The University of Tokyo · Chemistry
Professor Ryo Takita's research lab specializes in the development of innovative catalytic methodologies and selective transformation strategies in organic synthesis. Key research directions include transition-metal-free and earth-abundant metal-catalyzed reactions—particularly those involving indium(III) and zinc-based systems—for enantioselective alkynylation and carbonyl transformations. The lab also focuses on the controlled reduction of amides and hydromagnesiation of enynes, employing tailored hydride sources and in situ-generated reagents. Additionally, the group explores redox-active organic architectures, such as oligothiophene tweezers, for stimuli-responsive behavior and π-dimer formation.
Figures are computed from collected data and may differ slightly.
Asymmetric alkynylation of both aromatic and aliphatic aldehydes using catalytic amounts of In(III)/BINOL is described. Dual activation of both substrates due to the "bifunctional character" of the indium(III) catalyst enables a broad range of substrate generality with high enantioselectivity (83 to >99% ee).
[reaction: see text] A new entry in catalytic alkynylation of carbonyl compounds was developed in which dual activation of both soft nucleophiles (terminal alkynes) and hard electrophiles (aldehydes and ketones) is achieved using an indium(III) catalyst. Preliminary mechanistic studies using in situ IR and NMR spectroscopic analysis are also discussed.
New protocols for controlled reduction of carboxamides to either alcohols or amines were established using a combination of sodium hydride (NaH) and zinc halides (ZnX<sub>2</sub> ). Use of a different halide on ZnX<sub>2</sub> dictates the selectivity, wherein the NaH-ZnI<sub>2</sub> system delivers alcohols and NaH-ZnCl<sub>2</sub> gives amines. Extensive mechanistic studies by experimental and theoretical approaches imply that polymeric zinc hydride (ZnH<sub>2</sub> )<sub>∞</sub> is responsibl
An oligothiophene tweezer molecule, which has two quaterthiophene moieties connected to create an electrochemically activated hinge, has been synthesized. Two-electron oxidation of the tweezer molecule produces an intramolecular pi-dimer between the two oligothiophene moieties at room temperature as confirmed by UV-vis absorption, electrochemistry, and EPR experiments.
A protocol for regio-controlled hydromagnesiation of 1,3-enynes was developed using magnesium hydride that is generated in situ by solvothermal treatment of sodium hydride (NaH) and magnesium iodide (MgI<sub>2</sub> ) in THF. The resulting allenylmagnesium species could be converted into tri- and tetra-substituted allenes by subsequent treatment with various carbon- and silicon-based electrophiles with the aid of CuCN as a catalyst.
A new protocol for the dearylation of arylphosphine oxides was developed using sodium hydride (NaH) in the presence of lithium iodide (LiI). The transient sodium phosphinite could be functionalized with a range of electrophiles in a one-pot fashion.
Organomagnesium compounds, represented by the Grignard reagents, are one of the most classical yet versatile carbanion species which have widely been utilized in synthetic chemistry. These reagents are typically prepared <i>via</i> oxidative addition of organic halides to magnesium metals, <i>via</i> halogen-magnesium exchange between halo(hetero)arenes and organomagnesium reagents or <i>via</i> deprotonative magnesiation of prefunctionalized (hetero)arenes. On the other hand, recent studies hav
Abstract A method for the nucleophilic amination of methoxy arenes was established by using sodium hydride (NaH) in the presence of lithium iodide (LiI). This method offers an efficient route to benzannulated nitrogen heterocycles. Mechanistic studies showed that the reaction proceeds through an unusual concerted nucleophilic aromatic substitution.
(S)-1-Phosphaethenyl-2-diarylphosphanylferrocenes with planar chirality (Fc(CH═PMes*)PAr2: PAr2 = PPh2 (3a), P(1-naphthyl)Ph (3b)) are prepared in high yields from optically active 2-phosphanylferrocenecarboxaldehydes by the phospha-Peterson reactions with Mes*P(Li)SiMe3 in THF. The stereochemistry of 3b is determined by X-ray diffraction analysis. Compounds 3a and 3b readily react with [PtMe2(μ-SMe2)]2 in Et2O to afford dimethyl complexes with bidentate coordination of these ligands (PtMe2(L):
A concise protocol for <i>anti</i>-hydromagnesiation of aryl alkynes was established using 1 : 1 molar combination of sodium hydride (NaH) and magnesium iodide (MgI<sub>2</sub>) without the aid of any transition metal catalysts. The resulting alkenylmagnesium intermediates could be trapped with a series of electrophiles, thus providing facile accesses to stereochemically well-defined functionalized alkenes. Mechanistic studies by experimental and theoretical approaches imply that polar hydride a
We describe a powerful, broadly applicable cross-coupling protocol that enables carbon-carbon bond formation at highly sterically hindered carbon centers (both sp<sup>2</sup> and sp<sup>3</sup>) by employing organocopper reagents under palladium catalysis. Experimental studies and theoretical calculations indicated that the key to the unique reactivity of copper is the relatively low activation energy of the compact transmetalation transition state, due to Cu(i)-Pd(ii) interaction, which is asso
A new entry in direct arylation of heteroarenes using Pd(OAc)2 and 1,10-phenanthroline as a nitrogen-based ligand is reported. The long induction period observed at the initial stage of the reaction was effectively reduced by modification of the catalyst preparation, leading to improved chemical yields (69-92%) and shortening of reaction times (3-10 h).
A simple protocol for copper-catalyzed arene amination using aqueous ammonia without any additional ligands and organic coordinating solvents has been developed. The reaction pathway via a Cu(i)/Cu(iii) mechanism is proposed based on the results of control experiments as well as DFT calculations.
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