- Enantioselective Synthesis of 3a-Amino-Pyrroloindolines by Copper-Catalyzed Direct Asymmetric Dearomative Amination of Tryptamines
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A direct asymmetric dearomative amination of tryptamines with O-(2,4-dinitrophenyl)hydroxylamine (DPH) was achieved using CuBr-bisoxazoline complex as a catalyst, affording 3a-amino-pyrroloindolines in good to excellent enantioselectivity under mild reaction conditions. Furthermore, the synthetic value of this method was demonstrated in the total synthesis of (-)-psychotriasine in a highly concise manner. A direct asymmetric dearomative amination of tryptamines with O-(2,4-dinitrophenyl)hydroxylamine (DPH) was achieved using CuBr-bisoxazoline complex as a catalyst, affording 3a-amino-pyrroloindolines in good enantioselectivity under mild reaction conditions. The synthetic value of this method was demonstrated in the total synthesis of (-)-psychotriasine in a highly concise manner.
- Liu, Chuan,Yi, Ji-Cheng,Zheng, Zhong-Bo,Tang, Yong,Dai, Li-Xin,You, Shu-Li
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- Fenton chemistry enables the catalytic oxidative rearrangement of indoles using hydrogen peroxide
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Oxidative rearrangement of indoles is an important transformation to yield 2-oxindoles and spirooxindoles, which are present in many pharmaceutical agents and bioactive natural products. Previous oxidation methods show either broad applicability or greenness but rarely achieve both. Reported is the discovery of Fenton chemistry-enabled green catalytic oxidative rearrangement of indoles, which has wide substrate scope (42 examples) and greenness (water as the only stoichiometric byproduct) at the same time. Detailed mechanistic studies revealed that the Fenton chemistry generated hydroxyl radicals that further oxidize bromide to reactive brominating species (RBS: bromine or hypobromous acid). Thisin situgenerated RBS is the real catalyst for the oxidative rearrangement. Importantly, the RBS is generated under neutral conditions, which addresses a long-lasting problem of many haloperoxidase mimics that require a strong acid for the oxidation of bromide with hydrogen peroxide. It is expected that this new catalytic Fenton-halide system will find wide applications in organic synthesis.
- Zhao, Guodong,Liang, Lixin,Wang, Eryu,Lou, Shaoyan,Qi, Rui,Tong, Rongbiao
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supporting information
p. 2300 - 2307
(2021/04/12)
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- Structural Revision of Pseudocerosine and Validation of a Biosynthetic Proposal for E-ring Formation in Pyridoacridine Alkaloids
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Pseudocerosine is the pigment responsible for the bright blue color of the rim on the marine flatworm Pseudoceros indicus. Compelling evidence is provided herein that pseudocerosine is actually a pyridoacridine, not an azepinoindole as initially proposed. This study also validates a biosynthesis proposal for E-ring formation in this revered class of alkaloids, and pseudocerosine (along with its intermediates described herein) is a new branch on the pyridoacridine family tree.
- Kim, Se Hun,S?hnel, Tilo,Sperry, Jonathan
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supporting information
p. 3495 - 3498
(2020/04/21)
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- An environmentally friendly protocol for oxidative halocyclization of tryptamine and tryptophol derivatives
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An environmentally friendly and efficient protocol (KX/oxone) for oxidative halocyclization of tryptamine/tryptophol derivatives was developed and demonstrated with 28 examples and concise total synthesis of cyclotryptamine alkaloid protubonines A and B. The distinct advantage of this protocol over all previous methods is that no organic byproduct is generated from a halogenating agent or oxidant, thus greatly reducing the environmental impact of halocyclization and facilitating the post-reaction purification.
- Xu, Jun,Tong, Rongbiao
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p. 2952 - 2956
(2017/07/24)
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- Lewis Acid Catalyzed Displacement of Trichloroacetimidates in the Synthesis of Functionalized Pyrroloindolines
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The pyrroloindoline core is found in many natural products. These structures often differ at the C3a position, which may be substituted with an oxygen, nitrogen, or sp3- or sp2-hybridized carbon. Utilizing a trichloroacetimidate leaving group, a diversity-oriented approach to these structures has been developed. The trichloroacetimidate intermediate allows for the rapid incorporation of anilines, alcohols, thiols, and carbon nucleophiles. This method was applied in the synthesis of arundinine and a formal synthesis of psychotriasine.
- Adhikari, Arijit A.,Chisholm, John D.
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supporting information
p. 4100 - 4103
(2016/08/30)
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- Synthesis of pyrroloindolines and furoindolines via cascade dearomatization of indole derivatives with carbenium ion
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A highly efficient intermolecular cascade dearomatization of substituted indoles with benzodithiolylium tetrafluoroborate has been developed. This reaction provides a novel strategy to synthesise C3 methyl-substituted pyrroloindolines and furoindolines under mild reaction conditions, the utility of which has been demonstrated by the synthesis of esermethol and physovenine in a highly concise manner.
- Liu, Chuan,Yin, Qin,Dai, Li-Xin,You, Shu-Li
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supporting information
p. 5971 - 5974
(2015/03/30)
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- The ideal synthetic method aimed at the leads for an α2-blocker, an inhibitor of blood platelet aggregation, and an anti-osteoporosis agent
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According to the definition of the ideal synthetic method, an example aimed at the leads for an α2 blocker, an inhibitor of platelet aggregation, and an anti-osteoporosis agent is established starting from tryptamine. The originality rate, the intellectual property, and the application potential factors of the method are 71, 54, and 100, respectively. The method employs only conventional reagents and reaction conditions without using any protecting groups.{A figure is presented}.
- Somei, Masanori,Iwaki, Takako,Yamada, Fumio,Tanaka, Yoshio,Shigenobu, Koki,Koike, Katsuo,Suzuki, Nobuo,Hattori, Atsuhiko
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p. 1565 - 1569
(2007/10/03)
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- Syntheses of melatonin and its derivatives
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Two simple synthetic methods for melatonin are newly developed from tryptamine through intermediates, which are promising lead compounds for drug developing research. Novel chemical reactivities of melatonin in its bromination, lithiation, and acylation are also reported.
- Somei, Masanori,Fukui, Yoshikazu,Hasegawa, Masakazu,Oshikiri, Naoki,Hayashi, Toshikatsu
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p. 1725 - 1736
(2007/10/03)
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- Preparations of melatonin and 1-hydroxymelatonin, and its novel nucleophilic dimerization to (±)-3a,3a'-bispyrrolo[2,3-b]indoles
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A unique synthetic method for melatonin was established through biologically promising synthetic intermediates. 1-Hydroxymelatonin was prepared as crystals for the first time. It reacted with 85% formic acid to give (±)-3a,3a'-bispyrrolo[2,3-b]indole compound, whose structure was unequivocally determined by X-Ray crystallographic analysis.
- Somei, Masanori,Oshikiri, Naoki,Hasegawa, Masakazu,Yamada, Fumio
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p. 1237 - 1242
(2007/10/03)
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- Total syntheses and anticholinesterase activities of (3aS)-N(8)- norphysostigmine, (3aS)-N(8)-norphenserine, their antipodal isomers, and other N(8)-substituted analogues
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N(8)-Benzylesermethole (6) was prepared from 5-methoxytryptamine (1) in five steps. Resolution of compound 6 by dibenzoyl- and ditoluyltartaric acid provided enantiomers (-)- and (+)7. After demethylation, reaction with isocyanates and catalytic debenzyla
- Yu, Qian-Sheng,Pei, Xue-Feng,Holloway, Harold W.,Greig, Nigel H.,Brossi, Arnold
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p. 2895 - 2901
(2007/10/03)
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