Masami Sakamoto

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Organization: Chiba University

Department: Department of Applied Chemistry and Biotechnology, Graduate School of Engineering

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Chemicals
References

Asymmetric Synthesis Involving Reversible Photodimerization of a Prochiral Flavonoid Followed by Crystallization

Co-reporter:Hiroki Ishikawa;Naohiro Uemura;Fumitoshi Yagishita;Nozomi Baba;Yasushi Yoshida;Takashi Mino;Yoshio Kasashima

European Journal of Organic Chemistry 2017 Volume 2017(Issue 46) pp:6878-6881

Publication Date(Web):2017/12/15

DOI:10.1002/ejoc.201701457

Asymmetric synthesis involving photochemical dimerization of a prochiral flavonoid derivative in solution without any chiral source was achieved. Irradiation of ethyl 6-bromochromonecarboxylate in solution efficiently gave a C2-chiral anti-head-to-head dimer in excellent chemical yield with good quantum efficiency (Φ365 = 0.15). X-ray crystallographic analysis revealed that the dimer crystallized as a conglomerate of C2 space group. The crystalline dimer precipitated upon irradiation of the monomer in solution, and indirect racemization of the dimer through a reversible photoreaction in solution and selective crystallization simultaneously occurred to give the C2-chiral dimer in optically active form with up to 80 % ee. Optically active photoproducts could be obtained by simply irradiating achiral materials in solution without an external chiral source.

Reversible changes of axial chirality of naphthamide by photochemical and thermal reactions

Co-reporter:Nobuo Yasuike, Fumitoshi Yagishita, Kazushi Sunaoshi, Yasuhiro Hasegawa, Takashi Mino, Masami Sakamotoa

Journal of Photochemistry and Photobiology A: Chemistry 2016 Volume 331() pp:110-114

Publication Date(Web):1 December 2016

DOI:10.1016/j.jphotochem.2015.07.010

2-Propoxy-1-naphthamide possessing a chiral 2-methylpyrrolidine group exists as a mixture of four diastereomers owing to the rotation of the Ar(CO) and C(O)N bonds. The diastereomers existed in the ratio of 32:32:14:22 in CD3OD. When the MeOH solution of the mixture of diastereomers was irradiated with Pyrex filtered UV light (>290 nm) from a high-pressure mercury lamp, the ratio changed to 27:4:43:26. The diastereomeric ratio was reversibly controlled by irradiation and heat. The change was accurately reflected in the intensity of the CD spectra. Furthermore, the reversible axial chirality was transferred to the optical activity of asymmetric reaction products via the photochemical cycloaddition reaction with 9-cyanoanthracene.

A new class of C2 chiral photodimer ligands for catalytic enantioselective diethylzinc addition to arylaldehydes

Co-reporter:Yuki Ueda, Fumitoshi Yagishita, Hiroki Ishikawa, Yuki Kaji, Nozomi Baba, Yoshio Kasashima, Takashi Mino, Masami Sakamoto

Tetrahedron 2015 Volume 71(Issue 36) pp:6254-6258

Publication Date(Web):9 September 2015

DOI:10.1016/j.tet.2015.06.084

A new class of C2 chiral materials was easily prepared by the photodimerization reaction of (R)-N-phenethyl-2-chromonecarboxamide followed by recrystallization. Reduction of the photodimer gave the corresponding alcohol stereoselectively. Both C2 chiral materials worked effectively as ligands for enantioselective ethylation of arylaldehydes using diethylzinc.

Diastereoselective photodimerization reactions of chromone-2-carboxamides to construct a C2-chiral scaffold

Co-reporter:Fumitoshi Yagishita, Nozomi Baba, Yuki Ueda, Satoshi Katabira, Yoshio Kasashima, Takashi Mino and Masami Sakamoto

Organic & Biomolecular Chemistry 2014 vol. 12(Issue 47) pp:9644-9649

Publication Date(Web):02 Oct 2014

DOI:10.1039/C4OB01827C

Irradiation of three chromone-2-carboxamides with a chiral auxiliary resulted in diastereoselective formation of a C2-chiral anti-HH dimer scaffold. Selection of the solvent polarity and decreasing the temperature resulted in asymmetric induction with up to 84% diastereomeric excess (de).

Deracemization of Quinolonecarboxamides by Dynamic Crystalline Salt Formation and Asymmetric Photoreaction by Using the Frozen Chirality

Co-reporter:Fumitoshi Yagishita;Naoya Takagishi;Hiroki Ishikawa;Yoshio Kasashima;Takashi Mino

European Journal of Organic Chemistry 2014 Volume 2014( Issue 29) pp:6366-6370

Publication Date(Web):

DOI:10.1002/ejoc.201403056

Abstract

An asymmetric photoreaction by using chirality provided by dynamic chiral salt formation was demonstrated. Crystallization of racemic 2-quinolone-3-carboxamide and 2-quinolone-4-carboxamide with enantiopure L-dibenzoyltartaric acid led to deracemization and gave high diastereomeric excess values of the crystalline salts in almost quantitative yield. The axial chirality was retained for a long period of time after the salts were dissolved in cooled solvent. The frozen chirality derived from the chiral salts was effectively transferred to the products by using a typical [2+2] photocycloaddition reaction with alkenes.

Asymmetric transformation by dynamic crystallization of achiral succinimides

Co-reporter:Shoko Hachiya, Yoshio Kasashima, Fumitoshi Yagishita, Takashi Mino, Hyuma Masu and Masami Sakamoto

Chemical Communications 2013 vol. 49(Issue 42) pp:4776-4778

Publication Date(Web):08 Apr 2013

DOI:10.1039/C3CC41678J

Optically active materials could be generated by simple solidification of achiral materials without an external chiral source. When achiral cis-3,4-diphenylsuccinimides were solidified in the presence of a catalytic amount of DBU by evaporating the solvent with stirring, optically active trans-3,4-diphenylsuccinimides were obtained quantitatively with high enantiomeric excesses.

Two-Step Asymmetric Reaction Using the Frozen Chirality Generated by Spontaneous Crystallization

Co-reporter:Fumitoshi Yagishita, Takashi Mino, Tsutomu Fujita, and Masami Sakamoto

Organic Letters 2012 Volume 14(Issue 10) pp:2638-2641

Publication Date(Web):April 30, 2012

DOI:10.1021/ol301033r

N,N-Diallyl-4-methyl-1-propyl-2-quinolone-3-carboxamide afforded chiral crystals of a P21 crystal system by spontaneous crystallization. The molecular chirality in the crystal was retained after the crystals were dissolved in a solvent at a low temperature, and the frozen molecular chirality was effectively transferred to the products by a two-step reaction involving hydrogenation and intermolecular photocycloaddition reactions.

Total Spontaneous Resolution by Deracemization of Isoindolinones

Co-reporter:Fumitoshi Yagishita;Hiroki Ishikawa;Tatsuo Onuki;Shoko Hachiya; Takashi Mino ; Masami Sakamoto

Angewandte Chemie International Edition 2012 Volume 51( Issue 52) pp:13023-13025

Publication Date(Web):

DOI:10.1002/anie.201205097

Total Spontaneous Resolution by Deracemization of Isoindolinones

Co-reporter:Fumitoshi Yagishita;Hiroki Ishikawa;Tatsuo Onuki;Shoko Hachiya; Takashi Mino ; Masami Sakamoto

Angewandte Chemie 2012 Volume 124( Issue 52) pp:13200-13202

Publication Date(Web):

DOI:10.1002/ange.201205097

Kinetic resolution of racemic amines using provisional molecular chirality generated by spontaneous crystallization

Co-reporter:Masami Sakamoto, Kazuyuki Fujita, Fumitoshi Yagishita, Atsushi Unosawa, Takashi Mino and Tsutomu Fujita

Chemical Communications 2011 vol. 47(Issue 14) pp:4267-4269

Publication Date(Web):07 Mar 2011

DOI:10.1039/C1CC00081K

N-(2-methoxy-1-naphthoyl)pyrrolidine afforded chiral crystals by spontaneous crystallization. The molecular chirality in the crystal was retained after dissolving the crystals in a cooled solvent. Kinetic resolution of racemic amines was performed using the provisional chiral molecular conformation derived from chiral crystals.

Exclusive Photodimerization Reactions of Chromone-2-carboxylic Esters Depending on Reaction Media

Co-reporter:Masami Sakamoto, Fumitoshi Yagishita, Masayuki Kanehiro, Yoshio Kasashima, Takashi Mino, and Tsutomu Fujita

Organic Letters 2010 Volume 12(Issue 20) pp:4435-4437

Publication Date(Web):September 24, 2010

DOI:10.1021/ol101734k

The irradiation of chromone-2-carboxylic esters resulted in the stereo- and regioselective formation of C2 chiral anti-HH dimers from the triplet excited state. On the contrary, photolysis in the solid-state gave anti-HT dimers exclusively controlled by molecular arrangement in the crystal.

Generation and amplification of optical activity of axially chiral N-(1-naphthyl)-2(1H)-pyrimidinethione by crystallization

Co-reporter:Masami Sakamoto, Fumitoshi Yagishita, Masaru Ando, Yuich Sasahara, Norifumi Kamataki, Mai Ohta, Takashi Mino, Yoshio Kasashima and Tsutomu Fujita

Organic & Biomolecular Chemistry 2010 vol. 8(Issue 23) pp:5418-5422

Publication Date(Web):24 Sep 2010

DOI:10.1039/C0OB00262C

X-Ray crystallographic analysis of N-(1-naphthyl)-2(1H)-pyrimidinethione revealed that the space group was tetragonal and chiral P43. The rate of racemization due to the C–N bond rotation was considerably influenced by the solvent properties. A nonpolar solvent lowers the ΔG‡value by about 3.0 kcal mol−1 relative to the value in a polar or a protic solvent. The crystallization of racemic axially chiral pyrimidinethione at high temperature led to the chiral breaking of symmetry up to 91% ee.

Photodimerization of chromone

Co-reporter:Masami Sakamoto, Masayuki Kanehiro, Takashi Mino and Tsutomu Fujita

Chemical Communications 2009 (Issue 17) pp:2379-2380

Publication Date(Web):09 Mar 2009

DOI:10.1039/B822829A

Irradiation of the simple chromone (benzo-γ-pyrone) resulted in the formation of two types of dimers, anti-HT (head-to-tail) and trans-fused HTisomers, whose structures were established by X-ray structural analysis.

Asymmetric synthesis of β-lactams using chiral-memory effect on photochemical γ-hydrogen abstraction by thiocarbonyl group

Co-reporter:Masami Sakamoto, Hiroya Kawanishi, Takashi Mino and Tsutomu Fujita

Chemical Communications 2008 (Issue 18) pp:2132-2133

Publication Date(Web):26 Mar 2008

DOI:10.1039/B801524D

Optically active β-lactams were synthesized via photochemical intramolecular γ-hydrogen abstraction reaction of thioimides involving a highly-controlled chiral-memory effect.

Crystallization-induced diastereomer transformation of 2-quinolone-4-carboxamide followed by stereoselective intermolecular photocycloaddition reaction

Co-reporter:Masami Sakamoto, Naoto Sato, Takashi Mino, Yoshio Kasashima and Tsutomu Fujita

Organic & Biomolecular Chemistry 2008 vol. 6(Issue 5) pp:848-850

Publication Date(Web):04 Feb 2008

DOI:10.1039/B719761F

2-Quinolone-4-carboxamide derived from (S)-proline, which exists as a mixture of two diastereomers before crystallization, converged to a single diastereomer by crystallization (CIDT), and the homochirality was transferred by a intermolecular 2 + 2 photocycloaddition reaction with high optical activity.

Diastereoselective photocycloaddition using memory effect of molecular chirality controlled by crystallization

Co-reporter:Masami Sakamoto, Atsushi Unosawa, Shuichiro Kobaru, Yasuhiro Hasegawa, Takashi Mino, Yoshio Kasashima and Tsutomu Fujita

Chemical Communications 2007 (Issue 16) pp:1632-1634

Publication Date(Web):06 Feb 2007

DOI:10.1039/B617888J

Naphthamides derived from L-proline, which exist as a mixture of several diastereomers in solution, converged to single diastereomer by crystallization, and the conformational transformation was controlled after the crystals were dissolved in the solvent at low temperature, where the frozen conformation was retained long enough for subsequent asymmetric reaction.

An asymmetric SNAr reaction using the molecular chirality in a crystal

Co-reporter:Masami Sakamoto, Atsushi Unosawa, Shuichiro Kobaru, Kazuyuki Fujita, Takashi Mino and Tsutomu Fujita

Chemical Communications 2007 (Issue 34) pp:3586-3588

Publication Date(Web):26 Jul 2007

DOI:10.1039/B706426H

An asymmetric SNAr reaction was performed by using molecular chirality generated and amplified by the spontaneous crystallization of achiral naphthamides; the chirality was retained in a cold solution, caused by slow racemization, and was transferred to stable axially chiral materials with high enantiomeric excesses.

Photochemical asymmetric synthesis of phenyl-bearing quaternary chiral carbons using chiral-memory effect on β-hydrogen abstraction by thiocarbonyl group

Co-reporter:Masami Sakamoto, Hiroya Kawanishi, Takashi Mino, Yoshio Kasashima and Tsutomu Fujita

Chemical Communications 2006 (Issue 44) pp:4608-4610

Publication Date(Web):25 Sep 2006

DOI:10.1039/B608513J

Quaternary chiral carbons were effectively generated from tertiary chiral carbons via photochemical intramolecular β-hydrogen abstraction reaction of thioimides involving the highly-controlled chiral-memory effect.

Spontaneous chiral crystallization of achiral materials and absolute asymmetric photochemical transformation using the chiral crystalline environment

Co-reporter:Masami Sakamoto

Journal of Photochemistry and Photobiology C: Photochemistry Reviews 2006 Volume 7(Issue 4) pp:183-196

Publication Date(Web):December 2006

DOI:10.1016/j.jphotochemrev.2006.11.002

Asymmetric transformation using chiral crystals which are derived from chiral crystallization of achiral materials has been summarized. Solid-state photoreaction in the chiral crystal environment provides the reproducible absolute asymmetric synthesis via the cycloaddition reaction, hydrogen abstraction reaction, di-π-methane rearrangement, electrocyclization, and the bond-cleavage reaction. Furthermore, asymmetric syntheses using chiral crystals except solid-state photoreactions such as solid–gas reaction, catalytic asymmetric automultiplication, and the reaction in homogeneous conditions are also reviewed.

Asymmetric Photocycloaddition in Solution of a Chiral Crystallized Naphthamide

Co-reporter:Masami Sakamoto ;Atsushi Unosawa;Shuichiro Kobaru;Ayako Saito;Takashi Mino Dr.;Tsutomu Fujita

Angewandte Chemie 2005 Volume 117(Issue 34) pp:

Publication Date(Web):29 JUL 2005

DOI:10.1002/ange.200501156

Eingefrorene Chiralität: Das achirale Naphthamid 1 kristallisiert als chirales 1*, dessen chirale Molekülkonformation erhalten bleibt („eingefroren“), wenn die Kristalle in kaltem THF gelöst werden. Bei der asymmetrischen Photocycloaddition von 1* an 9-Cyananthracen (9-CNAN) in Lösung entsteht hoch enantioselektiv das Cycloaddukt 2.

Asymmetric Photocycloaddition in Solution of a Chiral Crystallized Naphthamide

Co-reporter:Masami Sakamoto ;Atsushi Unosawa;Shuichiro Kobaru;Ayako Saito;Takashi Mino Dr.;Tsutomu Fujita

Angewandte Chemie International Edition 2005 Volume 44(Issue 34) pp:

Publication Date(Web):29 JUL 2005

DOI:10.1002/anie.200501156

Frozen chirality: Achiral naphthamide 1 can be crystallized to give chiral 1*, whose chiral molecular conformation is retained (“frozen”) after the crystals are dissolved in cold THF. Asymmetric photocycloaddition of 1* with 9-cyanoanthracene (9-CNAN) in solution gives cycloadduct 2 with high enantioselectivity.

Absolute asymmetric synthesis by nucleophilic carbonyl addition using chiral crystals of achiral amides

Co-reporter:Masami Sakamoto, Shuichiro Kobaru, Takashi Mino and Tsutomu Fujita

Chemical Communications 2004 (Issue 8) pp:1002-1003

Publication Date(Web):19 Mar 2004

DOI:10.1039/B315729F

Reaction of the chiral crystals of the achiral amides with n-butyllithium in toluene at −80 °C gave optically active alcohols in 17–84% ee.

Diastereoselective photocycloaddition of axially chiral monothiosuccinimides to 1,1-diphenylethylene

Co-reporter:Masami Sakamoto, Masaki Shigekura, Ayako Saito, Tomoko Ohtake, Takashi Mino and Tsutomu Fujita

Chemical Communications 2003 (Issue 17) pp:2218-2219

Publication Date(Web):24 Jul 2003

DOI:10.1039/B304435A

Photolysis of axially chiral monothiosuccinimides in the presence of diphenylethylene gave spirothietanes effectively, where the cycloaddition took place diastereoselectively by way of the steric effect of the ortho-substituent on the phenyl ring.

Breaking the Symmetry of Axially Chiral N-Aryl-2(1H)-pyrimidinones by Spontaneous Crystallization

Co-reporter:Masami Sakamoto ;Noriyuki Utsumi;Masaru Ando;Mizuho Saeki;Takashi Mino Dr.;Tsutomu Fujita ;Akira Katoh ;Takehiko Nishio ;Choji Kashima

Angewandte Chemie 2003 Volume 115(Issue 36) pp:

Publication Date(Web):17 SEP 2003

DOI:10.1002/ange.200351660

Keine äußere Chiralitätsquelle war für die Spaltung eines axial-chiralen Pyrimidinons in seine Enantiomere erforderlich (siehe Schema). Kristallisation bei hohen Temperaturen lieferte optisch aktives Material mit bis zu 73 % ee. Die Enantiomere konnten mit NaBH₄ hoch enantioselektiv reduziert werden.

Breaking the Symmetry of Axially Chiral N-Aryl-2(1H)-pyrimidinones by Spontaneous Crystallization

Co-reporter:Masami Sakamoto ;Noriyuki Utsumi;Masaru Ando;Mizuho Saeki;Takashi Mino Dr.;Tsutomu Fujita ;Akira Katoh ;Takehiko Nishio ;Choji Kashima

Angewandte Chemie International Edition 2003 Volume 42(Issue 36) pp:

Publication Date(Web):17 SEP 2003

DOI:10.1002/anie.200351660

No outside source of chirality was needed to resolve the racemate of an axially chiral pyrimidinone (see scheme). Crystallization at high temperatures gave optically active material in up to 73 % ee. The resolved product could be reduced with NaBH₄ with high enantioselectivity.

Diastereoselective photodimerization reactions of chromone-2-carboxamides to construct a C2-chiral scaffold

Co-reporter:Fumitoshi Yagishita, Nozomi Baba, Yuki Ueda, Satoshi Katabira, Yoshio Kasashima, Takashi Mino and Masami Sakamoto

Organic & Biomolecular Chemistry 2014 - vol. 12(Issue 47) pp:NaN9649-9649

Publication Date(Web):2014/10/02

DOI:10.1039/C4OB01827C

Kinetic resolution of racemic amines using provisional molecular chirality generated by spontaneous crystallization

Co-reporter:Masami Sakamoto, Kazuyuki Fujita, Fumitoshi Yagishita, Atsushi Unosawa, Takashi Mino and Tsutomu Fujita

Chemical Communications 2011 - vol. 47(Issue 14) pp:NaN4269-4269

Publication Date(Web):2011/03/07

DOI:10.1039/C1CC00081K

Generation and amplification of optical activity of axially chiral N-(1-naphthyl)-2(1H)-pyrimidinethione by crystallization

Co-reporter:Masami Sakamoto, Fumitoshi Yagishita, Masaru Ando, Yuich Sasahara, Norifumi Kamataki, Mai Ohta, Takashi Mino, Yoshio Kasashima and Tsutomu Fujita

Organic & Biomolecular Chemistry 2010 - vol. 8(Issue 23) pp:NaN5422-5422

Publication Date(Web):2010/09/24

DOI:10.1039/C0OB00262C

Asymmetric transformation by dynamic crystallization of achiral succinimides

Co-reporter:Shoko Hachiya, Yoshio Kasashima, Fumitoshi Yagishita, Takashi Mino, Hyuma Masu and Masami Sakamoto

Chemical Communications 2013 - vol. 49(Issue 42) pp:NaN4778-4778

Publication Date(Web):2013/04/08

DOI:10.1039/C3CC41678J

Diastereoselective photocycloaddition using memory effect of molecular chirality controlled by crystallization

Co-reporter:Masami Sakamoto, Atsushi Unosawa, Shuichiro Kobaru, Yasuhiro Hasegawa, Takashi Mino, Yoshio Kasashima and Tsutomu Fujita

Chemical Communications 2007(Issue 16) pp:NaN1634-1634

Publication Date(Web):2007/02/06

DOI:10.1039/B617888J

Asymmetric synthesis of β-lactams using chiral-memory effect on photochemical γ-hydrogen abstraction by thiocarbonyl group

Co-reporter:Masami Sakamoto, Hiroya Kawanishi, Takashi Mino and Tsutomu Fujita

Chemical Communications 2008(Issue 18) pp:NaN2133-2133

Publication Date(Web):2008/03/26

DOI:10.1039/B801524D

Optically active β-lactams were synthesized via photochemical intramolecular γ-hydrogen abstraction reaction of thioimides involving a highly-controlled chiral-memory effect.

Crystallization-induced diastereomer transformation of 2-quinolone-4-carboxamide followed by stereoselective intermolecular photocycloaddition reaction

Co-reporter:Masami Sakamoto, Naoto Sato, Takashi Mino, Yoshio Kasashima and Tsutomu Fujita

Organic & Biomolecular Chemistry 2008 - vol. 6(Issue 5) pp:NaN850-850

Publication Date(Web):2008/02/04

DOI:10.1039/B719761F

Photodimerization of chromone

Co-reporter:Masami Sakamoto, Masayuki Kanehiro, Takashi Mino and Tsutomu Fujita

Chemical Communications 2009(Issue 17) pp:NaN2380-2380

Publication Date(Web):2009/03/09

DOI:10.1039/B822829A

An asymmetric SNAr reaction using the molecular chirality in a crystal

Co-reporter:Masami Sakamoto, Atsushi Unosawa, Shuichiro Kobaru, Kazuyuki Fujita, Takashi Mino and Tsutomu Fujita