Tokiwakai Group

Iwaki, Japan

Tokiwakai Group

Iwaki, Japan
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Chennapuram M.,Muroran Institute of Technology | Subba Reddy U.V.,Muroran Institute of Technology | Seki C.,Muroran Institute of Technology | Okuyama Y.,Tohoku University | And 5 more authors.
European Journal of Organic Chemistry | Year: 2017

A series of hybrid-type squaramide-fused amino alcohol (SFAA) catalysts were synthesized, and their catalytic efficiency in the enantioselective nitro-aldol reaction of various isatins with nitromethane has been described. This transformation afforded chiral 3-substituted 3-hydroxyoxindoles in excellent chemical yields (up to 99 %) with high enantioselectivities (up to 95 % ee). The resulting chiral 3-hydroxyoxindoles can be further used as synthetic precursors for the synthesis of several natural products that have a broad spectrum of fascinating biological activities. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim


Chennapuram M.,Muroran Institute of Technology | Subba Reddy U.V.,Muroran Institute of Technology | Seki C.,Muroran Institute of Technology | Okuyama Y.,Tohoku University | And 5 more authors.
European Journal of Organic Chemistry | Year: 2017

The hybrid-type squaramide-fused amino alcohol (SFAA) containing both a Brønsted basic site and a hydrogen-bonding site in the molecule showed high catalytic activity as an organocatalyst in the enantioselective Diels–Alder (DA) reactions of 3-hydroxy-2-pyridones with maleimides to afford chiral endo-4-hydroxy-2-azabicyclo[2.2.2]octanes (4-hydroxyisoquinuclidines) with excellent chemical yields and enantioselectivities (up to 95 % yield and 98 % ee). In particular, the use of 4-brominated 2-pyridones afforded the corresponding chiral 4-hydroxyisoquinuclidines with both excellent chemical yields and enantioselectivities (95 %, 98 % ee) with an opposite absolute stereochemistry in comparison with the chiral endo-DA adducts obtained from the reactions performed with common 3-hydroxy-2-pyridones. The DA adducts obtained could be used as synthetic precursors for several natural products that have a broad spectrum of fascinating biologically activities. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim


Subba Reddy U.V.,Muroran Institute of Technology | Chennapuram M.,Muroran Institute of Technology | Seki K.,Muroran Institute of Technology | Seki C.,Muroran Institute of Technology | And 7 more authors.
European Journal of Organic Chemistry | Year: 2017

Enantioselective crossed aldol reactions of isatin derivatives and acetaldehyde have been developed with a series of simple diamino alcohol catalysts to afford 3-substituted 3-hydroxyindolin-2-ones in high chemical yields (up to 95 %) and optical purities (up to 92 % ee). The synthetic potential of the present protocol has been demonstrated by concise, enantioselective, protecting-group-free, and transition metal-free total syntheses of antitumor and antiviral agents with the tryptanthrin architecture, that is, phaitanthrin B and cephalanthrin A, along with the biologically active indolidine alkaloids chimonamidine and donaxaridine as well as the formal synthesis of CPC-1. The highly enantioselective outcome of this catalytic crossed aldol reaction was evaluated by calculating the Gibbs free energies of the possible transition states. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim


Otsuki T.,Muroran Institute of Technology | Kumagai J.,Muroran Institute of Technology | Kohari Y.,Muroran Institute of Technology | Okuyama Y.,Tohoku Pharmaceutical University | And 12 more authors.
European Journal of Organic Chemistry | Year: 2015

The catalytic activity of a simple amino alcohol that contains a bulky super silyl group [i.e., tris(trimethylsilyl)silyl (TTMSS)] bonded to the oxygen atom at the γ-position along with a primary amine moiety was examined in the enantioselective 1,3-dipolar cycloaddition of nitrones to α,β-unsaturated aldehydes. The organocatalyst successfully provided optically active isoxazolidines in good chemical yields (up to 86 %) with excellent diastereoselectivities (endo/exo, up to 96:4) and enantioselectivities (up to 97 % ee). Furthermore, the obtained isoxazolidines were easily converted into γ-amino diols that contain three contiguous stereogenic centers. © 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.


Uwai K.,Muroran Institute of Technology | Okuyama Y.,Tohoku Pharmaceutical University | Nakano H.,Muroran Institute of Technology | Furukawa K.,Tohoku Pharmaceutical University | And 6 more authors.
Biocatalysis and Agricultural Biotechnology | Year: 2014

The biotransformation of organic compounds using the larvae of the Japanese rhinoceros beetle (Allomyrina dichotoma) as a biocatalyst is described. When phenyl alkanediones were administered by mouth (p.o) or subcutaneous injection (s.c) to the beetle, asymmetric reduction occurred to yield the corresponding diols in varying optical yields: 1-phenyl-1,2-propandione or 1-phenyl-1,3-butanedione reduced to (1R,2S)- and (1S,2S)-1,2-phenylpropanediols in high optical yields or (1R,3S)- and (1R,3R)-1-phenyl-1,3-butanediols in low to high optical yields, respectively. By administrating 1-phenyl-1-propanone, 1-phenyl-1-butanone or 4-phenyl-2-butanone, redox reactions occurred to give 1-phenyl-1,2-propanediols or 1-phenyl-1,3-butanediols in lower optical yields. The administrations of β-ionone and cinnamyl chloride resulted in regioselective allylic oxidations producing enone and cinnamic acid, respectively. However, when (R)-(-)-carvone was administered, regiospecific dihydroxylation at the isopropenyl group occurred to give (4R,8R)- and (4R,8S)-8,9-dihydroxy-8,9-dihydrocarvone as diastereoisomers. These results appear to demonstrate similar reaction tendency with the case of a microorganism. It is possible that these reactions were due in part to bacteria in the intestine of the larva: however, regio- and stereoselectivities of the reactions were sometimes unique. Thus, it is supposed that these biotransformations were accomplished by the ensemble of the larva's own enzymes with several bacteria. The results obtained in this study might show the possibility of using such enzymes derived from insects, including beetle larvae, as a biocatalyst. © 2014 Elsevier Ltd.


Ogasawara A.,Muroran Institute of Technology | Subba Reddy U.V.,Muroran Institute of Technology | Seki C.,Muroran Institute of Technology | Okuyama Y.,Tohoku University | And 4 more authors.
Tetrahedron Asymmetry | Year: 2016

Optically active 2-azanorbornane-based organocatalysts were designed and synthesized, and the catalytic activity of these catalysts in enantioselective aldol reactions of isatins with ketones was investigated. Among these catalysts, 2-azanorbornylmethanol showed the best catalytic activity to afford the corresponding aldol product in excellent chemical yield (up to 95%) and with moderate stereoselectivity (up to 64% ee, up to syn:anti = 36:64). © 2016 Elsevier Ltd


Kumagai J.,Muroran Institute of Technology | Otsuki T.,Muroran Institute of Technology | Subba Reddy U.V.,Muroran Institute of Technology | Kohari Y.,Muroran Institute of Technology | And 7 more authors.
Tetrahedron Asymmetry | Year: 2015

Simple chiral triethylsilyl-amino alcohol organocatalysts containing a bulky triethylsilyl group on the oxygen atom at the γ-position were designed and synthesized as new organocatalysts for enantioselective Diels-Alder reactions of anthrones with maleimides to produce chiral hydroanthracene Diels-Alder adducts in up to 99% yield and with up to 94% ee. © 2015 Elsevier Ltd. All rights reserved.


Sakuta Y.,Muroran Institute of Technology | Kohari Y.,Muroran Institute of Technology | Hutabarat N.D.M.R.,Muroran Institute of Technology | Uwai K.,Muroran Institute of Technology | And 8 more authors.
Heterocycles | Year: 2012

The enantioselective Diels-Alder reactions of 1,2-dihydropyridines with acroleins using a chiral primary amino silyl ether organocatalyst afforded chiral isoquinuclidines with good chemical yields and excellent enantioselectivities (up to 70% and up to 99% ee). © 2012 The Japan Institute of Heterocyclic Chemistry.


Sano K.,Muroran Institute of Technology | Kohari Y.,Muroran Institute of Technology | Nakano H.,Muroran Institute of Technology | Seki C.,Muroran Institute of Technology | And 4 more authors.
Synthetic Communications | Year: 2016

Synthesis of bicyclic compounds was achieved via a lipase-catalyzed, stereoselective, domino Michael-aldol reaction of 2-methyl-1,3-cycloalkanedione and methyl vinyl ketone. Appropriate reaction conditions, including the type of enzyme, solvent, and temperature, were determined. In addition, the effects of solvent polarity and addtives were investigated. The reaction proceeded in the presence of lipase AS in a solution of 20% acetone in dimethylsulfoxide (DMSO) at 10 °C for 8 days, followed by the addition of p-toluenesulfonic acid (TsOH) to afford bicyclic compounds in 51-83% yields with moderate stereoselectivity. Although this domino Michael-aldol reaction showed only moderate stereoselectivity, even with the acid-supported enhancement of the reaction, these results represent potential new applications for lipase. © 2016 Taylor & Francis Group, LLC.

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