Publications by authors named "Shogo Kamo"

13 Publications

  • Page 1 of 1

Total Synthesis of Cochlearol B via Intramolecular [2+2] Photocycloaddition.

Angew Chem Int Ed Engl 2021 Sep 17. Epub 2021 Sep 17.

Hoshi University, Synthetic Medicinal Chemistry, 2-4-41, Ebara, 142-8501, Shinagawa-ku, JAPAN.

Herein, we describe the first total synthesis of cochlearol B, a meroterpenoid natural product featuring a 4/5/6/6/6-fused pentacyclic structure. Key steps, oxidative cyclization and subsequent intramolecular [2+2] photocycloaddition, which constructed the pentacyclic structure in highly stereoselective manner, allowed efficient access to cochlearol B with the longest linear sequence of 16 steps, and in 9% overall yield. Single-crystal X-ray crystallographic analysis clearly confirmed the stereochemistry of cochlearol B.
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http://dx.doi.org/10.1002/anie.202110556DOI Listing
September 2021

Convergent total synthesis of corallocin A.

Org Biomol Chem 2021 Jun;19(23):5127-5132

Department of Synthetic Medicinal Chemistry, Faculty of Pharmaceutical Sciences, Hoshi University, 2-4-41 Ebara, Shinagawa-ku, Tokyo 142-8501, Japan.

The first total synthesis of corallocin A is described herein. The Suzuki coupling reaction as a key step proceeded with high stereoselectivity and in good yield. Robust transformations, including Vilsmeier-Haack formylation and Wittig reaction, allowed for effective access to corallocin A.
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http://dx.doi.org/10.1039/d1ob00451dDOI Listing
June 2021

Synthesis and Cytotoxic Evaluation of -Alkyl-2-halophenazin-1-ones.

ACS Omega 2020 Oct 16;5(42):27667-27674. Epub 2020 Oct 16.

Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, 2641 Yaamazaki, Noda, Chiba 278-8510, Japan.

In this study, the synthesis of -alkyl-2-halophenazin-1-ones has been established. Six -alkyl-2-halophenazin-1-ones, including WS-9659 B and marinocyanins A and B, were synthesized by the direct oxidative condensation of 4-halo-1,2,3-benzenetriol with the corresponding -alkylbenzene-1,2-diamines. One of the most significant features of the present method is that it can be successfully applied to the synthesis of -alkyl-2-chlorophenazin-1-ones. The traditional chlorination of -alkyl-phenazin-1-ones with -chlorosuccinimide selectively occurs at the 4-position to afford the undesired -alkyl-4-chlorophenazin-1-ones. Our synthetic route successfully circumvents this problem, culminating in the first chemical synthesis of WS-9659 B. The cytotoxicity of six -alkyl-2-halophenazin-1-ones and three -alkylphenazin-1-ones against human promyelocytic leukemia HL-60, human lung cancer A549, and normal MRC-5 cells was evaluated. Among the compounds tested in this study, 2-chloropyocyanin possesses significant selectivity toward A549 cells. The cytotoxic evaluation provides structural insights into the potency and selectivity of these compounds for cancer cells.
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http://dx.doi.org/10.1021/acsomega.0c04253DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7594318PMC
October 2020

Investigation on the Epoxidation of Piperitenone, and Structure-activity Relationships of Piperitenone Oxide for Differentiation-inducing Activity.

J Oleo Sci 2020 Aug 9;69(8):951-958. Epub 2020 Jul 9.

Department of Applied Biological Science, Tokyo University of Science.

Piperitenone oxide, a major chemical constituent of the essential oil of spearmint, Mentha spicata, induces differentiation in human colon cancer RCM-1 cells. In this study, piperitenone oxide and trans-piperitenone dioxide were prepared as racemic forms by epoxidation of piperitenone. The relative configuration between two epoxides in piperitenone dioxide was determined to be trans by H NMR analysis and nuclear Overhauser effect spectroscopy (NOESY) in conjunction with density functional theory (DFT) calculations. Optical resolution of (±)-piperitenone oxide by high-performance liquid chromatography (HPLC) using a chiral stationary phase (CSP) afforded both enantiomers with over 98% enantiomeric excess (ee). Evaluation of the differentiation-inducing activity of the synthetic compounds revealed that the epoxide at C-1 and C-6 in piperitenone oxide is important for the activity, and (+)-piperitenone oxide has stronger activity than (-)-piperitenone oxide. The results obtained in this study provide new information on the application of piperitenone oxide and spearmint for differentiation-inducing therapy. Furthermore, natural piperitenone oxide was isolated from M. spicata. The enantiomeric excess of the isolated natural piperitenone oxide was 66% ee. Epoxidation of piperitenone with hydrogen peroxide proceeded in a phosphate buffer under weak basic conditions to give (±)-piperitenone oxide. These results suggest that the nonenzymatic epoxidation of piperitenone, which causes a decrease in the enantiomeric excess of natural piperitenone oxide, is accompanied by an enzymatic epoxidation in the biosynthesis of piperitenone oxide.
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http://dx.doi.org/10.5650/jos.ess19278DOI Listing
August 2020

Synthetic and Biological Studies of Juglorubin and Related Naphthoquinones.

J Org Chem 2019 11 23;84(21):13957-13966. Epub 2019 Oct 23.

Department of Applied Biological Science, Faculty of Science and Technology , Tokyo University of Science , 2641 Yamazaki , Noda, Chiba 278-8510 , Japan.

Juglorubin, juglorescein, and juglocombins A/B are naturally occurring naphthoquinone dimers isolated from sp. These dimers are proposed to be biogenetically derived from juglomycin C, a monomeric naphthoquinone isolated from the same sp. In this study, the dimerization of a juglomycin C derivative, a key step in the total syntheses of these natural products, was investigated. Juglorubin was synthesized from the minor product of the dimerization via the formation of the juglocombin A/B stereoisomers. A mechanism for the dimerization reaction as well as a plausible biosynthetic pathway to obtain juglorubin from juglomycin C are proposed. Furthermore, the antibacterial and cytotoxic activities of five synthetic compounds were evaluated. Among the compounds tested in this study, 1'--methyljuglocombin B dimethyl ester and juglomycin C exhibited antibacterial activity against . 1'--Methyljuglocombin B dimethyl ester and juglomycin C showed cytotoxicity against human colon carcinoma HCT116 cells and human leukemia HL-60 cells. 1'--Methyljuglocombin B dimethyl ester exhibited cytotoxicity against human normal MRC-5 cells as strong as that against human cancer cells. In contrast, juglomycin C was less toxic against normal MRC-5 cells, indicating a significant selectivity toward cancer cells.
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http://dx.doi.org/10.1021/acs.joc.9b02119DOI Listing
November 2019

Synthesis of nucleotide analogues, EFdA, EdA and EdAP, and the effect of EdAP on hepatitis B virus replication.

Biosci Biotechnol Biochem 2020 Feb 7;84(2):217-227. Epub 2019 Oct 7.

Department of Applied Biological Science, Tokyo University of Science, Chiba, Japan.

4'-Ethynyl-2-fluoro-2'-deoxyadenosine (EFdA) and 4'-ethynyl-2'-deoxyadenosine (EdA) are nucleoside analogues which inhibit human immunodeficiency virus type 1 (HIV-1) reverse transcriptase. EdAP, a cyclosaligenyl (cycloSal) phosphate derivative of EdA, inhibits the replication of the influenza A virus. The common structural feature of these compounds is the ethynyl group at the 4'-position. In this study, these nucleoside analogues were prepared by a common synthetic strategy starting from the known 1,2-di--acetyl-D-ribofuranose. Biological evaluation of EdAP revealed that this compound reduced hepatitis B virus (HBV) replication dose-dependently without cytotoxicity against host cells tested in this study.
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http://dx.doi.org/10.1080/09168451.2019.1673696DOI Listing
February 2020

Total Syntheses of Pyocyanin, Lavanducyanin, and Marinocyanins A and B.

Org Lett 2019 09 28;21(18):7311-7314. Epub 2019 Aug 28.

Department of Applied Biological Science, Faculty of Science and Technology , Tokyo University of Science , 2641 Yamazaki , Noda , Chiba 278-8510 , Japan.

Total syntheses of pyocyanin, lavanducyanin, and marinocyanins A and B have been accomplished. The -substituted phenazin-1-one skeleton, a common framework of these natural products, was constructed through the oxidative condensation of pyrogallol with -substituted benzene-1,2-diamine under an oxygen atmosphere in a single step. Regioselective bromination with -bromosuccinimide at the C-2 position of -alkylated phenazin-1-ones afforded brominated natural products.
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http://dx.doi.org/10.1021/acs.orglett.9b02601DOI Listing
September 2019

Unified Approach toward Syntheses of Juglomycins and Their Derivatives.

ACS Omega 2019 Jul 5;4(7):11737-11748. Epub 2019 Jul 5.

Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan.

A unified and common intermediate strategy for syntheses of juglomycins and their derivatives is reported. The use of a 1,4-dimethoxynaphthalene derivative as a key intermediate enabled easy access to various juglomycin derivatives. In this study, juglomycins A-D, juglomycin C amide, khatmiamycin and its 4-epimer, and the structure proposed for juglomycin Z were synthesized from this intermediate. The absolute configuration of natural khatmiamycin has been established to be 3,4 through our synthesis. Unfortunately, the spectroscopic data for synthetic juglomycin Z were not consistent with the data reported for the natural one, strongly suggesting a structural misassignment.
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http://dx.doi.org/10.1021/acsomega.9b01376DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6682012PMC
July 2019

Synthesis, antibacterial and cytotoxic evaluation of flavipucine and its derivatives.

Bioorg Med Chem Lett 2019 06 26;29(11):1390-1394. Epub 2019 Mar 26.

Department of Applied Biological Science, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan. Electronic address:

The antibacterial and cytotoxic activity of seven racemic lactams and both enantiomers of flavipucine were evaluated. Of the compounds tested in this study, flavipucine and phenylflavipucine displayed bactericidal activity against Bacillus subtilis. These results indicate that the pyridione epoxide moiety is a pharmacophore for antibacterial activity against B. subtilis. Flavipucine showed cytotoxic activity against several cancer cells. The cytotoxic activity of flavipucine against human leukemia HL-60 cells is as strong as that of SN-38, the active metabolite of irinotecan. In contrast, the cytotoxic activity of flavipucine against nonneoplastic HEK293 cells and human normal MRC-5 cells is weaker than that of SN-38. No significant differences in the biological activity of the racemates or enantiomers of flavipucine were observed.
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http://dx.doi.org/10.1016/j.bmcl.2019.03.034DOI Listing
June 2019

Synthesis and Photochemical Properties of Axially Chiral Bis(dinaphthofuran).

J Org Chem 2018 12 8;83(23):14610-14616. Epub 2018 Nov 8.

Graduate School for Life and Environmental Sciences , Kyoto Prefectural University , 1-5 Shimogamo Hangi-cho , Sakyo-ku, Kyoto 606-8522 , Japan.

Both enantiomers of axially chiral bis(dinaphthofuran) were prepared in only two steps from 1'-hydroxy-4'-methoxy-2,2'-binaphthalenyl-1,4-dione, followed by optical resolution via high-performance liquid chromatography (HPLC) using a chiral stationary phase (CSP). The absolute configurations were determined by comparison of experimental and calculated vibrational circular dichroism (VCD) spectra. Synthetic bis(dinaphthofuran) exhibited a broad and unstructured emission derived from an intramolecular excimer in both solution and solid state. The methylene bridge brings both chromophores close to each other and induces significant changes in the photophysical behavior. Chiral bis(dinaphthofuran) displayed a bathochromic shift in emission, as compared to the racemic mixture in the solid state. Furthermore, the compounds showed high circularly polarized luminescence (CPL) with a dissymmetry factor ( g) of 10 at 405 nm upon excitation at 265 nm in a methanol solution. This compound serves as a model for the design and synthesis of organic materials having CPL activity.
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http://dx.doi.org/10.1021/acs.joc.8b02424DOI Listing
December 2018

Bioinspired Synthesis of Juglorubin from Juglomycin C.

Org Lett 2018 02 24;20(4):1082-1085. Epub 2018 Jan 24.

Graduate School for Life and Environmental Sciences, Kyoto Prefectural University , 1-5 Shimogamo Hangi-cho, Sakyo-ku, Kyoto 606-8522, Japan.

In this paper, the synthesis of juglorubin, a natural red dye, from juglomycin C, a plausible biogenetic precursor, is reported. Sequential intermolecular and intramolecular Michael additions of juglomycin C, oxidation, and skeletal transformation proceeded in phosphate buffer to afford an undehydrated derivative of juglorubin. Subsequent dehydration of the secondary alcohol afforded juglorubin. The one-pot synthesis of juglorubin from juglomycin C was also achieved. The photophysical properties of synthetic juglorubin and its derivatives were evaluated.
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http://dx.doi.org/10.1021/acs.orglett.7b04051DOI Listing
February 2018

Skeletal Rearrangements of Polycyclic α-Ketols.

Org Lett 2017 01 3;19(2):301-303. Epub 2017 Jan 3.

Graduate School of Life and Environmental Sciences, Kyoto Prefectural University , Kyoto 606-8522, Japan.

It has been proposed that prekinamycin and kinobscurinone may biogenetically isomerize to isoprekinamycin and prefluostatin, respectively, through the corresponding bridgehead α-ketol intermediates. In this transformation, the 6-5 ring system is converted into a 5-6 ring system via an α-ketol rearrangement. In this report, the skeletal rearrangement of polycyclic α-ketols inspired by this hypothetical biosynthetic transformation is reported. In addition, an unexpected rearrangement from dibenzo[b]fluorene to benzo[g]chromene is also reported.
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http://dx.doi.org/10.1021/acs.orglett.6b03541DOI Listing
January 2017

Total Syntheses of Juglorescein and Juglocombins A and B.

Angew Chem Int Ed Engl 2016 08 27;55(35):10317-20. Epub 2016 Jul 27.

Graduate School for Life and Environmental Sciences, Kyoto Prefectural University, 1-5 Shimogamo Hanki-cho, Sakyo-ku, Kyoto, 606-8522, Japan.

Total syntheses of juglorescein and juglocombins A and B are reported. The highly oxygenated 6/6/5/6/6-fused pentacyclic ring system of these natural products was constructed through a bioinspired dimerization of 1,4-naphthoquinone. Notably, five new stereogenic centers were constructed in a single step by the dimerization reaction. The epoxide intermediate obtained from the dimerization was successfully converted into juglocombins A and B through photoinduced reduction of the epoxide, dehydration, and conversion of the resultant quinone into a hydroquinone derivative. The same epoxide intermediate was also converted into a dicarboxylic acid, which was transformed into juglorescein through intramolecular lactonization, hydrolysis of the resulting lactone, and removal of the protecting groups. Furthermore, the relative and absolute configurations of juglorescein and juglocombins A and B were determined.
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http://dx.doi.org/10.1002/anie.201604765DOI Listing
August 2016
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