of alkyl groups through Ni-catalyzed cross-coupling reaction with alkyl Grignard reagents. The peripheral substituents significantly influenced the packing structures of 2,7-diazapyrenes in the solid state.

<p>Synthetic route for hetero[8]circulenes are classified into the annulative construction of eight-membered ring and the peripheral ring fusion of eight-membered ring. Post-transformation enables the tuning of structural features and electronic nature.</p>

Single electron oxidation of amines provides an efficient way to access synthetically useful a-aminoalkyl radicals as reactive intermediates. After the single electron oxidation of amines, fragmentation of the resulting radical cations proceeds to give the alpha-aminoalkyl radicals along with generation of a proton. In the synthetic utilization of the a-aminoalkyl radicals, precise control of single electron transfer is essential, because further oxidation of the alpha-aminoalkyl radicals occurs more easily than the starting amines and the a-aminoalkyl radicals are converted into the corresponding iminium ions. As a result, photoinduced single electron transfer is quite attractive in the synthetic utilization of the alpha-aminoalkyl radicals. Recently, visible light-photoredox catalysis using transition metal-polypyridyl complexes and other dyes as catalysts has attracted considerable attention, where useful molecular transformations can be achieved through the single electron transfer process between the excited catalysts and substrates. In this context, MacMillan et al. (Science2011, 334, 1114, DOI: 10.1126/science.1213920) reported an aromatic substitution reaction of cyanoarenes with amines, where a-aminoalkyl radicals work as key reactive intermediates. Pandey and Reiser et al. ( Org. Lett. 2012, 14, 672, DOI: 10.1021/ol202857t) and our group (Nishibayashi et al. J. Am. Chem. Soc. 2012, 134, 3338, DOI: 10.1021/ja211770y) independently reported reactions of amines with alpha,beta-unsaturated carbonyl compounds, where addition of a-aminoalkyl radicals to alkenes is a key step. After these earliest examples, nowadays, a variety of transformations using the a-aminoalkyl radicals as reactive intermediates have been reported by many groups. The alpha-aminoalkyl radicals are usually produced from amines by single electron oxidation and the subsequent deprotonation of the C-H bond adjacent to the nitrogen atom. In addition, the alpha-aminoalkyl radicals are also produced from a-silylamines and a-amino acids in high efficiency through desilylation or decarboxylation after the single electron oxidation. The generated alpha-aminoalkyl radicals are utilized in a variety of reaction systems. In fact, reactions based on the addition of a-aminoalkyl radicals to alkenes and other unsaturated bonds have been extensively studied. Aromatic and other types of substitution reactions have also been investigated. Some of these transformations are achieved by combination of photoredox catalysts and other catalysts such as Bronsted and Lewis acids, organocatalysts, and transition metal catalysts. It is also noteworthy that the enantioselective reactions have been accomplished by combination of photoredox catalysts and chiral catalysts. The strategy for the generation of alpha-aminoalkyl radicals can be applied to utilize other types of alkyl radicals. In the generation of alpha-aminoalkyl radicals, the bond dissociation of the radical cations occurs at the a-position of amines. In relation to this process, synthetic utilization of other types of alkyl radicals generated by the bond dissociation of the radical cations at a remote position has been also investigated. These alkyl radicals have been applied to molecular transformations in a manner similar to the alpha-aminoalkyl radicals. Recently, organic synthesis using the alpha-aminoalkyl radicals and related alkyl radicals has been studied extensively. In this Account, we describe recent advances in photoredox-catalyzed synthetic utilization of these alkyl radicals.

Recently, we have developed visible-light-mediated functionalization of nitrogen-containing organic compounds. These reactions include photoinduced electron transfer as a key step, where the fragmentation of aminium radicals generated from one electron oxidation of amines provides the coresponding alpha-aminoalkyl radicals and aminobenzyl radicals and they work as reactive intermediates. This methodology provides a new approach for the synthesis of nitrogen-containing organic compounds.

We have designed and prepared a series of novel PNP pincer ligands based on N-methyl-4,4'-bipyridinium for the construction of stable complexes toward two steps of single electron transfer reactions, where p-quinoid-type complexes play a key role. Electrochemical studies reveal that two reduction waves of these complexes are similar to those of methylviologen and the corresponding p-quinoid type complexes form as stable two electron reduced species. The rhodium complex bearing PNP pincer ligand based on N-methyl-4,4'-bipyridinium is also found to work as a catalyst for dihydrogen production under the photoinduced electron-transfer conditions.

Reactions of primary and secondary benzylic chlorides with trifluoromethyltrimethylsilane in the presence of a catalytic amount of copper(I) thiophene-2-carboxylate (CuTC) have been found to give the corresponding benzylic trifluoromethylated products in good to high yields.

We have succeeded in the visible light-mediated synthetic use of alpha-aminoalkyl radicals derived from alpha-silyl secondary amines toward addition to alpha,beta-unsaturated carbonyl compounds. The resulting gamma-aminocarbonyl compounds are converted into gamma-lactams and pyrroles in a one-pot process.

Reactions of primary and secondary benzylic chlorides with trifluoromethyltrimethylsilane in the presence of a catalytic amount of copper(I) thiophene-2-carboxylate (CuTC) have been found to give the corresponding benzylic trifluoromethylated products in good to high yields.

Reactions of propargylic halides with trifluoromethyltrimethylsilane in the presence of a catalytic amount of copper(i) thiophene-2-carboxylate (CuTC) have been found to give the corresponding trifluoromethylated products in good to high yields with a high selectivity. © 2013 The Royal Society of Chemistry.