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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Nature Communications  

Primary amines are highly ubiquitous functional groups found in diverse natural products and building blocks. Despite their widespread application as nucleophiles, the potential for facile deaminative functionalization utilizing primary amines, particularly sterically hindered α-tertiary amines, has remained less explored. Herein, we report catalytic direct synthesis of aliphatic diazenes from sterically hindered α-tertiary amines. The catalytic diazene synthetic method exhibits wide functional group tolerance, allowing for expeditious access to a wide array of hitherto-inaccessible, highly congested diazenes in a short time. Noteworthy is that the present catalytic method enables the synthesis of various hetero-diazenes using distinct α-tertiary amines in just one step for the first time. The catalytic process could also be readily incorporated into Fmoc solid-phase peptide synthesis, enabling the synthesis of elastin-derived diazene, which contains 12 amino acid residues. The catalytic diazene synthetic method enables efficient deaminative transformation of C–N bonds into C–halogen, C–H, C–O, C–S, C–Se, and C–C bonds through carbon-centered radical formation.

DOI： 10.1038/s41467-025-61662-9

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Organic Letters  

Reductive radical generation has become a cornerstone of modern photoredox chemistry. However, the synthesis of functionalized radical precursors remains a tedious multistep process. In this study, we focus on the potential of the nitro group as a redox-active functional group and present denitrative alkenylation of nitroalkanes, facilitated by photoreductive generation of alkyl radicals from nitroalkanes. By taking advantage of the facile α-functionalization of nitroalkanes, we successfully generate various functionalized alkyl radicals, which are subsequently used in the alkenylation reactions.

DOI： 10.1021/acs.orglett.4c03526

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Organic Letters  

We present the reductive homologation of nitroalkanes through the utilization of the denitrative aminoalkylation reaction. This transformation is accomplished by the radical-radical coupling of alkyl radicals derived from nitroalkanes and persistent aminoalkyl radicals. By capitalizing on the diverse α-functionalization of nitroalkanes, α,β-multifunctionalized amines can be readily accessed.

DOI： 10.1021/acs.orglett.4c03269

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Asian Journal of Organic Chemistry  

Functionalized 3-azabicyclo[3.1.0]hexanes are highly interesting for their physiochemical and pharmacological properties. We report an unprecedented direct bridge-head C(sp³)−H borylation by cooperative iridium/aluminum catalysis. This reaction proceeds under mild conditions in good yields with moderate to complete site selectivities. Moreover, the use of a BINOL-based chiral aluminum catalyst renders the synthesis of enantioenriched alkylboronate products. We also disclose its synthetic utility through rapid diversifications without any loss of the stereochemical information.

DOI： 10.1002/ajoc.202300487

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Synlett  

A new protocol for the catalytic denitrative generation of radicals from nitroalkanes was disclosed. 9-Fluorenol acts as a singleelectron transfer catalyst that reduces nitroalkanes to promote the C-NO<inf>2</inf>bond cleavage, followed by the formation of alkyl radicals. The obtained radicals participate in diverse transformations such as hydrogenation, Giese addition, spirocyclization, and Minisci reactions by using appropriate trapping reagents. The present system outperforms conventional methods using tin hydrides in terms of cost, toxicity, and experimental operations.

DOI： 10.1055/a-1942-0683

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Total pages：x, 212p   Language：Japanese  

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Language：Japanese  

DOI： 10.24496/tennenyuki.63.0_343-348

CiNii Research

Language：Japanese   Presentation type：Oral presentation (general)  

Language：Japanese  

Crops grown on alkaline soils, which cover about one-third of the world lands, are prone to iron-deficiency stress because of the low solubility of iron there. To acquire the insoluble iron efficiently, graminaceous plants have developed a unique strategy characterized by the synthesis and secretion of an iron-chelator phytosiderophore and a specific uptake system of iron(III) in its complex. Mugineic acid (MA) 1 was first identified as phytosiderophore in barley and its analogues have then been isolated and identified from various graminaceous species and cultivars; they all form water-soluble 1:1 complexes with iron(III). Owing to its significant implication in plant physiology, this iron up-take system has been a subject of intensive research since its discovery 30 years ago. However, a limited supply of phytosiderophores has been a severe bottleneck particularly for the study on the transport mechanism. Therefore, it is essential to establish an ample supply source of MA 1 and/or 2'-deoxymugineic acid (DMA) 2. In addition, supply of DMA will be potentially important to solve the worldwide problem of shortage of food supply because their use may make cultivation possible even on alkaline soils which are not favorable for farming. In this presentation, 1) the investigation of potential values of DMA as a fertilizer and synthetic studies toward an ample supply of DMA, 2) the mugineic acid derivatives as molecular probes for the mechanistic elucidation, and 3) development of 1,3a,6a-triazapentalenes as a breakthrough fluorescent molecule will be discussed. 1) A practical synthesis of L-azetidine-2-carboxylic acid, an expensive starting material for DMA, was established by using asymmetric organocatalyst. The normal rice plant was able to grow even in alkaline hydroponic culture by the addition of DMA and iron(III) salt. 2) A hydroxy group in mugineic acid (MA) that was not needed for Fe(III) complexation was used for the introduction of various labeling groups through propargylation and a click reaction. Labeled MA was incorporated as a phytosiderophore into Xenopus oocytes through the HvYS1 transporter, as determined by an electrophysiological assay and fluorescence microscopy. 3) An efficient and versatile method was established for the preparation of 1,3a,6a-triazapentalenes. The 1,3a,6a-triazapentalene skeleton without an additional fused ring system was discovered to be a compact and highly fluorescent chromophore, which exhibited various interesting fluorescent properties such as a noteworthy correlation of luminescent wavelength with the Hammett σ_p value and a strongly positive solvatofluorochromism.

DOI： 10.24496/tennenyuki.54.0_223

CiNii Research

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Language：Japanese  

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Language：Japanese   Presentation type：Public lecture, seminar, tutorial, course, or other speech  

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Authorship：Lead author,　Last author,　Corresponding author   Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

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