Masanori Shigeno 교수

On the contrary! A rhodium-catalyzed restructuring reaction of 3-arylcyclobutanols to 1-indanols is reported, in which two chiral quaternary carbon centers are formed in a highly enantioselective fashion by a sequence of two contradictory elementary steps, that is, carbon–carbon bond cleavage and carbon–carbon bond formation. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edited or typeset. They are mad

A 1:1 mixture of pseudoenantiomeric aminomethylenehelicene (P)-tetramer and (M)-pentamer formed three states, namely, the heterodouble helices B and C and the random coil A. At high temperatures, A is the most stable. At low temperatures, C is the most stable, and the structural changes from A to the metastable state B to the product C occur, where B and C have pseudoenantiomeric helical structures. Heating then converts C to A. Essentially, all the molecules change their structure from A to B t

Molecular switching is a phenomenon in which the molecular structure reversibly changes in response to external stimulation. It is crucial in biology and is used in various biological sensing applications and responses. In contrast to the well-studied molecular switching involving two or more thermodynamically stable states, switching involving metastable states exhibits notable non-equilibrium thermodynamic properties. Synthetic chiral helicene oligomeric foldamers that exhibit molecular therma

We describe the double-carboxylation of two C-H bonds (i.e., at the benzylic and the β-positions) in 2-alkylheteroarenes using a combination of LiO- t-Bu and CsF. A diverse range of substrates, namely benzothiophene, thiophene, benzofuran, furan, and indole derivatives, are efficiently converted into the doubly carboxylated products. A variety of functionalities (i.e., methyl, methoxy, halogen, cyano, ester, ketone, and amide moieties) are well tolerated.

We report that the organic superbase <i>t</i>-Bu-P4 efficiently catalyzes the amination of methoxy(hetero)arenes with amine nucleophiles such as aniline, indoline, and aminopyridine derivatives. This catalytic reaction is effective for the transformation of electron-deficient methoxyarenes possessing diverse functionalities (carbonyl, cyano, nitro, and halogen) as well as methoxyheteroarenes, including pyrazine, quinoline, isoquinoline, and pyridine derivatives. Intramolecular reactions provide

We herein demonstrate that the combination of LiO-tBu, CsF, and [18]crown-6 efficiently promotes the direct C-H carboxylation of electron-rich heteroarenes (benzothiophene, thiophene, benzofuran, and furan derivatives). A variety of functional groups, including methyl, methoxy, halo, cyano, amide, and keto moieties, are compatible with this system. The reaction proceeds via the formation of a tert-butyl carbonate species.

The organic superbase tBu-P4 catalyzes methoxy-alkoxy exchange reactions on (hetero)arenes with alcohols. The catalytic reaction proceeded efficiently with electron-deficient methoxy(hetero)arenes as well as with a variety of alcohols, including 3-amino-1-propanol, β-citronellol, menthol, and cholesterol. An intramolecular version of this reaction furnished six- and seven-membered ring compounds.

Molecular switching is a phenomenon by which a molecule reversibly changes its structure and state in response to external stimuli or energy. Herein, molecular switching is discussed from thermodynamic and kinetic aspects in terms of energy supply with an emphasis on the thermal switching exhibited by helicene oligomers. It includes the inversion of relative thermodynamic stability induced by temperature changes and molecular thermal hysteresis in a closed system. The thermal phenomenon associat

This paper describes that an amide-base generated in situ from tetramethylammonium fluoride (TMAF) and N(TMS)₃ catalyzes the deprotonative coupling of benzylic C(sp³)-H bonds with carbonyls to form stilbenes. A variety of methylheteroarenes (2-methylbenzothiophene, 2-methylbenzofuran, and 2-, 3-, or 4-methylpyridines) are used as nucleophiles. Application to enamine synthesis using DMF as an electrophile is also shown. The present system is effective for toluenes (4-phenyl-

Sulfonamidohelicene oligomers up to the nonamer level were synthesized by the repeated coupling reactions of a building block. A tetramer formed a helix dimer in 1,3-difluorobenzene, which unfolded to a random coil with heating. This structural change exhibited thermal hysteresis in which different thermal responses were observed in the course of temperature increase and decrease. The feature of the hysteresis was examined under different heating/cooling modes, and the mechanisms are discussed o

Abstract A rhodium‐catalyzed direct alkenylation of 1‐(methylthio)naphthalene has been developed using a thioether directing group. The reaction proceeds selectively at the peri ‐position of the naphthalene ring with no competing ortho C−H activation. Both alkynes and alkenes can be used as the coupling counterparts. The alkenylated products with alkynes can be converted to benzo[ de ]thiochromenes by an iodine mediated cyclization method.

Herein, we report that a combination of LiO‐ t Bu, CsF, and 18‐crown‐6 can be used to carry out the carboxylation of indole derivatives at the C‐2 position under an ambient CO 2 atmosphere. Substrates bearing an electrophilic substituent (i.e., cyano, formyl, benzoyl, phenylsulfonyl, phenylsulfinyl, and chloride) at the C‐3 position are smoothly converted into their corresponding carboxylated products with high functional group compatibility.

1,2,3-Benzodiazaboroles can be conveniently prepared from azobenzenes by a two-step protocol involving electrophilic <i>ortho</i>-borylation with BBr₃ and dialkylative cyclization with the Grignard reagent. The methodology provides a diverse range of products equipped with functionalities from azobenzenes containing substituents (Me, <i>t</i>-Bu, F, Cl, Br, I, and OCF₃) and a series of Grignard reagents (alkyl- and arylmagnesium reagents). Moreover, this study displays the

We describe the catalytic amination of β-(hetero)arylethyl ethers with amines using the organic superbase <i>t</i>-Bu-P4 to obtain β-(hetero)arylethylamines. The reaction has a broad substrate scope and allows the transformations of electron-deficient and electron-neutral β-(hetero)arylethyl ethers with various amines including pyrrole, <i>N</i>-alkylaniline, diphenylamine, aniline, indole, and indoline derivatives. Mechanistic studies indicate a two-reaction pathway of MeOH elimination from the

We herein propose that the catalytic concerted S_NAr reaction is a powerful method to prepare functionalized aromatic scaffolds. Classic stepwise S_NAr reactions involving addition/elimination processes require the use of electron-deficient aromatic halides to stabilize Meisenheimer intermediates, despite their widespread use in medicinal chemistry research. Recent efforts have been made to develop concerted S_NAr reactions involving a single transition state, allow