120-72-9Relevant articles and documents
One-pot tandem synthesis of 2,3-unsubstituted indoles, an improved Leimgruber-Batchoindole synthesis
Chen, Jinchun,Zhang, Zhikai,Liu, Sujing,Yang, Cuiyun,Xia, Chuanhai
, p. 4672 - 4675 (2014)
A concise, fast and efficient one-pot methodology has been developed for preparing 2,3-unsubstituted indoles from 2-nitrotoluenes and dimethylformamide dimethyl acetal. Compared with the classical Leimgruber-Batcho reaction, such a one-pot process simplified the operation procedures, generated less by-products and chemical residues, and resulted in higher overall yields in a shorter reaction time.
A BN Aromatic Ring Strategy for Tunable Hydroxy Content in Polystyrene
van de Wouw, Heidi L.,Lee, Jae Young,Awuyah, Elorm C.,Klausen, Rebekka S.
, p. 1673 - 1677 (2018)
BN 2-vinylnaphthalene, a BN aromatic vinyl monomer, is copolymerized with styrene under free radical conditions. Oxidation yields styrene–vinyl alcohol (SVA) statistical copolymers with tunable hydroxy group content. Comprehensive spectroscopic investigation provides proof of structure. Physical properties that vary systematically with hydroxy content include solubility and glass transition temperature. BN aromatic polymers represent a platform for the preparation of diverse functional polymeric architectures via the remarkable reaction chemistry of C?B bonds.
Properties of tryptophan indole-lyase from a piezophilic bacterium, Photobacterium profundum SS9
Phillips, Robert S.,Ghaffari, Rashin,Dinh, Peter,Lima, Santiago,Bartlett, Douglas
, p. 35 - 41 (2011)
Tryptophan indole-lyase (Trpase), PBPRA2532, from Photobacterium profundum SS9, a piezophilic marine bacterium, has been cloned, expressed in Escherichia coli, and purified. The P. profundum Trpase (PpTrpase) exhibits similar substrate specificity as the enzyme from E. coli (EcTrpase). PpTrpase has an optimum temperature for activity at about 30 °C, compared with 53 °C for EcTrpase, and loses activity rapidly (t1/2 ～ 30 min) when incubated at 50 °C, while EcTrpase is stable up to 65 °C. PpTrpase retains complete activity when incubated more than 3 h at 0 °C, while EcTrpase has only about 20% remaining activity. Under hydrostatic pressure, PpTrpase remains fully active up to 100 MPa (986 atm), while EcTrpase exhibits only about 10% activity at 100 MPa. PpTrpase forms external aldimine and quinonoid intermediates in stopped-flow experiments with l-Trp, S-Et-l-Cys, S-benzyl-l-Cys, oxindolyl-l-Ala, l-Ala and l-Met, similar to EcTrpase. However, with l-Trp a gem-diamine is observed that decays to a quinonoid complex. An aminoacrylate is observed with l-Trp in the presence of benzimidazole, as was seen previously with EcTrpase [28] but not with S-Et-l-Cys. The results show that PpTrpase is adapted for optimal activity in the low temperature, high pressure marine environment.
Origin of Stability and Inhibition of Cooperative Alkyne Hydrofunctionalization Catalysts
Chapple, Devon E.,Boyle, Paul D.,Blacquiere, Johanna M.
, p. 3789 - 3800 (2021)
New entries to the [Ru(Cp/Cp*)(PR2NR′2)(MeCN)]PF6 catalyst family were synthesized, including a Cp complex (R = Cy; R′ = Ph) and two Cp* complexes (R = Cy, Ph; R′ = Ph). These and other derivatives were used for the intramolecular hydroamination of 2-ethynylaniline to elucidate trends in catalytic lifetime and rate. The readily accessible [Ru(Cp)(PCy2NPh2)(MeCN)]PF6 derivative showed comparable lifetime to [Ru(Cp)(Pt?Bu2NPh2)(MeCN)]PF6, the previous optimal catalyst. Donor-free ‘active’ catalysts, [Ru(Cp/Cp*)(PCy2NPh2)]PF6, were prepared and their thermal stability was assessed. The relatively high stability of the Cp derivative was explained by the capacity of the PCy2NPh2 ligand to coordinate in a κ3-(P,P,Ar) mode, which protects the low-coordinate species. This coordination mode is inaccessible with the Cp* derivative. Additionally, [Ru(Cp*)(PCy2NPh2)]PF6 readily activated the C?Cl bond of the solvent dichloromethane. Variable time normalization analysis (VTNA) revealed that the indole product inhibited the catalyst [Ru(Cp)(PCy2NPh2)(MeCN)]PF6, which slowed catalytic rates.
back-to-Front Indole Synthesis Using Silver(I) Catalysis: Unexpected C-3 Pyrrole Activation Mode Supported by DFT
Clarke, Aimee K.,Lynam, Jason M.,Taylor, Richard J. K.,Unsworth, William P.
, p. 6844 - 6850 (2018)
An efficient silver(I)-catalyzed method is reported for the synthesis of substituted indoles, most notably 5-hydroxy-derivatives, via π-acidic alkyne activation. Most methods for the preparation of indoles involve annulation of a benzene precursor, but the method reported herein is unusual in that pyrrole precursors are used. Density Functional Theory (DFT) studies suggest that these reactions proceed via initial activation of the pyrrole C-3 position before undergoing subsequent rearrangement, contradicting the conventional wisdom that pyrroles are more nucleophilic through C-2.
Group VI metal-promoted endo-azacyclizations via alkyne-derived metal vinylidene carbenes
McDonald, Frank E.,Chatterjee, Arnab K.
, p. 7687 - 7690 (1997)
The molybdenum-promoted cycloisomerization of terminal alkynes tethered to nitrogen nucleophiles is described. Reaction of N-carbamoyl alkynylamines with (Et3N)Mo(CO)5 affords cyclic enecarbamates. Similarly, cyclization of 2-ethynylaniline gives the isomeric indole heterocycle, although N-3- butynylaniline affords the cyclic metal azacarbene product.
Ultrathin Amorphous/Crystalline Heterophase Rh and Rh Alloy Nanosheets as Tandem Catalysts for Direct Indole Synthesis
Ge, Jingjie,Yin, Peiqun,Chen, Ye,Cheng, Hongfei,Liu, Jiawei,Chen, Bo,Tan, Chaoliang,Yin, Peng-Fei,Zheng, Hong-Xing,Li, Qiang-Qiang,Chen, Shuangming,Xu, Wenjie,Wang, Xiaoqian,Wu, Geng,Sun, Rongbo,Shan, Xiang-Huan,Hong, Xun,Zhang, Hua
, (2021)
Heterogeneous noble-metal-based catalysis plays an essential role in the production of fine chemicals. Rh-based catalysts are one of the most active candidates for indole synthesis. However, it is still highly desired to develop heterogeneous Rh-based catalysts with high activity and selectivity. In this work, a general, facile wet-chemical method is reported to synthesize ultrathin amorphous/crystalline heterophase Rh and Rh-based bimetallic alloy nanosheets (NSs), including RhCu, RhZn, and RhRu. Impressively, the amorphous/crystalline heterophase Rh NSs exhibit enhanced catalytic activity toward the direct synthesis of indole compared to the crystalline counterpart. Importantly, the obtained amorphous/crystalline heterophase RhCu alloy NSs can further enhance the selectivity to indole of >99.9% and the conversion is 100%. This work demonstrates the importance of phase engineering and metal alloying in the rational design and synthesis of tandem heterogeneous catalysts toward fine chemical synthesis.
Ruthenium-catalyzed intramolecular hydroamination of aminoalkynes
Kondo, Teruyuki,Okada, Takumi,Suzuki, Toshiaki,Mitsudo, Take-Aki
, p. 149 - 154 (2001)
Low-valent ruthenium complexes with a π-acidic ligand, such as Ru(η6-cot)(dmfm)2 [cot=1,3,5-cyclooctatriene, dmfm=dimethyl fumarate] and Ru3(CO)12, showed high catalytic activity for the intramolecular hydroamination of aminoalkynes. The reaction is highly regioselective, in which a nitrogen atom is selectively attached to an internal carbon of alkynes to give five-, six-, and seven-membered nitrogen heterocycles as well as indoles in good to high yields.
A Reusable MOF-Supported Single-Site Zinc(II) Catalyst for Efficient Intramolecular Hydroamination of o-Alkynylanilines
Li, Beibei,Ju, Zhanfeng,Zhou, Mi,Su, Kongzhao,Yuan, Daqiang
, p. 7687 - 7691 (2019)
The exploitation of new and active earth-abundant metal catalysts is critical for sustainable chemical production. Herein, we demonstrate the design of highly efficient, robust, and reusable ZnII-bipyridine-based metal–organic framework (MOF) catalysts for the intramolecular hydroamination of o-alkynylanilines to indoles. Under similar conditions homogeneous catalytic systems mainly provide hydrolysate. Our results prove that MOFs support unique internal environments that can affect the direction of chemical reactions. The ZnII-catalyzed hydroamination reaction can be conducted without additional ligands, base, or acid, and is thus a very clean reaction system with regard to its environmental impact.
Protonated carbonic acid and reactive intermediates in the acidic decarboxylation of indolecarboxylic acids
Vandersteen, Adelle A.,Mundle, Scott O.C.,Kluger, Ronald
, p. 6505 - 6509 (2012)
Elucidation of the mechanism for decarboxylation of indolecarboxylic acids over a wide range of solution acidity reveals the importance of protonated carbonic acid (PCA) as a reaction intermediate. In concentrated acid, the initial addition of water to the carboxyl group of the indolecarboxylic acid leads to a hydrated species that is capable of releasing PCA upon rate-determining carbon-carbon bond cleavage. The overall process is catalytic in water and acid, implicating PCA as a potential carboxylating reagent in the microscopic reverse reaction.
