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1. Construction of Fused Tetrahydroquinolines by Catalytic Hydride-Transfer-Initiated Tandem Functionalization of Quinolines

Author:
Rongqing Guan; He Zhao; Min Zhang
Source:
Organic letters 2022 v.24 no.16 pp. 3048-3052
ISSN:
1523-7052
Subject:
indoles,   etc   ; feedstocks; quinoline;     Show all 3 Subjects
Abstract:
... Herein, we present a new annulation reaction of quinolinium salts with indoles and paraformaldehyde, which enables syn-diastereoselective construction of a vast range of fused tetrahydroquinolines via ruthenium-catalyzed hydride-transfer-initiated tandem functionalization of the quinoline skeleton. The developed transformation proceeds with mild reaction conditions, good substrate and functional g ...
DOI:
10.1021/acs.orglett.2c01001

2. Phosphine-Mediated Sequential [2+4]/[2+3] Annulation to Construct Pyrroloquinolines

Author:
Junhui Lin; Yannan Zhu; Wei Cai; You Huang
Source:
Organic letters 2022 v.24 no.8 pp. 1593-1597
ISSN:
1523-7052
Subject:
indoles,   etc   ; diastereoselectivity; stoichiometry;     Show all 3 Subjects
Abstract:
... A domino [2+4]/[2+3] sequential annulation reaction of MBH carbonates with N-unprotected indoles has been developed to provide various pyrroloquinoline derivatives in ≤94% yield and 20:1 dr. The reaction could be either mediated by stoichiometric PCy₃ or catalyzed by R₃PO via Pᴵᴵᴵ/Pⱽ═O redox cycling in the presence of phenylsilane. This method assembles polycyclic 1,7-fused indoles in one step dia ...
DOI:
10.1021/acs.orglett.1c04388

3. Ag(I)-Promoted, Diastereoselective Cyclo-isomerization of N-Alkynyl-7-azaindole-2-carbinols. Selective Synthesis of syn-1,2-Diarylpyrrolo[1,2-a]indol-3-ones and (Z)-8-Benzylideneoxazolo[3′,4′’:1,5]pyrrolo[2,3-b]pyridines

Author:
Bhavna Yadav; Beeraiah Baire
Source:
Organic letters 2022 v.24 no.29 pp. 5450-5455
ISSN:
1523-7052
Subject:
indoles,   etc   ; diastereoselectivity; pyridines;     Show all 3 Subjects
Abstract:
... The design and development of an Ag(I)-promoted, highly diastereoselective cycloisomerization strategy for the synthesis of syn-1,2-diarylpyrrolo[1,2-a]indol-3-ones from N-alkynyl-indole-2-carbinols is reported. The H₂¹⁸O control experiment and identification of ¹⁸O-labeled product suggested the involvement of an external water. The 7-azaindole substrates showned a distinct reactivity to give the ...
DOI:
10.1021/acs.orglett.2c02179

4. Chiral Brønsted Acid-Catalyzed Intramolecular Asymmetric Allylic Alkylation of Indoles with Primary Alcohols

Author:
Lei-Ming Zou; Xian-Yun Huang; Chao Zheng; Yuan-Zheng Cheng; Shu-Li You
Source:
Organic letters 2022 v.24 no.19 pp. 3544-3548
ISSN:
1523-7052
Subject:
indoles,   etc   ; alkylation; enantioselectivity;     Show all 3 Subjects
Abstract:
... Herein, chiral Brønsted acid-catalyzed intramolecular asymmetric allylic alkylation of indoles with allylic primary alcohols is described. The allyl alcohols were directly employed as the allylic precursors in this metal-free protocol, without preactivation or any additional activating reagents. This method provides the convenient synthesis of a broad range of functionalized tetrahydrocarbazoles i ...
DOI:
10.1021/acs.orglett.2c01253

5. Recent advances in the synthesis of thienoindole analogs and their diverse applications

Author:
Shubham Pandey; Simran Aggarwal; Ritu Choudhary; Satish K. Awasthi
Source:
RSC advances 2022 v.12 no.25 pp. 15787-15813
ISSN:
2046-2069
Subject:
indoles,   etc   ; humans; moieties;     Show all 3 Subjects
Abstract:
... Thiophene-fused heterocyclic organosulfur systems, especially the thieno[3,2-b]indole moiety have attracted significant attention because they show a wide spectrum of biological activities such as antituberculosis, antitumor, antifungal, antibacterial, and human 5-HT5A receptor binding inhibition. Moreover, they also find applications in material chemistry and chemical engineering. Thus, due to th ...
DOI:
10.1039/d1ra09233b

6. An acid-promoted pseudocine substitution manifold of γ-aminocyclopentenone enables divergent access to polycyclic indole derivatives

Author:
Biplab Mondal; Chenna Jagadeesh; Dinabandhu Das; Jaideep Saha
Source:
Chemical communications 2022 v.58 no.15 pp. 2504-2507
ISSN:
1364-548X
Subject:
indoles,   etc   ; regioselectivity; stereoselectivity;     Show all 3 Subjects
Abstract:
... We demonstrated γ-aminocyclopentenones to be a suitable surrogate for reactive cyclopentadienone via a pseudocine-substitution manifold. This approach enabled its orchestrated annulation with “tailored” bis-nucleophiles and to furnish complex β,γ-annulated cyclopentanoids or indole-based polycyclic architectures. This strategy represents a generalized means for direct, regioselective and stereosel ...
DOI:
10.1039/d1cc06883k

7. Cascade of C(sp²)–H Addition to Carbonyl and C(sp²)–CN/C(sp²)–H Coupling Enabled by Brønsted Acid: Construction of Benzo[a]carbazole Frameworks

Author:
Ling Tang; Shuangshuang Jiang; Xinmiao Huang; Zhiyong Song; Jian-bo Wang; Ming Ma; Bo Chen; Yuanhong Ma
Source:
Organic letters 2022 v.24 no.17 pp. 3232-3237
ISSN:
1523-7052
Subject:
indoles,   etc   ; acids; couplings;     Show all 3 Subjects
Abstract:
... Herein, we report an unprecedented cascade reaction of C(sp²)–H addition to carbonyl and the C(sp²)–CN/C(sp²)–H coupling of 2-(2-oxo-2-arylethyl)benzonitriles with indoles enabled by commercially available TsOH·H₂O. The protocol represents the first metal-free C(sp²)–CN/C(sp²)–H coupling, affording a new route for the synthesis of various benzo[a]carbazole derivatives with a broad substrate scope, ...
DOI:
10.1021/acs.orglett.2c01027

8. Efficient thiocyanation of aromatic compounds using NH4SCN, DMSO and H2SO4 [Erratum: 2022 ; p.154017]

Author:
Mohammad Abbasi; Najmeh Nowrouzi; Hamed Sedaghat
Source:
Tetrahedron letters 2022 v.101 no. pp. 153929
ISSN:
0040-4039
Subject:
indoles,   etc   ; aniline; phenol;     Show all 3 Subjects
Abstract:
... A simple, efficient, and smooth thiocyanation of indoles, phenols and aniline derivatives using NH₄SCN, DMSO and H₂SO₄ in DMF is introduced. Using this procedure, diverse indoles and N-alkyl indoles are selectively thiocyanated at the C-3 position. para-free anilines, N-alkyl anilines and phenols undergo thiocyanation at the para position selectively. ...
DOI:
10.1016/j.tetlet.2022.153929

9. Asymmetric Divergent Total Syntheses of (+)-Decursivine and (+)- Serotobenine via Intramolecular Fischer Indole Synthesis

Author:
Dong-Hyun Kim; Hyo-Mi Kim; Ji-Su Lim; Hyun-Woo Lee; Cheon-Gyu Cho
Source:
Organic letters 2022 v.24 no.15 pp. 2873-2877
ISSN:
1523-7052
Subject:
indoles,   etc   ; amines; stereoselective synthesis;     Show all 3 Subjects
Abstract:
... A new asymmetric synthetic route to (+)-decursivine and (+)-serotobenine is formulated. The key developments are the de novo construction of the crucial eight-membered 3,4-fused tricyclic indole ring engaged by the intramolecular Fischer indole synthesis and the stereocontrolled assembly of the dihydrobenzofuran subunit mediated by the asymmetric intramolecular Rh-carbenoid C–H insertion. BF₃-medi ...
DOI:
10.1021/acs.orglett.2c00848

10. DMSO–allyl bromide: a mild and efficient reagent for atom economic one-pot N-allylation and bromination of 2°-aryl amines, 2-aryl aminoamides, indoles and 7-aza indoles

Author:
Suresh Snoxma Smile; Motakatla Novanna; Sathananthan Kannadasan; Ponnusamy Shanmugam
Source:
RSC advances 2022 v.12 no.3 pp. 1834-1839
ISSN:
2046-2069
Subject:
indoles,   etc   ; bromination; reaction mechanisms;     Show all 3 Subjects
Abstract:
... A mixture DMSO–allyl bromide has been developed as a reagent for an atom economic one-pot N-allylation and aryl bromination under basic conditions. Utilizing this reagent, N-allylation–bromination of a number of 2°-aryl amines, aryl aminoamides, indoles, and 7-aza indoles has been achieved. The scope of the substrates and limitations, the synthetic utility of the products, and a plausible reaction ...
DOI:
10.1039/d1ra08588c

11. Tailored Solvatochromic NIR Phosphorus-Chromophores via Selective P−N and P−C Chemistry in P-Heteropines

Author:
Zi Yang; Xinyu Li; Kai Yang; Zhikai Zhang; Yankun Wang; Na Yu; Thomas Baumgartner; Yi Ren
Source:
Organic letters 2022 v.24 no.10 pp. 2045-2049
ISSN:
1523-7052
Subject:
indoles,   etc   ; chemical structure; phosphorus;     Show all 3 Subjects
Abstract:
... Herein we report selective P–C and P–N chemistry as a new synthetic tool for constructing phosphorus (P)-chromophores with rich chemical structures. Our studies reveal that isomeric structures significantly influence the chemical structure and electronic communication of P-heteropines, which results in efficient tunability of the photophysical properties. In particular, isomeric P-chromophores wit ...
DOI:
10.1021/acs.orglett.2c00570

12. A short total synthesis of (±)-mersicarpine via visible light-induced cascade photooxygenation

Author:
Mario Frahm; Alice Voss; Malte Brasholz
Source:
Chemical communications 2022 v.58 no.36 pp. 5467-5469
ISSN:
1364-548X
Subject:
indoles,   etc   ; alkaloids; chemical communication;     Show all 3 Subjects
Abstract:
... A short total synthesis of the Kopsia alkaloid (±)-mersicarpine is presented. As the key step, a visible light-induced catalytic cascade photooxygenation was utilized, to convert a 3,3-disubstituted tetrahydrocarbazole intermediate, in one step, into a perhydropyrido[1,2-a]indole dione as the immediate precursor to the natural product. The synthesis of mersicarpine was achieved with an overall yie ...
DOI:
10.1039/d2cc01316a

13. A tunable synthesis of indigoids: targeting indirubin through temperature

Author:
James A. Shriver; Kaylie S. Kaller; Ally L. Kinsey; Katelyn R. Wang; Summer R. Sterrenberg; Madison K. Van Vors; Joshua T. Cheek; John S. Horner
Source:
RSC advances 2022 v.12 no.9 pp. 5407-5414
ISSN:
2046-2069
Subject:
indoles,   etc   ; indigo; molybdenum; temperature;     Show all 4 Subjects
Abstract:
... The spontaneous conversion of 3-indoxyl to indigo is a well-established process used to produce indigo dyes. It was recently shown that some indoles, when reacted with molybdenum hexacarbonyl and cumyl peroxide, proceed through an indoxyl intermediate to produce significant amounts of indirubin through a competing mechanism. Modulation of this system to lower temperatures allows for careful tuning ...
DOI:
10.1039/d2ra00400c

14. Access to Azepino-Annulated Benzo[c]carbazoles Enabled by Gold-Catalyzed Hydroarylation of Alkynylindoles and Subsequent Oxidative Cyclization

Author:
Jin-Ming Yang; Meng-Lian Yao; Jun-Chi Li; Ji-Kai Liu; Bin Wu
Source:
Organic letters 2022 v.24 no.36 pp. 6505-6509
ISSN:
1523-7052
Subject:
indoles,   etc   ; carbazoles; gold; oxidation;     Show all 4 Subjects
Abstract:
... Herein, we report a facile and efficient synthetic method to construct azepino[1,2-a]indoles through a novel gold(I)-catalyzed intramolecular hydroarylation of alkynylindoles. A wide range of functional groups can be well tolerated in this transformation, and the corresponding highly functionalized azepino[1,2-a]indole skeletons were obtained in moderate to excellent yields. Subsequent oxidation o ...
DOI:
10.1021/acs.orglett.2c02293

15. Acid-promoted intra- and intermolecular [2+2] cycloaddition of indoles to aryl alkynes to access cyclobutene-fused indolines

Author:
Qing Wang; Sen-Lin Wang; Jin-Bao Fan; Guang-Yao Zeng; Ying-Jun Zhou; Xu Deng
Source:
Chemical communications 2022 v.58 no.66 pp. 9270-9273
ISSN:
1364-548X
Subject:
indoles,   etc   ; alkynes; cycloaddition reactions;     Show all 3 Subjects
Abstract:
... Herein, we have reported the first example of both intra- and intermolecular [2+2] cycloaddition of the electron-rich indoles and unactivated aryl alkynes promoted by the combination of Fe(NO₃)₃ and HNO₃, which highlights efficient and selective access to several different types of functionalized cyclobutene-fused indolines from readily available starting materials with cheap catalysts and simple ...
DOI:
10.1039/d2cc02840a

16. Atroposelective Synthesis of Axially Chiral C2-Arylindoles via Rhodium-Catalyzed Asymmetric C–H Bond Insertion

Author:
Junheng Liu; Qiongya Li; Ying Shao; Jiangtao Sun
Source:
Organic letters 2022 v.24 no.25 pp. 4670-4674
ISSN:
1523-7052
Subject:
indoles,   etc   ; chelation; stereoselective synthesis;     Show all 3 Subjects
Abstract:
... A highly efficient rhodium-catalyzed formal C–H insertion reaction between indoles and 1-diazonaphthoquinones has been established, providing a novel protocol for the atroposelective synthesis of axially chiral C2-arylindoles (up to 99:1 er) under mild reaction conditions. Typically, only 1 mol % of Rh₂(S-PTTL)₄ is used and the chelation group is not needed for this conversion. ...
DOI:
10.1021/acs.orglett.2c01818

17. Direct Bis-Alkyl Thiolation for Indoles with Sulfinothioates under Pummerer-Type Conditions

Author:
Peng Qi; Fang Sun; Ning Chen; Hongguang Du
Source:
Journal of organic chemistry 2022 v.87 no.2 pp. 1133-1143
ISSN:
1520-6904
Subject:
indoles,   etc   ; anhydrides; organic chemistry;     Show all 3 Subjects
Abstract:
... A base-free bis-alkyl thiolation reaction of indoles with sulfinothioates under Pummerer-type conditions is described. Sulfinothioates, activated with 2,2,2-trifluoroacetic anhydride, are demonstrated to be an efficient thiolation reagent for wide applications. This approach enabled double C–H thiolation at the C2 and C3 of the indole in one pot. The mechanism studies suggested the thiolation was ...
DOI:
10.1021/acs.joc.1c02502

18. Electrochemical Dearomatization of Indoles: Access to Diversified Fluorine-Containing Spirocyclic Indolines

Author:
Kangdong Mo; Xiaocong Zhou; Ju Wu; Yufen Zhao
Source:
Organic letters 2022 v.24 no.15 pp. 2788-2792
ISSN:
1523-7052
Subject:
indoles,   etc   ; chemical reactions; electrochemistry;     Show all 3 Subjects
Abstract:
... A robust and green electrochemical dearomatization of indoles was developed by merging a fluorine-containing group to an indole nucleus under oxidant-free conditions, delivering a diverse array of tri- and difluoromethylated 3,3-spiroindolines with good functional group tolerance. ...
DOI:
10.1021/acs.orglett.2c00530

19. Palladium-Catalyzed Asymmetric Dearomative Carbonylation of Indoles

Author:
Qiuyu Li; Yunchu Zhang; Yuye Zeng; Yujing Fan; Aijun Lin; Hequan Yao
Source:
Organic letters 2022 v.24 no.16 pp. 3033-3037
ISSN:
1523-7052
Subject:
indoles,   etc   ; chemical reactions; enantioselectivity;     Show all 3 Subjects
Abstract:
... Herein, we disclose a strategy for the asymmetric dearomatization of N-arylacyl indoles via a palladium-catalyzed tandem Heck/carbonylation, leading to an array of indoline-3-carboxylates bearing vicinal C2-aza-quaternary and C3 tertiary stereocenters in high yields and excellent enantio- and diastereoselectivities. This study is an important advance in the field of asymmetric carbonylation and en ...
DOI:
10.1021/acs.orglett.2c00962

20. Synthesis of 2,3-Bis(trifluoromethylseleno) Indoles through an Oxidative Copper-Mediated Domino Reaction

Author:
Hui Wang; Yunfei Yao; Zipeng Zhang; Yangjie Huang; Zhiqiang Weng
Source:
Journal of organic chemistry 2022 v.87 no.5 pp. 3605-3612
ISSN:
1520-6904
Subject:
indoles,   etc   ; organic chemistry; oxidation;     Show all 3 Subjects
Abstract:
... An oxidative copper-mediated double trifluoromethylselenolation of terminal 2-alkynylanilines using [(bpy)CuSeCF₃]₂ is reported, providing a moderately efficient and convenient approach to 2,3-bis(trifluoromethylseleno)indoles. Mechanistic studies show that a cascade sequence of oxidation, trifluoromethylselenolation, 5-endo-dig cyclization, and elimination is involved in this transformation. ...
DOI:
10.1021/acs.joc.1c03156