Takashi was born in 1981 in Tokyo, Japan. He received his undergraduate education and a master of science at the University of Tokyo under Prof. Koichi Narasaka's guidance. He has obtained his PhD working with Prof. Koichiro Oshima at Kyoto University in 2009, and was a postdoc with Prof. Tobias Ritter at Harvard University. In 2010, he was appointed as Assistant Professor in the Faculty of Science and Engineering at Waseda University. His research program is based on synthetic organic and organometallic chemistry.
The palladium-catalysed Suzuki–Miyaura cross-coupling (SMC) reaction of organohalides and organob... more The palladium-catalysed Suzuki–Miyaura cross-coupling (SMC) reaction of organohalides and organoborons is a reliable method for carbon–carbon bond formation. This reaction involves a base-mediated transmetalation process, but the presence of a base also promotes competitive protodeborylation, which reduces the efficiency. Herein, we established an SMC reaction via Lewis acid-mediated transmetalation of an organopalladium(II) intermediate with organoborons. Experimental and theoretical investigations indicate that the controlled release of the transmetalation-active intermediate enabled base-independent transmetalation under heating conditions and enhanced the applicable scope of this process. This system enabled us to avoid the addition of a base, and thus, rendered substrates with base-sensitive moieties available. Results from this research further expand the overall utility of cross-coupling chemistry.
The palladium-catalyzed Suzuki–Miyaura cross-coupling (SMC) reaction of organohalides and organob... more The palladium-catalyzed Suzuki–Miyaura cross-coupling (SMC) reaction of organohalides and organoborons is a reliable carbon–carbon bond-forming method. This reaction involves a base-mediated transmetalation process, but the presence of a base also promotes competitive protodeborylation, which reduces the efficiency. Herein, we established a base-free SMC reaction via Lewis acid-mediated transmetalation of an organopalladium(II) intermediate with organoborons. Experimental and theoretical investigations indicate that the controlled release of the transmetalation-active intermediate enabled base-free transmetalation under heating conditions and enhanced the applicable scope of this process. This system enabled us to avoid the use of a base, and thus, rendered substrates with base-sensitive moieties available.
A convenient method for the stereoinversion of secondary alcohols, applicable to stereocongested ... more A convenient method for the stereoinversion of secondary alcohols, applicable to stereocongested carbocyclic substrates, is reported. A simple three-step procedure, including triflylation of the hydroxy group, nucleophilic oxygenative displacement by the treatment with aqueous N,N-dimethylformamide (DMF), and methanolysis, allowed for efficient stereoinversion of various substrates, including sugar derivatives, in one pot.
Rhodium-catalyzed transformation of alkyl aryl sulfides into arylboronic acid pinacol esters via ... more Rhodium-catalyzed transformation of alkyl aryl sulfides into arylboronic acid pinacol esters via C-S bond cleavage is reported. In combination with transition-metal-catalyzed sulfanyl group-guided regioselective C-H borylation reactions of alkylthioarenes, this method allows the synthesis of a diverse range of multisubstituted arenes.
Oxytocin (OXT) and arginine vasopressin (AVP) are structurally similar neuropeptide hormones that... more Oxytocin (OXT) and arginine vasopressin (AVP) are structurally similar neuropeptide hormones that function as neurotransmitters in the brain, and have opposite key roles in social behaviors. These peptides bind to their G protein-coupled receptors (OXTR and AVPRs), inducing calcium ion-dependent signaling pathways and endocytosis of these receptors. Because selective agonists and antagonists for these receptors have been developed as therapeutic and diagnostic agents for diseases such as psychiatric disorders, facile methods are in demand for the evaluation of selectivity between these receptors. In this study, we developed a quantitative assay for OXT- and AVP-induced endocytosis of their receptors. The mutated Oplophorus luciferase, nanoKAZ, was fused to OXTR and AVPRs to enable rapid quantification of agonist-induced endocytosis by bioluminescence reduction. Agonist stimulation significantly decreases bioluminescence of nanoKAZ-fused receptors in living cells. Using this system, we evaluated clinically used OXTR antagonist atosiban and a reported pyrazinyltriazole derivative, hereby designated as PF13. Atosiban acted as an antagonist of AVPR1a, as well as an agonist for AVPR1b, whereas PF13 antagonized OXTR more selectively than atosiban, as reported previously. This paper shows a strategy for quantification of agonist-induced endocytosis of OXTR and AVPRs, and confirms its potent utility in the evaluation of agonists and antagonists.
Monodefluoroborylation of polyfluoroalkenes has been achieved in a regioselective manner under mi... more Monodefluoroborylation of polyfluoroalkenes has been achieved in a regioselective manner under mild conditions via copper catalysis. The method has shown an extremely broad scope of substrates, including (difluorovinyl)arenes, tetrafluoroethylene (TFE), (trifluorovinyl)arenes, and trifluoromethylated monofluoroalkenes. The choice of boron source was important for the efficient transformation of (difluorovinyl)arenes; (Bpin)2 was suitable for substrates with an electron-deficient aryl group and (Bnep)2 for those with an electron-rich aryl group. Derivatization of the (fluoroalkenyl)boronic acid esters to the corresponding potassium trifluoroborate salts has rendered the products easily isolable, which greatly improved the synthetic practicality of the monodefluoroborylation reaction. Stoichiometric experiments indicate that the fate of the regioselectivity depends on the mode of β-fluorine elimination, which depends on the substrate. Further transformation of the boryl group has allowed facile preparation of fluoroalkene derivatives as exemplified by the synthesis of a fluoroalkene mimic of atorvastatin, which potently inhibited the enzyme activity of HMG-CoA reductase.
A two-step transformation of α,β-unsaturated carboxylic acids to alkenylboronic esters has been a... more A two-step transformation of α,β-unsaturated carboxylic acids to alkenylboronic esters has been achieved via thioesterification of carboxylic acids followed by rhodium-catalyzed decarbonylative borylation of thioesters. The latter reaction proceeds under mild conditions with broad functional-group tolerance, rendering a wide range of alkenylboronic esters easily accessible.
ipso-Borylation of fluoroarenes has been achieved using an air-stable copper complex as a catalys... more ipso-Borylation of fluoroarenes has been achieved using an air-stable copper complex as a catalyst. Mechanistic studies suggest that the reaction proceeds via an SRN1 mechanism involving a single-electron-transfer (SET) process and not via the typical SNAr mechanism. This method differs from the previously reported nickel/copper-cocatalyzed system in terms of scope of the substrate and has exhibited good scalability. Double and triple ipso-borylations of several di- and trifluoroarenes have been also achieved efficiently, enhancing the synthetic utility of this method.
Transformation of aromatic thioesters into arylboronic esters was achieved efficiently using a rh... more Transformation of aromatic thioesters into arylboronic esters was achieved efficiently using a rhodium catalyst. The broad functional‐group tolerance and mild conditions of the method have allowed for the two‐step decarboxylative borylation of a wide range of aromatic carboxylic acids, including commercially available drugs.
A convenient method for the stereoinversion of secondary alcohols, applicable to stereocongested ... more A convenient method for the stereoinversion of secondary alcohols, applicable to stereocongested carbocyclic substrates, is reported. A simple three-step procedure, including triflylation of the hydroxy group, nucleophilic oxygenative displacement by the treatment with aqueous N,N-dimethylformamide (DMF), and methanolysis, allowed for efficient stereoinversion of various substrates, including sugar derivatives, in one pot.
Rhodium-catalyzed transformation of alkyl aryl sulfides into arylboronic acid pinacol esters via ... more Rhodium-catalyzed transformation of alkyl aryl sulfides into arylboronic acid pinacol esters via C−S bond cleavage is reported. In combination with transition-metal-catalyzed sulfanyl group-guided regioselective C−H borylation reactions of alkylthioarenes, this method allows the synthesis of a diverse range of multisubstituted arenes.
Ni/Cu-catalyzed transformation of fluoroarenes to arylboronic acid pinacol esters via C−F bond cl... more Ni/Cu-catalyzed transformation of fluoroarenes to arylboronic acid pinacol esters via C−F bond cleavage has been achieved. Further versatile derivatization of an arylboronic ester has allowed for the facile two-step conversion of a fluoroarene to diverse functionalized arenes, demonstrating the synthetic utility of the method.
The palladium-catalysed Suzuki–Miyaura cross-coupling (SMC) reaction of organohalides and organob... more The palladium-catalysed Suzuki–Miyaura cross-coupling (SMC) reaction of organohalides and organoborons is a reliable method for carbon–carbon bond formation. This reaction involves a base-mediated transmetalation process, but the presence of a base also promotes competitive protodeborylation, which reduces the efficiency. Herein, we established an SMC reaction via Lewis acid-mediated transmetalation of an organopalladium(II) intermediate with organoborons. Experimental and theoretical investigations indicate that the controlled release of the transmetalation-active intermediate enabled base-independent transmetalation under heating conditions and enhanced the applicable scope of this process. This system enabled us to avoid the addition of a base, and thus, rendered substrates with base-sensitive moieties available. Results from this research further expand the overall utility of cross-coupling chemistry.
The palladium-catalyzed Suzuki–Miyaura cross-coupling (SMC) reaction of organohalides and organob... more The palladium-catalyzed Suzuki–Miyaura cross-coupling (SMC) reaction of organohalides and organoborons is a reliable carbon–carbon bond-forming method. This reaction involves a base-mediated transmetalation process, but the presence of a base also promotes competitive protodeborylation, which reduces the efficiency. Herein, we established a base-free SMC reaction via Lewis acid-mediated transmetalation of an organopalladium(II) intermediate with organoborons. Experimental and theoretical investigations indicate that the controlled release of the transmetalation-active intermediate enabled base-free transmetalation under heating conditions and enhanced the applicable scope of this process. This system enabled us to avoid the use of a base, and thus, rendered substrates with base-sensitive moieties available.
A convenient method for the stereoinversion of secondary alcohols, applicable to stereocongested ... more A convenient method for the stereoinversion of secondary alcohols, applicable to stereocongested carbocyclic substrates, is reported. A simple three-step procedure, including triflylation of the hydroxy group, nucleophilic oxygenative displacement by the treatment with aqueous N,N-dimethylformamide (DMF), and methanolysis, allowed for efficient stereoinversion of various substrates, including sugar derivatives, in one pot.
Rhodium-catalyzed transformation of alkyl aryl sulfides into arylboronic acid pinacol esters via ... more Rhodium-catalyzed transformation of alkyl aryl sulfides into arylboronic acid pinacol esters via C-S bond cleavage is reported. In combination with transition-metal-catalyzed sulfanyl group-guided regioselective C-H borylation reactions of alkylthioarenes, this method allows the synthesis of a diverse range of multisubstituted arenes.
Oxytocin (OXT) and arginine vasopressin (AVP) are structurally similar neuropeptide hormones that... more Oxytocin (OXT) and arginine vasopressin (AVP) are structurally similar neuropeptide hormones that function as neurotransmitters in the brain, and have opposite key roles in social behaviors. These peptides bind to their G protein-coupled receptors (OXTR and AVPRs), inducing calcium ion-dependent signaling pathways and endocytosis of these receptors. Because selective agonists and antagonists for these receptors have been developed as therapeutic and diagnostic agents for diseases such as psychiatric disorders, facile methods are in demand for the evaluation of selectivity between these receptors. In this study, we developed a quantitative assay for OXT- and AVP-induced endocytosis of their receptors. The mutated Oplophorus luciferase, nanoKAZ, was fused to OXTR and AVPRs to enable rapid quantification of agonist-induced endocytosis by bioluminescence reduction. Agonist stimulation significantly decreases bioluminescence of nanoKAZ-fused receptors in living cells. Using this system, we evaluated clinically used OXTR antagonist atosiban and a reported pyrazinyltriazole derivative, hereby designated as PF13. Atosiban acted as an antagonist of AVPR1a, as well as an agonist for AVPR1b, whereas PF13 antagonized OXTR more selectively than atosiban, as reported previously. This paper shows a strategy for quantification of agonist-induced endocytosis of OXTR and AVPRs, and confirms its potent utility in the evaluation of agonists and antagonists.
Monodefluoroborylation of polyfluoroalkenes has been achieved in a regioselective manner under mi... more Monodefluoroborylation of polyfluoroalkenes has been achieved in a regioselective manner under mild conditions via copper catalysis. The method has shown an extremely broad scope of substrates, including (difluorovinyl)arenes, tetrafluoroethylene (TFE), (trifluorovinyl)arenes, and trifluoromethylated monofluoroalkenes. The choice of boron source was important for the efficient transformation of (difluorovinyl)arenes; (Bpin)2 was suitable for substrates with an electron-deficient aryl group and (Bnep)2 for those with an electron-rich aryl group. Derivatization of the (fluoroalkenyl)boronic acid esters to the corresponding potassium trifluoroborate salts has rendered the products easily isolable, which greatly improved the synthetic practicality of the monodefluoroborylation reaction. Stoichiometric experiments indicate that the fate of the regioselectivity depends on the mode of β-fluorine elimination, which depends on the substrate. Further transformation of the boryl group has allowed facile preparation of fluoroalkene derivatives as exemplified by the synthesis of a fluoroalkene mimic of atorvastatin, which potently inhibited the enzyme activity of HMG-CoA reductase.
A two-step transformation of α,β-unsaturated carboxylic acids to alkenylboronic esters has been a... more A two-step transformation of α,β-unsaturated carboxylic acids to alkenylboronic esters has been achieved via thioesterification of carboxylic acids followed by rhodium-catalyzed decarbonylative borylation of thioesters. The latter reaction proceeds under mild conditions with broad functional-group tolerance, rendering a wide range of alkenylboronic esters easily accessible.
ipso-Borylation of fluoroarenes has been achieved using an air-stable copper complex as a catalys... more ipso-Borylation of fluoroarenes has been achieved using an air-stable copper complex as a catalyst. Mechanistic studies suggest that the reaction proceeds via an SRN1 mechanism involving a single-electron-transfer (SET) process and not via the typical SNAr mechanism. This method differs from the previously reported nickel/copper-cocatalyzed system in terms of scope of the substrate and has exhibited good scalability. Double and triple ipso-borylations of several di- and trifluoroarenes have been also achieved efficiently, enhancing the synthetic utility of this method.
Transformation of aromatic thioesters into arylboronic esters was achieved efficiently using a rh... more Transformation of aromatic thioesters into arylboronic esters was achieved efficiently using a rhodium catalyst. The broad functional‐group tolerance and mild conditions of the method have allowed for the two‐step decarboxylative borylation of a wide range of aromatic carboxylic acids, including commercially available drugs.
A convenient method for the stereoinversion of secondary alcohols, applicable to stereocongested ... more A convenient method for the stereoinversion of secondary alcohols, applicable to stereocongested carbocyclic substrates, is reported. A simple three-step procedure, including triflylation of the hydroxy group, nucleophilic oxygenative displacement by the treatment with aqueous N,N-dimethylformamide (DMF), and methanolysis, allowed for efficient stereoinversion of various substrates, including sugar derivatives, in one pot.
Rhodium-catalyzed transformation of alkyl aryl sulfides into arylboronic acid pinacol esters via ... more Rhodium-catalyzed transformation of alkyl aryl sulfides into arylboronic acid pinacol esters via C−S bond cleavage is reported. In combination with transition-metal-catalyzed sulfanyl group-guided regioselective C−H borylation reactions of alkylthioarenes, this method allows the synthesis of a diverse range of multisubstituted arenes.
Ni/Cu-catalyzed transformation of fluoroarenes to arylboronic acid pinacol esters via C−F bond cl... more Ni/Cu-catalyzed transformation of fluoroarenes to arylboronic acid pinacol esters via C−F bond cleavage has been achieved. Further versatile derivatization of an arylboronic ester has allowed for the facile two-step conversion of a fluoroarene to diverse functionalized arenes, demonstrating the synthetic utility of the method.
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