The University of Osaka · Chemistry
Professor Haruyasu Asahara's research lab specializes in organic synthesis and physical organic chemistry, with a focus on developing novel catalytic and radical-based methods for C–H bond functionalization, particularly oxygenation and alkylation reactions. The lab explores metal-free and metal-catalyzed transformations to construct complex molecular architectures, including α-hydroxy-β-dicarbonyl compounds and tricyclic frameworks, with applications in pharmaceuticals and fine chemicals. A key theme is the use of radical intermediates—such as chlorine radicals and ClO₂•—to achieve selective and mild functionalization of sp³ C–H bonds and polymer surfaces. The lab also investigates structure-reactivity relationships through kinetic studies to guide the design of new electrophilic reagents and synthetic tools.
Figures are computed from collected data and may differ slightly.
A new method for synthesizing polyalkylated/arylated nicotinates is established using a condensation of enamino esters with enones in the presence of FeCl<sub>3</sub>. This method facilitates the introduction of alkyl or aryl groups at any position on demand, which has not been achieved by other procedures.
Metal–plastics adhesion has received much attention from researchers due to its potential use in various industrial applications. However, the adhesion of plastics with metals is poor due to the low surface energy of plastics. Accordingly, the adhesion of plastics usually requires surface modification or the use of an adhesive primer. Recently, we developed a polymer surface modification method using the light-activated chlorine dioxide (ClO2•) radical as oxidant. In this study, we investigated
The oxygenation of C(sp<sup>3</sup>)-H bonds is a key chemical reaction in the production of fine chemicals and pharmaceuticals. Hydrogen atom transfer has recently gained significant attention for its ability to functionalise C-H bonds. The C-H bond can be activated by transferring the H radical to a hydrogen acceptor such as the chlorine radical (Cl˙). Thus, the Cl˙ generated by light irradiation can be used to initiate C-H oxygenation reactions, in which molecular oxygen is used as the oxidan
A direct metal-free α-hydroxylation of α-unsubstituted β-oxoesters and β-oxoamides was developed using m-chloroperbenzoic acid as the oxidant. This transformation enabled straightforward metal-free access to important α-hydroxy-β-dicarbonyl moieties under mild reaction conditions. Furthermore, the hydroxylated products were readily converted into vicinal tricarbonyl compounds, which are useful synthetic precursors of numerous biological targets.
Kinetics of the reactions of bissulfonyl ethylenes with various carbanions, a sulfur ylide, and siloxyalkenes have been investigated photometrically at 20 °C. The second-order rate constants have been combined with the known nucleophile- specific parameters N and s(N) for the nucleophiles to calculate the empirical electrophilicity parameters E of bissulfonyl ethylenes according to the linear free energy relationship log k(20 °C)=s(N)(N+E). Structure-reactivity relationships are discussed, and i
The BF3-catalyzed reactions of diphenyl-substituted and endo-monophenyl-substituted homobenzoquinone epoxides proceeded through a regioselective oxirane ring opening followed by participation of a pi-aryl transannular cyclization to give the tricyclic diketo alcohols. The conformationally semirigid ethano-bridged diphenyl-substituted homologues also provided similar diketo alcohols and the subsequent ring-expanded cycloheptenedione (via a subsequent 1,2-acyl migration associated with cyclopropan
In the work being reported here, β-nitrostyrenes bearing an ethoxycarbonyl group at the β-position serve as scaffolds for the synthesis of α,β-difunctionalized alkenes. Nitrocinnamates undergo Michael addition reactions with versatile sp<sup>3</sup>- and sp<sup>2</sup>-nucleophiles such as alcohols, Grignard reagents, alkylcopper, and dialkylzinc to afford β-substituted nitroethane derivatives. However, various attempts to obtain a double bond via nitrous acid elimination failed because steric r
We report the visible-light-induced <i>in situ</i> preparation of COCl<sub>2</sub> through the oxygenation of chloroform in the presence of chlorine dioxide, which leads to the safe constructions of carbamoyl chlorides with good-to-high yields and wide substrate scopes. In addition, this method can also be applied to the synthesis of various carbonates.
Abstract A new strategy for synthesis of the 2‐pyridyl carbamates is reported. This strategy exploits a new intramolecular transformation of an acyloxy group from N ‐carbamoyloxypyridinium salts (Reissert–Henze‐type reaction) as the key step. Addition of a silver salt effectively accelerates the intramolecular attack of the carbonyl oxygen at the 2‐position of the pyridine ring. Additionally, a new rearrangement of the acyloxy group, combined with insertion of an ethereal solvent to give pyridin
Abstract A mild, metal‐free synthesis of polyfunctionalized N ‐acyl‐ N , O ‐hemiacetals was developed via the nucleophilic addition of unactivated amides to ketones. The protocol demonstrated a wide substrate scope, with good isolated yields. Additionally, their O ‐acetylated products serve as a precursor of α,α‐difunctionalized N ‐acylimines. An addition reaction of broad scope of nucleophiles to generate N ‐acylimines is also reported. magnified image
In this study, we examined the modification of polypropylene non-woven fabrics (PP NWFs) <i>via</i> a one-step oxidation treatment using photo-activated chlorine dioxide radicals (ClO<sub>2</sub>˙). The oxidised PP NWFs exhibited excellent antibacterial activity against both <i>Escherichia coli</i> (Gram-negative) and <i>Staphylococcus aureus</i> (Gram-positive). The mound structure and antibacterial activity in the modified PP NWFs disappeared upon washing with a polar organic solvent. After wa
A novel and efficient method for the synthesis of 4-substituted 3,5-dinitro-1,4-dihydropyridines by a reaction of β-formyl-β-nitroenamines with aldehydes was developed.
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