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Fujioka H. Development of New Innovative Synthetic Organic Chemistry Using Lone Pairs of Oxygen Atoms. Chem Pharm Bull (Tokyo) 2020; 68:907-945. [PMID: 32999145 DOI: 10.1248/cpb.c20-00178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Oxygen atoms have a lone pair of electrons, so they have high chelation ability, high nucleophilic ability, stabilizing ability of adjacent cations, and take a chelate or oxocarbenium ion structure with Lewis acids and metals. I took advantage of these properties to develop three new reactions, 1) asymmetric synthesis of chiral quaternary carbon centers, 2) asymmetric synthesis using acetal functions, and 3) organic chemistry using acetal-type reactive salt chemical species, and applied them to biologically active natural products synthesis. New reactions described here are all innovative and useful for natural products synthesis. In particular, the first asymmetric synthesis of fredericamycin A, and concise asymmetric synthesis of anthracycline antibiotics, scyphostatin, (+)-Sch 642305, (-)-stenine, clavolonine, (+)-rubrenolide, (+)-rubrynolide, (+)-centrolobine, and decytospolide A and B, etc., are noteworthy. Furthermore, since reactions using acetal-type reactive salt chemical species allow the coexistence of functional groups that normally cannot coexist, the reactions using reactive salts have potential to change the retrosynthesis planned based on conventional reactions.
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Affiliation(s)
- Hiromichi Fujioka
- The Institute of Scientific and Industrial Research, Osaka University
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2
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Kawajiri T, Kato M, Nakata H, Goto R, Aibara SY, Ohta R, Fujioka H, Sajiki H, Sawama Y. Chemoselective Nucleophilic Functionalizations of Aromatic Aldehydes and Acetals via Pyridinium Salt Intermediates. J Org Chem 2019; 84:3853-3870. [DOI: 10.1021/acs.joc.8b02965] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Takahiro Kawajiri
- Laboratory of Organic Chemistry, Gifu Pharmaceutical University, 1-25-4, Daigaku-nishi, Gifu 501-1196, Japan
| | - Maho Kato
- Laboratory of Organic Chemistry, Gifu Pharmaceutical University, 1-25-4, Daigaku-nishi, Gifu 501-1196, Japan
| | - Hiroki Nakata
- Laboratory of Organic Chemistry, Gifu Pharmaceutical University, 1-25-4, Daigaku-nishi, Gifu 501-1196, Japan
| | - Ryota Goto
- Laboratory of Organic Chemistry, Gifu Pharmaceutical University, 1-25-4, Daigaku-nishi, Gifu 501-1196, Japan
| | - Shin-yo Aibara
- Laboratory of Organic Chemistry, Gifu Pharmaceutical University, 1-25-4, Daigaku-nishi, Gifu 501-1196, Japan
| | - Reiya Ohta
- Graduate School of Pharmaceutical Sciences, Osaka University, 1-6, Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Hiromichi Fujioka
- Graduate School of Pharmaceutical Sciences, Osaka University, 1-6, Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Hironao Sajiki
- Laboratory of Organic Chemistry, Gifu Pharmaceutical University, 1-25-4, Daigaku-nishi, Gifu 501-1196, Japan
| | - Yoshinari Sawama
- Laboratory of Organic Chemistry, Gifu Pharmaceutical University, 1-25-4, Daigaku-nishi, Gifu 501-1196, Japan
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Yasukawa N, Kanie T, Kuwata M, Monguchi Y, Sajiki H, Sawama Y. Palladium on Carbon-Catalyzed Benzylic Methoxylation for Synthesis of Mixed Acetals and Orthoesters. Chemistry 2017; 23:10974-10977. [DOI: 10.1002/chem.201702278] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Indexed: 12/18/2022]
Affiliation(s)
- Naoki Yasukawa
- Laboratory of Organic Chemistry; Gifu Pharmaceutical University; 1-25-4 Daigaku-nishi Gifu 501-1196 Japan
| | - Takafumi Kanie
- Laboratory of Organic Chemistry; Gifu Pharmaceutical University; 1-25-4 Daigaku-nishi Gifu 501-1196 Japan
| | - Marina Kuwata
- Laboratory of Organic Chemistry; Gifu Pharmaceutical University; 1-25-4 Daigaku-nishi Gifu 501-1196 Japan
| | - Yasunari Monguchi
- Laboratory of Organic Chemistry; Gifu Pharmaceutical University; 1-25-4 Daigaku-nishi Gifu 501-1196 Japan
| | - Hironao Sajiki
- Laboratory of Organic Chemistry; Gifu Pharmaceutical University; 1-25-4 Daigaku-nishi Gifu 501-1196 Japan
| | - Yoshinari Sawama
- Laboratory of Organic Chemistry; Gifu Pharmaceutical University; 1-25-4 Daigaku-nishi Gifu 501-1196 Japan
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Maegawa T, Nogata M, Hirose Y, Ohgami S, Nakamura A, Miki Y, Fujioka H. Transformation of Methylene Acetals to Bromoformates with a Combination of Trimethyl(phenylthio)silane and N-Bromosuccinimide. J Org Chem 2017. [DOI: 10.1021/acs.joc.7b00776] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Tomohiro Maegawa
- School
of Pharmaceutical Sciences, Kindai University, Higashi-osaka, Osaka 577-8502, Japan
| | - Misa Nogata
- School
of Pharmaceutical Sciences, Kindai University, Higashi-osaka, Osaka 577-8502, Japan
| | - Yuuka Hirose
- School
of Pharmaceutical Sciences, Kindai University, Higashi-osaka, Osaka 577-8502, Japan
| | - Shun Ohgami
- School
of Pharmaceutical Sciences, Kindai University, Higashi-osaka, Osaka 577-8502, Japan
| | - Akira Nakamura
- School
of Pharmaceutical Sciences, Kindai University, Higashi-osaka, Osaka 577-8502, Japan
| | - Yasuyoshi Miki
- School
of Pharmaceutical Sciences, Kindai University, Higashi-osaka, Osaka 577-8502, Japan
- Research
Organization of Science and Technology, Research Center for Drug Discovery and Pharmaceutical Science, Nojihigashi, Kusatsu, Shiga 525-8577, Japan
| | - Hiromichi Fujioka
- Graduate
School of Pharmaceutical Sciences, Osaka University, Suita, Osaka 565-0871, Japan
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Gardner KD, Wiemer DF. Selective Prenylation of Protected Phenols for Synthesis of Pawhuskin A Analogues. J Org Chem 2016; 81:1585-92. [DOI: 10.1021/acs.joc.5b02756] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Kevyn D. Gardner
- Department
of Chemistry, University of Iowa, Iowa City, Iowa 52242-1294, United States
| | - David F. Wiemer
- Department
of Chemistry, University of Iowa, Iowa City, Iowa 52242-1294, United States
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6
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Okitsu T, Nakata K, Nishigaki K, Michioka N, Karatani M, Wada A. Iodocyclization of Ethoxyethyl Ethers to Ynamides: An Immediate Construction to Benzo[b]furans. J Org Chem 2014; 79:5914-20. [DOI: 10.1021/jo500903y] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Takashi Okitsu
- Department of Organic Chemistry
for Life Science, Kobe Pharmaceutical University, 4-19-1, Motoyamakita-machi, Higashinada-ku, Kobe 658-8558, Japan
| | - Kohei Nakata
- Department of Organic Chemistry
for Life Science, Kobe Pharmaceutical University, 4-19-1, Motoyamakita-machi, Higashinada-ku, Kobe 658-8558, Japan
| | - Kenji Nishigaki
- Department of Organic Chemistry
for Life Science, Kobe Pharmaceutical University, 4-19-1, Motoyamakita-machi, Higashinada-ku, Kobe 658-8558, Japan
| | - Naoyuki Michioka
- Department of Organic Chemistry
for Life Science, Kobe Pharmaceutical University, 4-19-1, Motoyamakita-machi, Higashinada-ku, Kobe 658-8558, Japan
| | - Mitsuaki Karatani
- Department of Organic Chemistry
for Life Science, Kobe Pharmaceutical University, 4-19-1, Motoyamakita-machi, Higashinada-ku, Kobe 658-8558, Japan
| | - Akimori Wada
- Department of Organic Chemistry
for Life Science, Kobe Pharmaceutical University, 4-19-1, Motoyamakita-machi, Higashinada-ku, Kobe 658-8558, Japan
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Maegawa T, Fujioka H. Reaction via Pyridinium-type Salt Intermediate: Chemoselective Deprotection of Acetals in the Presence of Ketals and Nucleophilic Substitution. J SYN ORG CHEM JPN 2013. [DOI: 10.5059/yukigoseikyokaishi.71.694] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Minamitsuji Y, Kawaguchi A, Kubo O, Ueyama Y, Maegawa T, Fujioka H. A Mild and Versatile Method for the Synthesis of Alkyl Ethers from Methoxymethyl Ethers and Application to the Preparation of Sterically Crowded Ethers. Adv Synth Catal 2012. [DOI: 10.1002/adsc.201200290] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Fujioka H, Minamitsuji Y, Moriya T, Okamoto K, Kubo O, Matsushita T, Murai K. Preparation of THP‐Ester‐Derived Pyridinium‐Type Salts and their Reactions with Various Nucleophiles. Chem Asian J 2012; 7:1925-33. [DOI: 10.1002/asia.201200234] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2012] [Indexed: 11/06/2022]
Affiliation(s)
- Hiromichi Fujioka
- Graduate School of Pharmaceutical Sciences, Osaka University, 1–6 Yamada‐oka, Suita, Osaka, 565‐0871 (Japan), Fax: (+81)6‐6879‐8229
| | - Yutaka Minamitsuji
- Graduate School of Pharmaceutical Sciences, Osaka University, 1–6 Yamada‐oka, Suita, Osaka, 565‐0871 (Japan), Fax: (+81)6‐6879‐8229
| | - Takahiro Moriya
- Graduate School of Pharmaceutical Sciences, Osaka University, 1–6 Yamada‐oka, Suita, Osaka, 565‐0871 (Japan), Fax: (+81)6‐6879‐8229
| | - Kazuhisa Okamoto
- Graduate School of Pharmaceutical Sciences, Osaka University, 1–6 Yamada‐oka, Suita, Osaka, 565‐0871 (Japan), Fax: (+81)6‐6879‐8229
| | - Ozora Kubo
- Graduate School of Pharmaceutical Sciences, Osaka University, 1–6 Yamada‐oka, Suita, Osaka, 565‐0871 (Japan), Fax: (+81)6‐6879‐8229
| | - Tomoyo Matsushita
- Graduate School of Pharmaceutical Sciences, Osaka University, 1–6 Yamada‐oka, Suita, Osaka, 565‐0871 (Japan), Fax: (+81)6‐6879‐8229
| | - Kenichi Murai
- Graduate School of Pharmaceutical Sciences, Osaka University, 1–6 Yamada‐oka, Suita, Osaka, 565‐0871 (Japan), Fax: (+81)6‐6879‐8229
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Kumar KR, Satyanarayana PVV, Reddy BS. Simple and Efficient Method for Deprotection of Tetrahydropyranyl Ethers by Using Silica Supported Sodium Hydrogen Sulphate. CHINESE J CHEM 2012. [DOI: 10.1002/cjoc.201100358] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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11
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Okitsu T, Nagase K, Nishio N, Wada A. Tandem Migration–Carboalkoxylation of o-Isocyanophenyl Acetals Leading to Benzoxazoles. Org Lett 2012; 14:708-11. [DOI: 10.1021/ol203175a] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Takashi Okitsu
- Department of Organic Chemistry for Life Science, Kobe Pharmaceutical University, 4-19-1, Motoyamakita-machi, Higashinada-ku, Kobe 658-8558, Japan
| | - Kenta Nagase
- Department of Organic Chemistry for Life Science, Kobe Pharmaceutical University, 4-19-1, Motoyamakita-machi, Higashinada-ku, Kobe 658-8558, Japan
| | - Nobuhiko Nishio
- Department of Organic Chemistry for Life Science, Kobe Pharmaceutical University, 4-19-1, Motoyamakita-machi, Higashinada-ku, Kobe 658-8558, Japan
| | - Akimori Wada
- Department of Organic Chemistry for Life Science, Kobe Pharmaceutical University, 4-19-1, Motoyamakita-machi, Higashinada-ku, Kobe 658-8558, Japan
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12
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Fujioka H, Maegawa T, Koutani Y, Senami K, Yahata K. Selective Deprotection of Methylene Acetal and MOM Ether in the Presence of Ketal-Type Protective Groups: Remarkable Effect of TBSOTf. HETEROCYCLES 2012. [DOI: 10.3987/com-12-s(n)43] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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13
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Fujioka H, Yahata K, Hamada T, Kubo O, Okitsu T, Sawama Y, Ohnaka T, Maegawa T, Kita Y. Reaction of Acetals with Various Carbon Nucleophiles under Non-Acidic Conditions: CC Bond Formation via a Pyridinium-Type Salt. Chem Asian J 2011; 7:367-73. [PMID: 22162390 DOI: 10.1002/asia.201100812] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Indexed: 11/07/2022]
Affiliation(s)
- Hiromichi Fujioka
- Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamada-oka Suita, Osaka 565-0871, Japan.
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14
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Fujioka H, Minamitsuji Y, Kubo O, Senami K, Maegawa T. The reaction of acetal-type protective groups in combination with TMSOTf and 2,2′-bipyridyl; mild and chemoselective deprotection and direct conversion to other protective groups. Tetrahedron 2011. [DOI: 10.1016/j.tet.2011.02.048] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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15
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Fujioka H, Goto A, Otake K, Kubo O, Sawama Y, Maegawa T. An unusual reaction of α-alkoxyphosphonium salts with Grignard reagents under an O2 atmosphere. Chem Commun (Camb) 2011; 47:9894-6. [PMID: 21814703 DOI: 10.1039/c1cc13919c] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Affiliation(s)
- Hiromichi Fujioka
- Graduate School of Pharmaceutical Sciences, Osaka University, Suita, Osaka, Japan.
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Kubo O, Yahata K, Maegawa T, Fujioka H. 2,5-cis-2,3,5-Trisubstituted tetrahydrofurans from the diastereomixture of 2,4-disubstituted 1,3-dioxepins via stereomutation. Chem Commun (Camb) 2011; 47:9197-9. [DOI: 10.1039/c1cc12934a] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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17
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Maegawa T, Otake K, Goto A, Fujioka H. Direct conversion of acetals to esters with high regioselectivity via O,P-acetals. Org Biomol Chem 2011; 9:5648-51. [DOI: 10.1039/c1ob05687e] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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18
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Fujioka H, Goto A, Otake K, Kubo O, Yahata K, Sawama Y, Maegawa T. Remarkable effect of phosphine on the reactivity of O,P-acetal—efficient substitution reaction of O,P-acetal. Chem Commun (Camb) 2010; 46:3976-8. [PMID: 20449525 DOI: 10.1039/c0cc00170h] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Affiliation(s)
- Hiromichi Fujioka
- Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamada-oka, Suita, Osaka 565-0871, Japan.
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Fujioka H, Senami K, Kubo O, Yahata K, Minamitsuji Y, Maegawa T. Mild Deprotection of Methylene Acetals in Combination with Trimethylsilyl Triflate-2,2'-Bipyridyl. Chem Pharm Bull (Tokyo) 2010; 58:426-8. [DOI: 10.1248/cpb.58.426] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
| | - Kento Senami
- Graduate School of Pharmaceutical Sciences, Osaka University
| | - Ozora Kubo
- Graduate School of Pharmaceutical Sciences, Osaka University
| | - Kenzo Yahata
- Graduate School of Pharmaceutical Sciences, Osaka University
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Fujioka H, Senami K, Kubo O, Yahata K, Minamitsuji Y, Maegawa T. Novel regiocontrolled protection of 1,2- and 1,3-diols via mild cleavage of methylene acetals. Org Lett 2009; 11:5138-41. [PMID: 19821584 DOI: 10.1021/ol902088b] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The regiocontrolled protection of unsymmetrical 1,2- and 1,3-diols has been developed. Different types of protected diols are available from the methylene acetal in a one-pot procedure. Highly regioselective protection of diols with a silyl group at the less hindered hydroxy group as well as with a MOM group at the more hindered one were achieved. The reaction conditions are mild without affecting other functional groups including acid-labile function.
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Affiliation(s)
- Hiromichi Fujioka
- Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamada-oka Suita, Osaka 565-0871, Japan.
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21
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Herndon JW. The chemistry of the carbon-transition metal double and triple bond: Annual survey covering the Year 2007. Coord Chem Rev 2009. [DOI: 10.1016/j.ccr.2008.12.013] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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22
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Fujioka H, Kita Y, Kubo O, Okamoto K, Senami K, Okitsu T, Sawama Y. Mild and Efficient Deprotection of Acetal-Type Protecting Groups of Hydroxyl Functions by Triethylsilyl Triflate — 2,4,6-Collidine Combination. HETEROCYCLES 2009. [DOI: 10.3987/com-08-s(f)88] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Fujioka H, Kita Y, Kubo O, Senami K, Okamoto K, Okitsu T. Organic Chemistry Using Weakly Electrophilic Salts: The Reaction with Nitrogen Nucleophiles. HETEROCYCLES 2009. [DOI: 10.3987/com-08-s(d)69] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Fujioka H, Kubo O, Senami K, Minamitsuji Y, Maegawa T. Remarkable effect of 2,2′-bipyridyl: mild and highly chemoselective deprotection of methoxymethyl (MOM) ethers in combination with TMSOTf (TESOTf)–2,2′-bipyridyl. Chem Commun (Camb) 2009:4429-31. [DOI: 10.1039/b907910f] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Okitsu T, Nakazawa D, Taniguchi R, Wada A. Iodocyclization of Ethoxyethyl Ethers to Alkynes: A Broadly Applicable Synthesis of 3-Iodobenzo[b]furans. Org Lett 2008; 10:4967-70. [DOI: 10.1021/ol8020463] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Takashi Okitsu
- Department of Organic Chemistry for Life Science, Kobe Pharmaceutical University, 4-19-1, Motoyamakita-machi, Higashinada-ku, Kobe 658-8558, Japan
| | - Daisuke Nakazawa
- Department of Organic Chemistry for Life Science, Kobe Pharmaceutical University, 4-19-1, Motoyamakita-machi, Higashinada-ku, Kobe 658-8558, Japan
| | - Rie Taniguchi
- Department of Organic Chemistry for Life Science, Kobe Pharmaceutical University, 4-19-1, Motoyamakita-machi, Higashinada-ku, Kobe 658-8558, Japan
| | - Akimori Wada
- Department of Organic Chemistry for Life Science, Kobe Pharmaceutical University, 4-19-1, Motoyamakita-machi, Higashinada-ku, Kobe 658-8558, Japan
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Fujioka H, Okitsu T, Ohnaka T, Li R, Kubo O, Okamoto K, Sawama Y, Kita Y. Organic Chemistry Using Weakly Electrophilic Salts: Efficient Formation of O,O-Mixed, O,S- and N,O-Acetals. J Org Chem 2007; 72:7898-902. [PMID: 17887700 DOI: 10.1021/jo071187g] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A mild and efficient method for the preparation of O,O-mixed, O,S- and N,O-acetals from symmetrical O,O-acetals has been developed. Thus, the treatment of symmetrical O,O-acetals with TESOTf and 2,4,6-collidine formed weakly electrophilic collidinium salts. The addition of nucleophiles, such as an alcohol, lithium thioxide, and sodium azide, to the salts afforded the corresponding O,O-mixed, O,S- and N,O-acetals in good yields. The reaction proceeded under weakly basic conditions. No overreaction then occurred and many acid-labile functional groups could remain intact.
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Affiliation(s)
- Hiromichi Fujioka
- Graduate School of Pharmaceutical Sciences, Osaka University, 1-6, Yamada-oka, Suita, Osaka 565-0871, Japan.
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