- Enantioselective Synthesis of Pyrrolizin-1-ones via Lewis Base Catalyzed N-Allylation of N-Silyl Pyrrole Latent Nucleophiles
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Pyrrolizidine alkaloids and their derivatives often feature interesting biological activities. A class of substituted 2,3-dihydro-1H-pyrrolizin-1-one derivatives has been explored as a potential treatment for Alzheimer's disease, but enantioselective synthesis of these molecules is still elusive. We report that enantioselective N-allylation of N-silyl pyrrole latent nucleophiles with allylic fluorides followed by hydrogenation and diastereoselective Friedel-Crafts cyclization constitute an efficient synthetic route to access enantioenriched substituted 2,3-dihydro-1H-pyrrolizin-1-ones.
- Lange, Markus,Zi, You,Vilotijevic, Ivan
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- Latent Nucleophiles in Lewis Base Catalyzed Enantioselective N-Allylations of N-Heterocycles
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Latent nucleophiles are compounds that are themselves not nucleophilic but can produce a strong nucleophile when activated. Such nucleophiles can expand the scope of Lewis base catalyzed reactions. As a proof of concept, we report that N-silyl pyrroles, i
- Zi, You,Lange, Markus,Schultz, Constanze,Vilotijevic, Ivan
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supporting information
p. 10727 - 10731
(2019/07/09)
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- Electron transfer-induced reduction of organic halides with amines
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Reduction of a variety of organo halides was examined by using amines as a sacrificial hydrogen source. UV light-induced reduction of vinyl and aryl halides with triethylamine proceeded smoothly to give the corresponding reduced products. High temperature heating also caused the reduction and DABCO (1,4-diazabicyclo[2.2.2]octane) also served as a good reducing reagent.
- Fukuyama, Takahide,Fujita, Yuki,Miyoshi, Hayato,Ryu, Ilhyong,Kao, Shih-Chieh,Wu, Yen-Ku
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supporting information
p. 5582 - 5585
(2018/06/04)
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- Iridium- and Rhodium-Catalyzed Directed C-H Heteroarylation of Benzaldehydes with Benziodoxolone Hypervalent Iodine Reagents
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The C-H heteroarylation of benzaldehydes with indoles and pyrroles was realized using the benziodoxolone hypervalent iodine reagents indole- and pyrroleBX. Functionalization of the aldehyde C-H bond using either an o-hydroxy or amino directing group and catalyzed by an iridium or a rhodium complex allowed the synthesis of salicyloylindoles and (2-sulfonamino)benzoylindoles, respectively, with good to excellent yields (74-98%). This new transformation could be carried out under mild conditions (rt to 40 °C) and tolerated a broad range of functionalities, such as ethers, halogens, carbonyls, or nitro groups.
- Grenet, Erwann,Waser, Jér?me
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supporting information
p. 1473 - 1476
(2018/03/09)
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- Rhodium-catalyzed C–H functionalization of heteroarenes using indoleBX hypervalent iodine reagents
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The C–H indolation of heteroarenes was realized using the benziodoxolone hypervalent iodine reagents indoleBXs. Functionalization of the C–H bond in bipyridinones and quinoline N-oxides catalyzed by a rhodium complex allowed to incorporate indole rings into aza-heteroaromatic compounds. These new transformations displayed complete regioselectivity for the C-6 position of bipyridinones and the C-8 position of quinoline N-oxides and tolerated a broad range of functionalities, such as halogens, ethers, or trifluoromethyl groups.
- Grenet, Erwann,Das, Ashis,Caramenti, Paola,Waser, Jér?me
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supporting information
p. 1208 - 1214
(2018/06/04)
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- Lewis Acid Catalyzed Enantioselective Desymmetrization of Donor–Acceptor meso-Diaminocyclopropanes
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The first Lewis acid catalyzed enantioselective ring-opening desymmetrization of a donor–acceptor meso-diaminocyclopropane is reported. The copper(II)-catalyzed Friedel–Crafts alkylation of indoles and one pyrrole with an unprecedented meso-diaminocyclopropane delivered enantioenriched, diastereomerically pure urea products, which are structurally related to natural and synthetic bioactive compounds. The development of a new ligand through the investigation of an underexplored subclass of bis(oxazoline) ligands was essential for achieving high enantioselectivities.
- Perrotta, Daniele,Wang, Ming-Ming,Waser, Jér?me
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supporting information
p. 5120 - 5123
(2018/03/27)
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- Indole- and Pyrrole-BX: Bench-Stable Hypervalent Iodine Reagents for Heterocycle Umpolung
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The one-step synthesis of the bench-stable hypervalent iodine reagents IndoleBX and PyrroleBX using mild Lewis acid catalyzed conditions is reported. The new reagents are stable up to 150 °C and were applied in the C?H arylation of unactivated arenes using either rhodium or ruthenium catalysts. A broad range of heterocyclic systems of high interest for synthetic and medicinal chemistry was accessed in high yields. The developed C?H functionalization could not be achieved using reported reagents or methods, highlighting the unique reactivity of Indole- and Pyrrole-BX.
- Caramenti, Paola,Nicolai, Stefano,Waser, Jerome
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supporting information
p. 14702 - 14706
(2017/09/11)
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- On water phosphine-free palladium-catalyzed room temperature C-H arylation of indoles
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Get on top of your chemistry! An "on water", palladium-catalyzed, phosphine-free direct C-H arylation of indoles, with iodoarenes at 25-30°C, is disclosed (see scheme; TBDMS=N-tert-butyldimethylsilyl ether; SEM=N-2-(trimethylsilyl)ethoxymethyl; Bn=benzyl, Piv=pivabyl). The mildness of the reaction conditions permits the tolerance of a variety of N1-protected indoles.
- Islam, Saidul,Larrosa, Igor
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supporting information
p. 15093 - 15096
(2013/11/06)
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- 3-Indolylphosphines as ligand for palladium in Suzuki-Miyaura coupling reaction of chloroarenes: Substituent effects
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The ligand 1,3-bis(diphenylphosphino)-1H-indole, L1 with palladium promotes Suzuki-Miyaura coupling reaction of chloroarenes and benzyl chlorides with arylboronic acids. Structural modification of L1 established that the phosphine group at C-3 position of indole was crucial to catalysis and its efficacy depended on the nature of the N-substituent. 31P chemical shift values of the substituted indolylphosphines appear to show a correlation with observed trend in catalytic efficiency.
- Saha, Debajyoti,Ghosh, Raju,Sarkar, Amitabha
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p. 3951 - 3960
(2013/06/27)
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- Asymmetric synthesis of indole homo-Michael adducts via dynamic kinetic Friedel-Crafts alkylation with cyclopropanes
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An enantioconvergent Friedel-Crafts alkylation of indoles with donor-acceptor cyclopropanes is described. The reaction is catalyzed by pybox?MgI2 and proceeds via a type I dynamic kinetic asymmetric transformation (DyKAT).
- Wales, Steven M.,Walker, Morgan M.,Johnson, Jeffrey S.
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supporting information
p. 2558 - 2561
(2013/07/11)
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- Synthesis and structure activity relationship of rigidized indolyl pyrrolidine derivatives as 5-HT6 receptor ligands
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A novel series of rigidized indolyl pyrrolidine derivatives have been designed by constraining the tryptamine nitrogen through a and b carbons. All the synthesized derivatives have shown moderate affinities at 5-HT6R when tested in in vitro binding assay.
- Nirogi, Ramakrishna,Dwarampudi, Adireddy,Bhatta, Venugopalarao,Kota, Laxman,Dubey
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p. 9293 - 9298
(2013/11/19)
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- Zinc-catalyzed dehydrogenative N-silylation of indoles with hydrosilanes
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Zinc catalysis: Zinc triflate in a nitrile solvent behaved as an effective catalyst for dehydrogenative N-silylation with a variety of indoles and hydrosilanes (see scheme). The addition of pyridine greatly accelerated the N-silylation reaction to produce N-silylindoles exclusively in high to excellent yields. Copyright
- Tsuchimoto, Teruhisa,Iketani, Yoshihiko,Sekine, Masaru
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supporting information; experimental part
p. 9500 - 9504
(2012/09/21)
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- Rhodium acetate/base-catalyzed N-silylation of indole derivatives with hydrosilanes
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In the presence of Rh2(OAc)4 (OAc = acetate) and TBA2WO4 (TBA = tetra-n-butylammonium), the N-silylation of indole derivatives with hydrosilanes efficiently proceeded to give the corresponding N-silylated indole
- Itagaki, Shintaro,Kamata, Keigo,Yamaguchi, Kazuya,Mizuno, Noritaka
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supporting information; experimental part
p. 9269 - 9271
(2012/09/22)
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- Synthesis of indole and biindolyl triflones: Trifluoromethanesulfonylation of indoles with Tf2O/TTBP (2,4,6-tri- tert -butylpyridine) system
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A convenient synthesis of indole triflones is reported. N-Alkyl, aryl and N-H indole triflones were obtained in 82-96% yields by the Tf2O/TTBP System. Biindolyl triflones were accessed in 51-81% yields for the first time by simple treatment of the resulting indole triflones with a base and without any use of organometallic chemistry. An environmentally friendly solvent, Solkane 365/227, can be substituted for this process without any loss of efficiency.
- Xu, Xiu-Hua,Liu, Guo-Kai,Azuma, Ayaka,Tokunaga, Etsuko,Shibata, Norio
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supporting information; experimental part
p. 4854 - 4857
(2011/11/06)
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- NOVEL INDOLIC DERIVATIVES, THEIR PREPARATION PROCESSES AND THEIR USES IN PARTICULAR AS ANTIBACTERIALS
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The invention relates to the use of at least one compound of the formula (I), in which R and R3 are particularly a hydrogen atom, R1 is particularly a hydrogen atom or a methyl, ethyl or isobutyl mi group, R4, R5, R6 and R7 are independently a hydrogen atony, an alkoxyl group with 1 to 7 carbon atoms or a halogen atom, R2 is a hydrogen atom, an O? group or an OH group, B is an N-GP1 or NRc, group, GP1 being a Boc or Cbz group, and Rc is a hydrogen atom or a methyl or t-butyl group, for preparing a drug for treating conditions associated with bacterial infections, in particular for treating bacterial diseases.
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- Chiral phosphoric acid-catalyzed enantioselective aza-Friedel-Crafts reaction of indoles
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A highly enantioselective 1,2-aza-Friedel-Crafts reaction of N-tert-butyldimethylsilylindole with N-tert-butoxycarbonyl aromatic imines is demonstrated using a BINOL-derived monophosphoric acid catalyst. The present approach provides efficient access to 3-indolylmethaneamines with aryl substituents in excellent enantioselectivities (up to 98% ee). An inversion in the sense of enantioselection was found between monophosphoric acid catalysts bearing different substituents introduced at the 3,3′-position of binaphthyl backbone. We also calculated the three-dimensional structure of the monophosphoric acid catalysts to speculate on the inversion of the stereochemical outcome.
- Terada, Masahiro,Yokoyama, Shigeko,Sorimachi, Keiichi,Uraguchi, Daisuke
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p. 1863 - 1867
(2008/09/17)
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- Synthesis of (3-indolyl)heteroaromatics by Suzuki-Miyaura coupling and their inhibitory activity in lipid peroxidation
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A variety of (3-indolyl)heteroaromatic compounds were synthesized by Suzuki-Miyaura coupling of 3-indolylboronic acid and halogenated heteroaromatics. 2-(3-Indolyl)thiophene showed potent inhibitory activity against lipid peroxidation by rat liver microsome.
- Nishida, Atsushi,Miyashita, Naoki,Fuwa, Mihoko,Nakagawa, Masako
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p. 473 - 476
(2007/10/03)
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- Synthesis of 3-[(1-aryl)aminomethyl]indoles
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We report the novel synthesis of various highly functionalized 3-arylaminomethyl indoles. This synthetic approach makes use of the directing ability of a bulky tertbutyldimethylsilyl-protecting group, which directs the condensation of an array of aromatic tosylaldimines specifically into the 3-position of the indole nucleus. The reactions, which occur under relatively mild conditions, afford the desired products in moderate yields. Prior to selective cleavage of the protecting group, the functionalized protected indoles also serve as attractive substrates for many future organic transformations.
- Wynne, James H.,Stalick, Wayne M.
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p. 5850 - 5853
(2007/10/03)
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- Efficient asymmetric synthesis of biologically important tryptophan analogues via a palladium-mediated heteroannulation reaction
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A novel and concise synthesis of optically active tryptophan derivatives was developed via a palladium-catalyzed heteroannulation reaction of substituted o-iodoanilines with an internal alkyne. The required internal alkyne 14a or 25 was prepared in greater than 96% de via alkylation of the Schoellkopf chiral auxiliary 19 employing diphenyl phosphate as the leaving group. The Schoellkopf chiral auxiliary was chosen here for the preparation of L-tryptophans would be available from D-valine while the D-isomers required for natural product total synthesis would originate from the inexpensive L-valine (300-g scale). Applications of the palladium-catalyzed heteroannulation reaction were extended to the first asymmetric synthesis of L-isotryptophan 38 and L-benz[f]tryptophan 39. More importantly, the optically pure 6-methoxy-D-tryptophan 62 was prepared by this protocol on a large scale (>300 g). This should permit entry into many ring-A oxygenated indole alkaloids when coupled with the asymmetric Pictet-Spengler reaction. In addition, an improved total synthesis of tryprostatin A (9a) was accomplished in 43% overall yield employing this palladium-mediated process.
- Ma,Liu,Li,Flippen-Anderson,Yu,Cook
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p. 4525 - 4542
(2007/10/03)
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- Reactions of a nitrodienamine with 1-protected indolyllithium
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Reactions of a nitrodienamine (1) with indolyllithiums prepared from 1-protected indole derivatives were investigated.
- Koike, Takeshi,Shinohara, Yoshifumi,Tobinaga, Seisho,Takeuchi, Naoki
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p. 2701 - 2708
(2007/10/03)
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- Preparation and Reactions of 1-(tert-Butyldimethylsilyl)-3-lithioindole. Regioselective Synthesis of 3-Substituted Indoles
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1-(tert-Butyldimethylsilyl)-3-lithioindole (2) is prepared by metalation of the corresponding 3-bromo derivative 1 and efficiently reacts with electrophiles to give 3-substituted indoles 3 and 4.
- Amat, Mercedes,Hadida, Sabine,Sathyanarayana, Swargam,Bosch, Joan
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- NOVEL TRICHLOROACETYL BASED SILYLATIONS: SIMPLE METHODS FOR t-BUTYLDIMETHYLSILYLATIONS AND FOR THE PROTECTION OF AMINO GROUPS.
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A new reagent for t-butyldimethylsilylation has been developed and the known trimethylsilyl trichloroacetate (1) has been shown to be of use for N-silylating amines.
- Galan, Adam A.,Lee, Thomas V.,Chapleo, Christopher B.
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p. 4995 - 4998
(2007/10/02)
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- Studies in the Protection of Pyrrole and Indole Derivatives
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Treatment of pyrrole (1a), 2,5-dimethylpyrrole (1b), indole (3a), 2-methylindole (3b), 3-methylindole (3c), 2,3-dimethylindole (3d), 1,2,3,4-tetrahydro-9H-carbazole (5a), 5,6,7,8,9,10-hexahydrocycloheptindole (5b), and 6,7,8,9,10,11-hexahydro-5H-cyclo-octindole (5c) with sodium hydride in tetrahydrofuran, followed by phenyl t-butyl carbonate (8) gives the corresponding N-t-butoxycarbonyl (t-BOC) derivatives in satisfactory yields.By using chlorodimethyl-t-butylsilane instead of (8), N-dimethyl-t-butylsilyl derivatives are obtained, also in satisfactory yields.The use of the 2-(trimethylsilyl)ethoxycarbonyl (TEOC) group for the N-protection of the indole system, and the pivaloyloxymethyl (POM) group for the N-protection of the pyrrole and indole systems is also described.
- Dhanak, Dashyant,Reese, Colin B.
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p. 2181 - 2186
(2007/10/02)
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