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Stabilizing Bifurcated Hydrogen Bond in 8-Aminoquinoline Appended Peptides. Chem Asian J 2024:e202400248. [PMID: 38701035 DOI: 10.1002/asia.202400248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Revised: 04/21/2024] [Accepted: 05/03/2024] [Indexed: 05/05/2024]
Abstract
The hydrogen bonding interaction between an amide N-H and the amide N of the preceding residue is prevalent in proline-containing proteins and peptides. However, the N-H···N hydrogen bonding interaction is rare in non-prolyl natural peptides due to restricted dihedral angles. Herein, we stabilize this type of interaction in 8-aminoquinoline appended non-prolyl peptides through bifurcated N···H···N hydrogen bond. The 8-aminoquinoline-incorporated model peptides 2a-i were designed, synthesized, and the crystal structures of 2a-c and 2i were solved. Analysis of crystal data reveals that the amide N-H of aminoquinoline is involved in bifurcated hydrogen bonding interaction with the nitrogen of the preceding amino acid residue and the nitrogen in quinoline. Analysis of crystal packing, Hirshfeld surface and fingerprint plots confirms that the intermolecular O···H contacts significantly contribute to stabilizing bifurcated N···H···N hydrogen bonding interaction. Furthermore, NMR experiments and CD spectroscopy were conducted to examine the preferred conformation in solution, and the data corroborate with the crystal structure conformation.
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2
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Copper/Zinc-Catalyzed Stitching of 2-Carbonylanilines with Bis(ynamides): Access to Pyrrolo[2,3- b]quinolines and Its Photophysical Studies. J Org Chem 2024; 89:6274-6280. [PMID: 38642061 DOI: 10.1021/acs.joc.4c00267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/22/2024]
Abstract
Herein, a one-pot desulfonylative protocol enabled by copper(II)/zinc(II) salts to access pyrrolo[2,3-b]quinolines in good to excellent yields from 2-carbonylanilines and ynamide-derived buta-1,3-diynes has been reported. Significantly, various 2-carbonylanilines carrying reactive functional groups are well tolerated. Moreover, a gram-scale synthesis and synthetic application highlight the practical utility of the current protocol. Notably, the fluorescence properties of pyrrolo[2,3-b]quinolines have been recorded, and their potential use as a fluorescent probe in the imaging of live cells has been demonstrated.
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3
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Regio- and Stereoselective Intermolecular 1,2-Difunctionalization of Terminal Alkynes: An Approach to Access ( Z)-β-Amidovinylsulfones. J Org Chem 2024; 89:2873-2884. [PMID: 38354303 DOI: 10.1021/acs.joc.3c02155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2024]
Abstract
We have developed the first I2/base-catalyzed regio- and stereoselective intermolecular β-amidosulfonylation of terminal alkynes using sodium sulfinates and quinoxalinone derivatives. The present methodology is compatible with a broad spectrum of various heterocyclic amides, terminal alkynes, and sodium sulfinates. It provides rapid access to valuable (Z)-β-amidovinyl sulfones at mild conditions. Moreover, the synthetic application of this methodology was demonstrated by the late-stage functionalization of numerous bioactive molecules.
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4
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Polycyclic Pyrazoles from Alkynyl Cyclohexadienones and Nonstabilized Diazoalkanes via [3 + 2]-Cycloaddition/[1,5]-Sigmatropic Rearrangement/Aza-Michael Reaction Cascade. Org Lett 2024; 26:839-844. [PMID: 38252505 DOI: 10.1021/acs.orglett.3c03967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
An efficient method for the stereoselective synthesis of "all center substituted" polycyclic pyrazoles from alkynyl cyclohexa-2,5-dienones and nonstabilized diazoalkanes via sequential [3 + 2]-cycloaddition/[1,5]-sigmatropic rearrangement and aza-Michael reactions is reported. The developed process is highly regioselective and stereoselective. It employs a wide substrate scope to furnish structurally diverse linear and bridged [4.4.n.0] ring-fused pyrazoles in moderate to good yields. One-pot and gram-scale syntheses and synthetic transformations have also been showcased.
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5
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Twofold Heteroannulation Reactions Enabled by Gold(I)/Zinc(II) Catalysts: Synthesis of Amine-Substituted Diaryl[ c, h][1,6]naphthyridines. Org Lett 2023; 25:7400-7405. [PMID: 37787541 DOI: 10.1021/acs.orglett.3c02899] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/04/2023]
Abstract
A straightforward and atom-economical one-pot protocol catalyzed by gold(I) and zinc(II) for the synthesis of amine-substituted diaryl[c,h][1,6]naphthyridines from two different aromatic nitriles has been showcased. This dual-catalytic strategy is highly efficient, offering an array of tetracyclic heteroaromatic products in good to excellent yields. Furthermore, the base can efficiently catalyze the second annulation step, yielding structurally unique thiophene-fused [1,6]naphthyridines in good yields.
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6
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Regioselective Synthesis of Phenanthridines via Pd(II)-Catalyzed Annulative C( sp2)-H Activation. J Org Chem 2023; 88:13568-13583. [PMID: 37738300 DOI: 10.1021/acs.joc.3c01234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/24/2023]
Abstract
A robust synthesis of phenanthridines has been described via Pd(II)-catalyzed domino C(sp2)-H activation/N-arylation using oxime esters with aryl acyl peroxides in a highly regioselective manner. This protocol is compatible with acetophenone as well as benzophenone-derived oxime esters and allows modular construction of functionalized phenanthridines with wide tolerance of electronic functionality. Further transformations were conducted to synthesize key building blocks, and control experiments were performed to understand the plausible reaction mechanism.
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7
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Regio- and Stereoselective Intermolecular Oxysulfonylation of Alkynes with 1,3-Diketones to Access ( Z)-β-Sulfonated Enethers. J Org Chem 2023; 88:13666-13677. [PMID: 37737722 DOI: 10.1021/acs.joc.3c01345] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/23/2023]
Abstract
The first multicomponent regio- and stereoselective difunctionalization of alkynes via concomitant C-O and C-S bond formation using 1,3-diketones and sodium sulfinate has been developed for the synthesis of various sulfonated enethers. The viability of this strategy is unveiled by gram-scale, various synthetic modifications and late-stage functionalization. This transformation does not require any prefunctionalization, metal catalysts, and oxidants. The present operationally simple, efficient, and sustainable approach provides various functionalized olefins in a one-pot protocol with high Z-selectivity.
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8
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Palladium(II)-Catalyzed Decarboxylative Difunctionalization of Alkynoic Acids To Access ( E)-β-Sulfonylacrylamides and DFT Study. Org Lett 2023; 25:6638-6642. [PMID: 37672675 DOI: 10.1021/acs.orglett.3c02415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/08/2023]
Abstract
A palladium(II)-catalyzed regio- and stereoselective difunctionalization of alkynoic acids has been achieved using sodium sulfinates and isocyanides to synthesize (E)-β-sulfonylacrylamides. The reaction proceeds via decarboxylative isocyanide addition, followed by sulfonylation. This three-component process works well with aromatic, heteroaromatic, and aliphatic alkynoic acids with good functional group tolerance and excellent regio- and stereoselectivity. DFT calculations were carried out to explain the reaction mechanism and the stereoselective formation of (E)-β-sulfonylacrylamides.
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9
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Leveraging Zn(II) Catalyst: Synthesis of Amidoquinolines via (3 + 3) Heteroannulation of Aromatic Amines and Ynamides. J Org Chem 2023. [PMID: 37466147 DOI: 10.1021/acs.joc.3c00568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/20/2023]
Abstract
Herein, we present a Zn(II)-catalyzed (3 + 3) heteroannulation reaction between aromatic amines and 1,3-diynamides for the synthesis of amidoquinolines. A large number of aromatic amines are well tolerated, furnishing quinoline derivatives in up to excellent yield. Notably, various reactive functional groups have survived under the optimal reaction conditions, highlighting the mildness of the developed protocol. In addition, amines derived from bioactive molecules show modest reactivity.
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10
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Nitrogen Atom Transfer Enables the (5+1) Annulation Reaction to Access Aminoisoquinolines. Org Lett 2023. [PMID: 37272676 DOI: 10.1021/acs.orglett.3c01258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Herein, a catalytic synthetic transformation offering a series of -NH2 group-bearing aminoisoquinolines with moderate to good yields has been showcased. Interestingly, the nitrogen atom of the isoquinoline ring is coming from the reaction medium upon metal-assisted C≡N bond cleavage. Moreover, this (5+1) annulation reaction shows broad substrate variation. Furthermore, the derivatization of the isoquinoline core via functional group interconversions and mechanistic studies to identify the reaction intermediate have been carried out successfully.
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11
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Metal-free transfer hydrogenation/cycloaddition cascade of activated quinolines and isoquinolines with tosyl azides. Chem Commun (Camb) 2023. [PMID: 37218434 DOI: 10.1039/d3cc01430d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The difficulty in isolating cyclic enamines emanating from their intrinsic instability has impeded their exploration in cycloaddition reactions. Here, we achieved a metal-free domino reaction providing quinoline and isoquinoline-derived cyclic amidines by the cycloaddition of azides with in situ generated enamines via dearomatization.
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Design and synthesis of N-acyl and dimeric N-Arylpiperazine derivatives as potential antileishmanial agents. Bioorg Chem 2023; 137:106593. [PMID: 37186964 DOI: 10.1016/j.bioorg.2023.106593] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 04/20/2023] [Accepted: 05/02/2023] [Indexed: 05/17/2023]
Abstract
The current regime for leishmaniasis is associated with several adverse effects, expensive, parenteral treatment for longer periods and the emergence of drug resistance. To develop affordable and potent antileishmanial agents, a series of N-acyl and homodimeric aryl piperazines were synthesized with high purity, predicted druggable properties by in silico methods and investigated their antileishmanial activity. The in vitro biological activity of synthesized compounds against clinically validated intracellular amastigote and extracellular promastigote form of Leishmania donovani parasite showed eight compounds inhibited 50% amastigotes growth below 25 µM. The half maximal inhibitory concentration (IC50) and cytotoxicity assessment of eight active compounds, 4a, 4d and 4e demonstrated activity with an IC50 2.0 - 9.1 µM and selectivity index 10 - 42. Compound 4d (IC50 2.0 µM, SI = 42) found to be the best among them with four-folds more potent and eight-folds less toxic than the control drug miltefosine. Overall, results demonstrated that compound 4d is a promising lead candidate for further development as antileishmanial drug.
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Catalyst-Controlled Diastereoselective Synthesis of Bridged [3.3.1] Bis(Indolyl)-Oxanes and Oxepanes via Desymmetrization of Bis(Indolyl)-Cyclohexadienones. Org Lett 2023; 25:3034-3039. [PMID: 37092788 DOI: 10.1021/acs.orglett.3c00834] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
Abstract
A catalyst-controlled divergent synthesis of bridged [3.3.1] bis(indolyl)-oxanes and cis-[6.7] fused bis(indolyl) oxepanes via diastereoselective desymmetrization of bis(indolyl)-cyclohexadienones is presented for the first time. The reaction is highly atom- and step-economic, furnishing sp3-rich functionalized bis(indolyl) derivatives in good to excellent yields with wide substrate scope. The reaction proceeds through Friedel-Crafts alkylation followed by catalyst-controlled selective C-C bond formation/rearrangement. Gram scale synthesis and synthetic utility to generate bis(indolyl) alkaloid-like molecular diversity were also illustrated.
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Synthesis of Azaspiro Tricyclic Scaffolds through Post‐Ugi Modifications: Scope and Limitation of Aza‐Michael Cyclization. European J Org Chem 2023. [DOI: 10.1002/ejoc.202300170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/02/2023]
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15
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Synthesis of Azaspiro Tricyclic Scaffolds through Post‐Ugi Modifications: Scope and Limitation of Aza‐Michael Cyclization. European J Org Chem 2023. [DOI: 10.1002/ejoc.202201293] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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16
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Palladium-Catalyzed Dearomative [4 + 2]-Cycloaddition toward Hydrocarbazoles. J Org Chem 2023; 88:97-105. [PMID: 36484797 DOI: 10.1021/acs.joc.2c01869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
An efficient method for the construction of hydrocarbazoles bearing three continuous sterically hindered stereocenters, two quaternary and one tertiary, via a highly diastereoselective palladium-catalyzed [4 + 2]-cycloaddition/dearomatization of 3-nitroindoles has been developed. The cycloaddition of 3-nitroindoles occurs at ambient conditions with a 1,4-zwitterionic intermediate, in situ generated from γ-methylidene-δ-valerolactones. The further synthetic utility of this method is demonstrated by the multifaceted transformations possible from the products. The catalytic asymmetric aspect of this transformation has also been explored.
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Additive-free synthesis of fused tricyclic cyanoisoxazolidines using in situ formed cyanonitrones. Chem Commun (Camb) 2023; 59:446-449. [PMID: 36519364 DOI: 10.1039/d2cc05831f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Herein, we disclose the first report on the generation of cyanonitrone in situ from diazoacetonitrile and nitrosoarene, and its subsequent [3+2] cycloaddition with oxabicyclic alkenes to access fused tricyclic cyanoisoxazolidines. Further, this methodology could be extended to access fused tricyclic trifluoromethylated and phosphonylated isoxazolidines. Surprisingly, the reductive ring-opening of cyanoisoxazolidines was followed by a spontaneous lactonization to produce fused tricyclic amino lactones. Moreover, the N-O bond of the obtained tricyclic trifluoromethylated isoxazolidines could be cleaved to obtain 1,3-amino alcohols.
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Influence of Proline Chirality on Neighbouring Azaproline Residue Stereodynamic Nitrogen Preorganization. Chem Asian J 2023; 18:e202201023. [PMID: 36349404 DOI: 10.1002/asia.202201023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Revised: 11/04/2022] [Indexed: 11/10/2022]
Abstract
We report herein the first systematic crystal structural investigation of azaproline incorporated in homo- and heterochiral diprolyl peptides. The X-ray crystallography data of peptides 1-5 illustrates that stereodynamic nitrogen in azaproline adopted the stereochemistry of neighbouring proline residue without depending on its position in the peptide sequence. Natural bond orbital analysis of crystal structures indicates OazPro -C'Pro of peptides 4 and 5 participating in n→π* interaction with stabilization energy about 1.21-1.33 kcal/mol. Density functional theory calculations suggested that the endo-proline ring puckering favoured over exo-conformation by 6.72-7.64 kcal/mol. NBO and DFT data reveals that the n→π* interactions and proline ring puckering stabilize azaproline chirality with the neighbouring proline stereochemistry. The CD, solvent titration, variable-temperature and 2D NMR experimental results further supported the crystal structures conformation.
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Visible Light Organo‐Photocatalytic Synthesis of 3‐Imidazolines. European J Org Chem 2022. [DOI: 10.1002/ejoc.202201079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Stereodivergent Synthesis of ( Z)-/( E)-β-Sulfonylacrylamides via Tandem Difunctionalization of Alkynes with Sulfinates and Isocyanides. Org Lett 2022; 24:7632-7636. [PMID: 36222482 DOI: 10.1021/acs.orglett.2c03092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Stereoselective difunctionalizations of the terminal and internal alkynes with various sulfinates and isocyanides have been achieved to prepare (Z)-/(E)-β-sulfonylacrylamides. The (Z)-β-sulfonylacrylamides were generated via a one-pot process that involves the reaction of terminal alkynes with sulfinates and isocyanides in the presence of iodine in sequential manner. The (E)-β-sulfonylacrylamides were prepared in a two-step synthesis via palladium(II)-catalyzed addition of isocyanide to (E)-β-iodovinylsulfones synthesized from alkynes.
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Regioselective Synthesis of Functionalized Pyrrolo[1,2- a]pyrazine-3,6(2 H,4 H)-diones via Tandem Post-Ugi Cyclization and Gold(I)-Catalyzed Annulation. J Org Chem 2022; 87:12799-12815. [PMID: 36149815 DOI: 10.1021/acs.joc.2c01404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A convenient synthesis of less explored pyrrolo[1,2-a]pyrazine-3,6(2H,4H)-diones is described in two steps from Ugi adducts. The method involves acid-mediated cyclization of Ugi adducts to form dihydropyrazinones followed by gold(I)-catalyzed regioselective annulation. The generality of the transformation was established by reacting a variety of substituted dihydropyrazinones under the optimized reaction conditions to form densely functionalized pyrrolo[1,2-a]pyrazine-3,6(2H,4H)-diones in good-to-excellent yields. It was also observed some of the acetone-derived Ugi adducts furnish 7-acyl-pyrroloimidazolones as a byproduct during TFA-mediated cyclization via alkyne-carbonyl metathesis and condensation.
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Catalytic Friedel-Crafts Alkylative Desymmetrization of Cyclohexa-2,5-dienones: Access to Linear and Bridged Polycyclic Pyrroles and 3-Arylpyrroles. Org Lett 2022; 24:5422-5427. [PMID: 35852460 DOI: 10.1021/acs.orglett.2c02135] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A catalytic [3 + 2]-cycloaddition/Friedel-Crafts alkylative desymmetrization strategy has been developed for the stereoselective construction of linear and bridged polycyclic pyrroles from alkynylcyclohexa-2,5-dienones. This strategy was further explored for the synthesis of 3-arylpyrroles under Brønsted acid catalysis. Reaction is highly chemo-, regio-, and stereoselective and is compatible with wide range of functionalized cyclohexa-2,5-dienones/pyrroles (>51 examples, ≤98% yields). Gram-scale synthesis and synthetic utility of the products have also been demonstrated to showcase the robustness of present method.
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Mechanisms behind the varying severity of Aleutian mink disease virus: Comparison of three farms with a different disease status. Vet Microbiol 2022; 270:109452. [DOI: 10.1016/j.vetmic.2022.109452] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Revised: 05/02/2022] [Accepted: 05/07/2022] [Indexed: 10/18/2022]
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Exploiting the umpolung reactivity of diazo groups: direct access to triazolyl-azaarenes from azaarenes. Chem Commun (Camb) 2022; 58:7062-7065. [PMID: 35648386 DOI: 10.1039/d2cc01897g] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The present work documents electrophilic substitution of azaarenes, mainly isoquinolines, with hypervalent iodine diazo reagents (HIDR) followed by formal [3+2]-dipolar cycloaddition in a tandem fashion. Other azaarenes viz. pyridines and phenanthridines too could be successfully used in the reaction. The methodology capitalizes on the umpolung nature of α-aryliodonio diazo compounds for installing a nucleophile, i.e. azaarene, at their α-position. Subsequent ylide formation and intramolecular 1,5-cyclization furnished 4,3-fused 1,2,4-triazolyl-azaarenes in good yields. The reaction is notable for its mild conditions, operational simplicity and fairly general scope.
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Copper-Catalyzed Oxidative [3 + 2]-Annulation of Quinoxalin-2(1 H)-one with Oxime Esters toward Functionalized Pyrazolo[1,5- a]quinoxalin-4(5 H)-ones as Opioid Receptor Modulators. J Org Chem 2022; 87:7350-7364. [PMID: 35587158 DOI: 10.1021/acs.joc.2c00563] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Pyrazolo[1,5-a]quinoxalin-4(5H)-one derivatives as novel opioid receptor modulators have been synthesized via copper-catalyzed oxidative [3 + 2]-annulation of quinoxalin-2(1H)-one and oxime-O-acetates. This hydrazine-free C-C and N-N bond formation strategy starts with the generation of C2N1 synthon using oxime acetate, which reacts in a [3 + 2] manner with quinoxalin-2(1H)-one, followed by oxidative aromatization. The synthesized compounds were tested against opioid receptors, of which eight compounds exhibited an antagonistic effect with EC50 < 5 μM at various opioid receptors. Molecular docking studies were performed to identify the binding of active pyrazolo[1,5-a]quinoxalin-4(5H)-one ligands with hKOR protein. Docking results indicated that compounds 3d and 3g participate in hydrogen bonding with the hydroxyl group of T111 of the active site pocket residue.
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PIDA‐Mediated Intramolecular N‐N Bond Formation to Access 2‐Aminoindazoles and 2,2′‐Biindazoles**. ChemistrySelect 2022. [DOI: 10.1002/slct.202201112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Palladium‐Catalyzed Intramolecular C‐H Heteroarylation to Access Fused Tricyclic Oxazolo[4,5‐c]Quinolines. ASIAN J ORG CHEM 2022. [DOI: 10.1002/ajoc.202200066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Organocatalytic asymmetric nitroso aldol reaction of α-substituted malonamates. Beilstein J Org Chem 2022; 18:217-224. [PMID: 35280951 PMCID: PMC8895028 DOI: 10.3762/bjoc.18.25] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 02/11/2022] [Indexed: 11/23/2022] Open
Abstract
A practical enantioselective N-selective nitroso aldol reaction of α-methylmalonamates with a nitrosoarene is reported. The reaction employs the Takemoto thiourea catalyst for the induction of enantioselectivity, and the corresponding optically active oxyaminated malonamates were obtained in reasonably good yields.
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Synergetic copper/zinc catalysis: synthesis of aryl/heteroaryl-fused 1 H-pyrrolo[3,2- c]pyridines. Chem Commun (Camb) 2022; 58:1974-1977. [PMID: 35044384 DOI: 10.1039/d1cc05514c] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Scaffolds having a 1H-pyrrolo[3,2-c]pyridine core show significant biological activity. Herein, we report a synergetic copper/zinc-catalyzed one-step annulation reaction of 2-amino (hetero)arylnitriles with ynamide-derived buta-1,3-diynes to deliver 1H-pyrrolo[3,2-c]quinoline-2,4-diamine derivatives in moderate to good yields. The annulation reaction follows a double cyclization pathway. The gram-scale synthesis of 1H-pyrrolo[3,2-c]quinoline-2,4-diamine proves the practicality of this protocol.
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Regioselective direct sulfenylation of glycals using arylsulfonyl chlorides in the presence of triphenylphosphine: access to C2-thioaryl glycosides. NEW J CHEM 2022. [DOI: 10.1039/d1nj05228d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Cheap and easily available arylsulfonyl chlorides as a sulfur source reductively couple with glycals in the presence of triphenylphosphine to afford C2-thioaryl glycosides.
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Copper-catalyzed cascade reaction of tryptamines with diazo compounds to access hexahydropyrroloindoline derivatives. Org Biomol Chem 2022; 20:8610-8614. [DOI: 10.1039/d2ob01635d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
A Cu-catalyzed cyclopropanation/ring-opening/iminium cyclization of tryptamine derivatives with donor–acceptor diazo compounds is developed to furnish pyrroloindolines, creating three consecutive stereogenic centers.
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Substrate-controlled product divergence in the reaction of α–fluoro–β-ketoamides with arynes. Chem Commun (Camb) 2022; 58:12987-12990. [DOI: 10.1039/d2cc04657a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An interesting substrate-controlled reactivity switch has been observed in the reaction of α-fluoro-β-ketoamides with arynes. The reaction of secondary α-fluoro-β-ketoamides with aryne provided access to α-aryl-α-fluoroacetamides through an arylation/deacylation sequence....
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33
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Synthesis and Crystal Structure Analysis of 3,3'-[(3-Sulfanyl Phenyl)Methylene]Bis(4-Hydroxy-2H-1-Benzopyran-2-One) : 5-Methyl-1,3-Thiazol-2(3H)-Imine. CRYSTALLOGR REP+ 2021. [DOI: 10.1134/s1063774521070166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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34
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Organo‐photocatalytic Synthesis of 6‐
β
‐Disubstituted Phenanthridines from
α
‐Diazo‐
β‐
Keto Compounds and Vinyl Azides. ASIAN J ORG CHEM 2021. [DOI: 10.1002/ajoc.202100518] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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35
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Cu(II)-Catalyzed C-N, C-O, C-Cl, C-S, and C-Se Bond Formation via C(sp 2)-H Activation Using 7-Azaindole as an Intrinsic Directing Group. J Org Chem 2021; 86:15185-15202. [PMID: 34696586 DOI: 10.1021/acs.joc.1c01811] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
A general protocol has been developed for the construction of carbon-heteroatom (C-N, C-Cl, C-O, C-S, and C-Se) bonds using the bench stable, earth-abundant, and environmentally benign copper catalyst. Only oxygen is sufficient to regenerate the copper catalyst. Control experiments suggested that the proto-demetalation step is reversible. Depending on the coupling partner, the reaction follows either disproportionation or radical pathways to complete the catalytic cycle. The synthetic utility of the developed protocol has been demonstrated via various functional group transformations.
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36
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PIDA-mediated oxidative aromatic C N bond cleavage: Efficient methodology for the synthesis of 1,2-diaza-1,3-dienes under ambient conditions. Tetrahedron Lett 2021. [DOI: 10.1016/j.tetlet.2021.153252] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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37
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Silver-Catalyzed Direct Synthesis of Trifluoromethylated Enaminopyridines and Isoquinolinones Employing Trifluorodiazoethane. Org Lett 2021; 23:5815-5820. [PMID: 34264078 DOI: 10.1021/acs.orglett.1c01969] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This Letter reports a Ag-catalyzed three-component approach for the N-alkenylation of 2-aminopyridines employing aldehydes and trifluorodiazoethane. Unlike the known reactions of trifluorodiazoethane with imines, which generate Mannich adducts, aziridines, or triazolines depending on the substrates and conditions, this reaction, after Mannich addition, proceeds via a carbene formation and 1,2-aryl migration sequence to afford (E)-enaminopyridines. This surprising selectivity, which is effective for a wide range of aldehydes and 2-aminopyridines, has been subsequently explored to access trifluoromethylated isoquinolinones.
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38
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Regioselective synthesis of functionalized pyrazole-chalcones via a base mediated reaction of diazo compounds with pyrylium salts. Org Biomol Chem 2021; 19:4132-4136. [PMID: 33870359 DOI: 10.1039/d1ob00274k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A base-mediated reaction of triaryl/alkyl pyrylium tetrafluoroborate salts with α-diazo-phosphonates, sulfones and trifluoromethyl compounds affords the corresponding functionalized pyrazole-chalcones as 5-P-5 and 3-P-3 tautomeric mixture. The reaction proceeds through an initial nucleophilic addition of diazo substrates to pyrylium salts followed by a base-mediated pyrylium ring-opening and intramolecular 1,5-cyclization to afford formal 1,3-dipolar cycloaddition products. The products underwent a Nazarov-type cyclization upon hydride reduction followed by acidic-workup, furnishing the corresponding indenyl-pyrazoles in high yields.
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39
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Effects of the COVID-19 pandemic on delivery of emergency surgical care in India. Br J Surg 2021; 108:e154-e155. [PMID: 33793717 PMCID: PMC7929169 DOI: 10.1093/bjs/znab004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 12/22/2020] [Indexed: 11/13/2022]
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40
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Additive‐Free Synthesis of Trifluoromethylated Spiro Cyclopropanes and Their Transformation into Trifluoromethylated Building Blocks. ASIAN J ORG CHEM 2021. [DOI: 10.1002/ajoc.202100207] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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41
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Ru(II)‐Catalyzed Regioselective Hydroarylative Coupling of Indolines with Internal Alkynes by C−H Activation. European J Org Chem 2021. [DOI: 10.1002/ejoc.202100085] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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42
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Base-Mediated Intramolecular Cyclization of α-Nitroethylallenic Esters as a Synthetic Route to 5-Hydroxy-3-pyrrolin-2-ones. J Org Chem 2021; 86:5630-5638. [PMID: 33788567 DOI: 10.1021/acs.joc.1c00109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
An unprecedented Cs2CO3-mediated intramolecular cyclization/rearrangement cascade that transforms α-nitroethylallenic esters to functionalized pyrrolin-2-ones has been uncovered. This reaction provides a new and practical approach for the synthesis of medicinally privileged 5-hydroxy-3-pyrrolin-2-ones under mild conditions. The broad potential of this new method was demonstrated by an efficient Au/Ag-catalyzed heteroarylation of 5-hydroxy-3-pyrrolin-2-ones employing electron-rich heteroarenes to furnish heteroaryl-lactam derivatives.
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43
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Redox-Neutral 1,3-Dipolar Cycloaddition of 2 H-Azirines with 2,4,6-Triarylpyrylium Salts under Visible Light Irradiation. J Org Chem 2021; 86:4661-4670. [PMID: 33677969 DOI: 10.1021/acs.joc.1c00082] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
A novel visible light mediated redox-neutral 1,3-dipolar cycloaddition of 2H-azirines with 2,4,6-triarylpyrylium tetrafluoroborate salts providing tetrasubstituted pyrroles has been developed. The 2,4,6-triarylpyrylium salt acts as dipolarophile as well as photosensitizer in the reaction, under blue light irradiation. The control experiments indicated single electron oxidation of 2H-azirines by photoexcited pyrylium salts, followed by coupling between an azaallenyl radical cation and triarylpyranyl radical as the key mechanistic feature. The mild conditions, wide substrate scope, and complete regioselectivity are the noticeable attributes of the reaction.
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44
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PPh
3
Catalyzed Post‐Transformation Ugi‐4CR Intramolecular Cyclization Reaction: One‐Pot Synthesis of Functionalized Spiropyrrolidinochromanones. ChemistrySelect 2021. [DOI: 10.1002/slct.202003936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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45
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Microwave-assisted efficient synthesis of pyrazole-fibrate derivatives as stimulators of glucose uptake in skeletal muscle cells. Bioorg Med Chem Lett 2021; 34:127760. [DOI: 10.1016/j.bmcl.2020.127760] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 12/09/2020] [Accepted: 12/20/2020] [Indexed: 01/05/2023]
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46
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Utilization of Unsymmetric Diaryliodonium Salts in α-Arylation of α-Fluoroacetoacetamides. Chem Asian J 2020; 15:4297-4301. [PMID: 33180366 DOI: 10.1002/asia.202001160] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 11/03/2020] [Indexed: 11/10/2022]
Abstract
The use of unsymmetric diaryliodonium salts as a versatile class of arylating agents has been demonstrated by developing a novel strategy to quickly access α-arylated α-fluoroacetoacetamides. The protocol provides a convenient metal-free method for the α-arylation of a diverse class of fluorinated acetoacetamides, and the products are obtained in good yields. The strategy, upon use of electron-deficient diaryliodonium salts as an arylating agent, provides α-fluoroacetamides through a spontaneous arylation/deacylation cascade.
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47
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Decarboxylative/Oxidative Amidation of Aryl α-Ketocarboxylic Acids with Nitroarenes and Nitroso Compounds in Aqueous Medium. Org Lett 2020; 22:9381-9385. [PMID: 33206540 DOI: 10.1021/acs.orglett.0c03666] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The decarboxylative/oxidative amidation of aryl α-ketocarboxylic acids with 5-aryl-3-nitroisoxazole-4-carboxylates and substituted dinitrobenzenes under oxidative aqueous conditions to afford N-aryl amides is described. The reaction is suggested to proceed via a radical pathway in which a benzoyl nitroxyl radical, the key intermediate formed from reaction between nitroarene and benzoyl radical from glyoxalic acid, couples with hydroxyl radical from water to produce amide. Mechanistic insight allowed the scope of the strategy to be expanded to the synthesis of amides via reaction between aryl α-ketocarboxylic acids and nitroso compounds.
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48
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A decade of acute encephalitis syndrome (AES) cases in eastern Uttar Pradesh, India: etiological scenario and preventive strategies (2010–2019). Int J Infect Dis 2020. [DOI: 10.1016/j.ijid.2020.11.066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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49
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Ruthenium(II)‐Catalyzed Synthesis of Indolo[2,1‐a]isoquinolines through Double Oxidative Annulation Reaction of Phenyl Isocyanates with Di(hetero)aryl Alkynes. Adv Synth Catal 2020. [DOI: 10.1002/adsc.202000963] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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50
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Hantzsch Ester-Mediated Synthesis of Phenanthridines under Visible-Light Irradiation. Chem Asian J 2020; 15:3513-3518. [PMID: 32935472 DOI: 10.1002/asia.202000888] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 09/09/2020] [Indexed: 01/08/2023]
Abstract
An efficient photocatalytic synthesis of phenanthridines mediated by an organo-photoredox initiator Hantzsch ester has been developed via denitrogenative intramolecular annulation of benzotriazolyl chalcones. The highly reducing photoactivated Hantzsch ester facilitates the transformation of benzotriazolyl chalcones into phenanthridinyl chalcones through photoinduced electron transfer (PET) and hydrogen atom transfer (HAT) processes. The mild reaction conditions utilizing inexpensive Hantzsch ester as photosensitizer, wide reaction scope and excellent functional group tolerance are notable attributes of the methodology.
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