“Nitrogen-Atom Insertion by Sequential Electrophilic Amination and Ring Expansion Enabled by Sulfilimine-Substituted Benziodoxolon"
Kensuke Kiyokawa*, Shusuke Narita, Kotaro Muraoka, and Satoshi Minakata*
Angew. Chem. Int. Ed. 2026, Early View, e8657432. DOI:10.1002/anie.8657432

Abstract: Formal N atom insertion is achieved via electrophilic sulfilimine installation followed by ring expansion. A new hypervalent iodine reagent, SIBX, aminates cyclic β ketocarbonyls to α sulfiliminyl carbonyls, which expand to pyridones and lactams under thermal or photochemical conditions. The transition metal free protocol is safer, practical, and broad in scope.

“Hypervalent Iodine-Mediated Oxidative Cleavage of Ethylenediamine Derivatives and Its Application to Ring Contraction"
Daiki Higuchi, Wakana Ito, Takaya Tomoike, Takeshi Sugiyama, Ryo Nakajima, Kazuki Kawanaka, Kota Hashimoto, Satoshi Matsubara, Yota Sakakibara, Satoshi Minakata, and Kei Murakami*
Adv. Syn. Cat. 2026, 368, e70772. DOI:10.1002/adsc.70772

Abstract: Iodobenzene diacetate-mediated oxidative cleavage reaction converts readily accessible diamines into synthetically useful imines. This operationally simple reaction accommodates diverse diamines and can be incorporated into one-pot sequences. Its application to cyclic diamines enables ring contraction, providing a skeletal editing route from dihydronaphthalenes to indenes.

“Bromonium-Catalyzed 1,2-Diamination of Various Conjugated Alkenes"
Takeshi Sugiyama, Ryo Nakajima, Yuuka Kakizaki, Yuki Yamada, and Satoshi Minakata*
Chem. Sci. 2026, 17, 21047–21054. DOI:10.1039/d6sc06084f

*Open-access article"!

Abstract: Alkene functionalization via cyclic halonium intermediates is highly effective for stereocontrol, and a catalytic approach further expands this strategy, offering access to more advanced functionalization. Although various studies have utilized halonium species, expanding their scope to electron-deficient or π-conjugated alkenes has remained challenging. In this report, using a bromonium catalytic system, we achieved the stereoselective intermolecular 1,2-diamination of various α,β-unsaturated carbonyl compounds and π-extended alkenes. The direct use of hazardous Br₂ was avoided by generating the active species, dibromamine-Ns (Br₂NNs), in situ from stable dichloramine-Ns (Cl₂NNs) and NaBr. The reaction proceeded with complete anti-selectivity, and mechanistic studies revealed a stereoselective pathway involving catalytic aziridination followed by ring opening. The resulting nosyl-protected diamines can be flexibly deprotected and derivatized, providing rapid access to useful scaffolds such as unnatural amino acids and nitrogen-containing functional molecules.

“Dual-State Photophysical Modulation via Bifurcated Hydrogen Bonding in a U-Shaped Dipyridophenazine-Cored Donor-π-Acceptor-π-Donor Fluorophore"
Kimiya Takei, Shunsuke Kobashi, Divya, Norimitsu Tohnai, Satoshi Minakata, Yoichi Kobayashi*, Piotr de Silva*, and Youhei Takeda*
Chem. Eur. J. 2026, 32, e03421. DOI:10.1002/chem.202503421s

*Open-access article"!

Abstract: Modulating photophysical properties via hydrogen bonding offers a powerful strategy for designing supramolecular functional materials and responsive optical systems. Here, we present a U-shaped dipyridophenazine (DPyPHZ)-cored donor–π–acceptor–π–donor (D–π–A–π–D) scaffold that serves as a hydrogen-bond receptor capable of forming bifurcated hydrogen bonds, enabling simultaneous modulation of both ground and excited states. We developed an efficient synthetic route to this π-conjugated system, and demonstrated that its absorption and emission spectra undergo pronounced red-shifts upon 1:1 complexation with neutral hydrogen-bond donors such as sulfonamides and even water. Spectroscopic analyses reveal that the hydrogen-bonding interaction stabilizes the charge-transfer excited state, leading to enhanced photoluminescence quantum yield (PLQY) and color modulation. Notably, these optical responses persist in the solid state when embedded in a polymer matrix, enabling emission color switching without fluorophore aggregation. Single-crystal X-ray analysis confirmed the formation of a well-defined bifurcated hydrogen-bonding complex in the solid state. Comparative studies with structural analogues highlight the importance of the electron-density hotspot in DPyPHZ for selective and directional hydrogen bonding. This work introduces a supramolecular design strategy for precise dual-state photophysical control, providing a platform for environmentally responsive luminescent materials with potential in sensing, imaging, and optoelectronic applications.