Deoxygenative C2-heteroarylation of quinoline N-oxides: facile access to α-triazolylquinolines

• Geetanjali S. Sontakke,
• Rahul K. Shukla and
• Chandra M. R. Volla

Beilstein J. Org. Chem. 2021, 17, 485–493, doi:10.3762/bjoc.17.42

• simplicity of the developed protocol. The current transformation was also found to be compatible for the late-stage modification of natural products. Keywords: amination; heteroarylation; quinoline N-oxides; regioselective; triazoles; Introduction Quinoline is a key heterocyclic moiety found in many

• ][37][38][39][40][41][42][43][44][45]. For example, Yin and co-workers developed a protocol for the deoxygenative C2-amination of pyridine/quinoline N-oxides using t-BuNH2 and Ts2O/TFA in 2007 (Scheme 1a) [48]. Later, Londregan and co-workers were successful in achieving C2-amination employing

• derivatives is highly desired. The continuous interest and efforts of our group for the derivatization of quinoline moieties [57] and use of N-sulfonyl-1,2,3-triazoles as heterocyclic precursors encouraged us to develop a new strategy for the regioselective C2-triazolylation of quinoline N-oxide under mild

CF₃-substituted carbocations: underexploited intermediates with great potential in modern synthetic chemistry

• Anthony J. Fernandes,
• Armen Panossian,
• Bastien Michelet,
• Agnès Martin-Mingot,
• Frédéric R. Leroux and
• Sébastien Thibaudeau

Beilstein J. Org. Chem. 2021, 17, 343–378, doi:10.3762/bjoc.17.32

• , affording biaryl species 161. Using this strategy, several trifluoromethyl ketones 162 and alcohols 163 bearing heteroaryl substituents (i.e., benzothiazole, quinoline, isoquinoline, benzimidazole, or imidazole) prone to be protonated were elegantly converted into the corresponding alcohols 163 and biphenyl

Decarboxylative trifluoromethylthiolation of pyridylacetates

• Ryouta Kawanishi,
• Kosuke Nakada and
• Kazutaka Shibatomi

Beilstein J. Org. Chem. 2021, 17, 229–233, doi:10.3762/bjoc.17.23

• gave the desired products 2e–g in moderate yields. The method could also be applied to substrates with quinoline and isoquinoline backbones to afford the corresponding products 2h and 2i. In addition, the reaction of α-monosubstituted 2-pyridylacetate 8 was performed to yield the corresponding mono

Synthesis of imidazo[1,5-a]pyridines via cyclocondensation of 2-(aminomethyl)pyridines with electrophilically activated nitroalkanes

• Dmitrii A. Aksenov,
• Nikolai A. Arutiunov,
• Vladimir V. Maliuga,
• Alexander V. Aksenov and
• Michael Rubin

Beilstein J. Org. Chem. 2020, 16, 2903–2910, doi:10.3762/bjoc.16.239

• -(bromomethyl)quinoline (21c) was prepared from commercially available 6-bromo-2-methylquinoline (22c, via radical bromination in the presence of NBS and dibenzoyl peroxide [51]. To this end, the methylquinoline 22c (3.33 g, 15 mmol) was dissolved in carbon tetrachloride (30 mL), and N-bromosuccinimide (2.94 g

• was concentrated in vacuum. The crude product was purified by flash column chromatography eluting with EtOAc/petroleum ether 1:6. Then, the amine was afforded via a Gabriel synthesis using a modified protocol described in the literature [52]. To a stirred solution of 6-bromo-2-(bromomethyl)quinoline

• , 118.5, 113.5; ATR-FTIR (ZnSe) νmax: 3066, 1749, 1676, 1603, 1473, 1458, 1433, 1358, 1305, 1251, 1267, 1120 cm−1; HRESIMS (TOF) m/z: [M + H]+ calcd for C13H11N2, 195.0917; found, 195.0918. 6-Bromo-7-methoxyimidazo[1,5-a]quinoline (19de) The title compound was obtained via the typical procedure 2

Synthesis and characterization of S,N-heterotetracenes

• Astrid Vogt,
• Florian Henne,
• Christoph Wetzel,
• Elena Mena-Osteritz and
• Peter Bäuerle

Beilstein J. Org. Chem. 2020, 16, 2636–2644, doi:10.3762/bjoc.16.214

• -substituted thienopyrrole 26, saponification to carbonic acid 27, and subsequent Cu-mediated decarboxylation in quinoline resulted in thienopyrrole 28 in more than 80% yield over three steps. Lithiation of 28 with n-BuLi and reaction with TIPS chloride selectively occurred at the thiophene α-position to give

Recent synthesis of thietanes

• Jiaxi Xu

Beilstein J. Org. Chem. 2020, 16, 1357–1410, doi:10.3762/bjoc.16.116

Copper-based fluorinated reagents for the synthesis of CF₂R-containing molecules (R ≠ F)

• Louise Ruyet and
• Tatiana Besset

Beilstein J. Org. Chem. 2020, 16, 1051–1065, doi:10.3762/bjoc.16.92

• ). The reaction was efficient (65 examples, up to 97% yield), showed a good functional group tolerance (i.e., cyano, ester, ketone) and even heteroarenes such as pyridine, quinoline and quinoxaline were functionalized with the four fluorinated moieties (Scheme 17). In situ-generated copper-based

Fluorinated phenylalanines: synthesis and pharmaceutical applications

• Laila F. Awad and
• Mohammed Salah Ayoup

Beilstein J. Org. Chem. 2020, 16, 1022–1050, doi:10.3762/bjoc.16.91

• other hand, when the quinoline-based ligand 162 was used, it was shown to promote the palladium-catalyzed direct electrophilic fluorination of β-methylene C(sp3)–H bonds. Thus, fluorinations of ʟ-phenylalanine 4-trifluoromethylphenylamides 161a–l carrying a range of functional groups such as fluoro

• -fluorinated Phe derivatives using quinoline-based ligand 162 in the Pd-catalyzed direct fluorination of β-methylene C(sp3)–H bonds. Synthesis of β,β-difluorophenylalanine derivatives from 2,2-difluoroacetaldehyde derivatives 164a,b. Synthesis of β,β-difluorophenylalanine derivatives via an imine chiral

Combining enyne metathesis with long-established organic transformations: a powerful strategy for the sustainable synthesis of bioactive molecules

• Valerian Dragutan,
• Ileana Dragutan,
• Albert Demonceau and
• Lionel Delaude

Beilstein J. Org. Chem. 2020, 16, 738–755, doi:10.3762/bjoc.16.68

• aminohydroxylation. For this purpose, they first prepared the properly functionalized (–)-quinines from quinoline derivatives in six steps. These chiral intermediates were then submitted to an enyne metathesis reaction with the Grubbs first-generation Ru catalyst (10 mol %), under an ethylene atmosphere, to generate

A systematic review on silica-, carbon-, and magnetic materials-supported copper species as efficient heterogeneous nanocatalysts in “click” reactions

• Pezhman Shiri and
• Jasem Aboonajmi

Beilstein J. Org. Chem. 2020, 16, 551–586, doi:10.3762/bjoc.16.52

Recent advances in photocatalyzed reactions using well-defined copper(I) complexes

• Mingbing Zhong,
• Xavier Pannecoucke,
• Philippe Jubault and
• Thomas Poisson

Beilstein J. Org. Chem. 2020, 16, 451–481, doi:10.3762/bjoc.16.42

• -a]pyrrolo[3,4-c]quinoline derivatives were obtained for the first time. This transformation starts with the oxidation of the excited photocatalyst with O2. The aniline is then oxidized into an N-centered radical cation, which further gives the α-amino radical. The latter reacts with the maleimide to

Architecture and synthesis of P,N-heterocyclic phosphine ligands

• Wisdom A. Munzeiwa,
• Bernard Omondi and
• Vincent O. Nyamori

Beilstein J. Org. Chem. 2020, 16, 362–383, doi:10.3762/bjoc.16.35

• -quinolyhydrazine (112) at a molar ratio of 2:1 in the presence of a base gave compound 113 in very good yield. Heating of compound 113 in toluene induced isomerization where the pendant arm is shifted to the quinoline ring via a P–C migration to obtain compound 114. The corresponding P–N and P–P rearrangements

Experimental and computational electrochemistry of quinazolinespirohexadienone molecular switches – differential electrochromic vs photochromic behavior

• Eric W. Webb,
• Jonathan P. Moerdyk,
• Kyndra B. Sluiter,
• Benjamin J. Pollock,
• Amy L. Speelman,
• Eugene J. Lynch,
• William F. Polik and
• Jason G. Gillmore

Beilstein J. Org. Chem. 2019, 15, 2473–2485, doi:10.3762/bjoc.15.240

• photochemistry of two closely related and more reducible quinazolinespirohexadienones (QSHDs), wherein the naphthalene of the PSHD is replaced with a quinoline. In the present work, we report our investigation of the electrochemistry of these asymmetric QSHDs. In addition to the short wavelength and photochromic

• substrates [11][12][13][14][15], or vinylcarbazole or alkoxystyrene derivatives for radical cation cylcloaddition and polymerization reactions [16][17][18][19][20]). We thus proposed the replacement of the naphthalene in 1a with a more electron-deficient quinoline ring. Due to the saturated spirocyclic

• carbon insulating the dienone electrophore from the quinoline moiety in the SW form, we expected minimal change in the SW reduction potential relative to the PSHDs, but a significant difference for the completely conjugated LW isomer(s). Previously we reported the detailed synthesis of two novel

Self-assembled coordination thioether silver(I) macrocyclic complexes for homogeneous catalysis

• Zhen Cao,
• Aline Lacoudre,
• Cybille Rossy and
• Brigitte Bibal

Beilstein J. Org. Chem. 2019, 15, 2465–2472, doi:10.3762/bjoc.15.239

• /cycloisomerization was previously described in high yields (>95%) using 5 mol % catalyst loadings starting from 2-(alkynyl)quinoline-3-carbaldehyde [60][61] with AgOTf catalyst and starting from 2-alkynylbenzaldehyde derivatives [62] in the presence of a macrocyclic pyridine-tetraaza complex of Ag(I) as a catalyst

Cyclopropanation–ring expansion of 3-chloroindoles with α-halodiazoacetates: novel synthesis of 4-quinolone-3-carboxylic acid and norfloxacin

• Sara Peeters,
• Linn Neerbye Berntsen,
• Pål Rongved and
• Tore Bonge-Hansen

Beilstein J. Org. Chem. 2019, 15, 2156–2160, doi:10.3762/bjoc.15.212

• : catalysis; cyclopropanation; indole; norfloxacin quinoline; quinolone; Rh(II); ring expansion; Introduction The development and use of metal carbenes occupy a central part in the field of the C–H functionalization [1]. Among the metal carbenes, the transient Rh carbenes, usually made by Rh-catalyzed

• . These halo-acceptor carbenoids undergo cyclopropanation of N–H indoles with high selectivity, and only traces of C–H or N–H insertion products were observed. The yield of ethyl quinoline-3-carboxylate is dependent on the halogen in X-EDA (Cl: 90%, Br: 84%, I: 70%). The reaction works well for

• substituted indoles with R-groups in positions 3–7. When R at position 8 = Cl, the reaction was sluggish, and when R at position 2 = Me there was no quinoline formed. The overall transformation is formally a cyclopropanation of the indole C2–C3 double bond followed by a spontaneous ring expansion of the

Regioselective Pd-catalyzed direct C1- and C2-arylations of lilolidine for the access to 5,6-dihydropyrrolo[3,2,1-ij]quinoline derivatives

• Hai-Yun Huang,
• Haoran Li,
• Thierry Roisnel,
• Jean-François Soulé and
• Henri Doucet

Beilstein J. Org. Chem. 2019, 15, 2069–2075, doi:10.3762/bjoc.15.204

• ; Introduction Lilolidine (Figure 1, left), which is a commercially available compound, contains a 5,6-dihydropyrrolo[3,2,1-ij]quinoline skeleton found in several bioactive molecules. For example, tivantinib (Figure 1, middle) exhibits MET inhibitor properties [1]; whereas tarazepide (Figure 1, right) is being

• of β-arylated 5,6-dihydropyrrolo[3,2,1-ij]quinoline derivatives [6] (Scheme 1a). Three α-arylated 5,6-dihydropyrrolo[3,2,1-ij]quinoline derivatives have been prepared by Pal et al. via the cyclization of 8-arylethynyl-1,2,3,4-tetrahydroquinolines [9] (Scheme 1b). The best results were obtained using

• 38% yield; whereas the use of 2-chlorobenzonitrile afforded 12 in 62% regioselectivity and in 34% yield. In both cases, partial conversions of the aryl chlorides were observed. Pyridines and quinoline heterocycles are very important structures in pharmaceutical chemistry as more than 100 currently

1,2,3,4-Tetrahydro-1,4,5,8-tetraazaanthracene revisited: properties and structural evidence of aromaticity loss

• Arnault Heynderickx,
• Sébastien Nénon,
• Olivier Siri,
• Vladimir Lokshin and
• Vladimir Khodorkovsky

Beilstein J. Org. Chem. 2019, 15, 2059–2068, doi:10.3762/bjoc.15.203

• the formation of hydrogen bonds, an approach known as ‘crystal engineering’ (see, for instance, [13][14] and references therein). Indeed, whereas several two-component molecular systems cocrystallizing in a special layered way involving pyrazine, quinoline and phenazine as the H-bond acceptor and

• kcal/mol. For comparison, we calculated the proton affinities of quinoline: 217.0 and 4-dimethylaminopyridine: 240.1 kcal/mol at the same level of theory (the experimental values for these two derivatives are 214.4 and 235.7 kcal/mol, respectively [25]). Thus, the basicity of 3 is close to that of 4

Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

• Gagandeep Kour Reen,
• Ashok Kumar and
• Pratibha Sharma

Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165

• carbonate as a base under aerobic conditions. Along with the synthesis of pyrido[1,2-a]benzimidazoles 78, they have reported the synthesis of benzimidazo[1,2-a]quinoline 79 and benzimidazo[1,2-a]isoquinoline 80 in good to excellent yields. They have used differently substituted arylboronic acids 77 as one

Synthesis of ([1,2,4]triazolo[4,3-a]pyridin-3-ylmethyl)phosphonates and their benzo derivatives via 5-exo-dig cyclization

• Aleksandr S. Krylov,
• Artem A. Petrosian,
• Julia L. Piterskaya,
• Nataly I. Svintsitskaya and
• Albina V. Dogadina

Beilstein J. Org. Chem. 2019, 15, 1563–1568, doi:10.3762/bjoc.15.159

• the phosphoryl unit resonating at 3.75–4.19 ppm with 2JHP = 20 Hz. At lower field, the signals of 6 protons of the (iso)quinoline rings are present at 7.1–8.7 ppm. In the 13C NMR spectra, the methylene and methine carbons of the triazole ring resonate as doublet signals with characteristic constants

Synthesis of pyrrolo[1,2-a]quinolines by formal 1,3-dipolar cycloaddition reactions of quinolinium salts

• Anthony Choi,
• Rebecca M. Morley and
• Iain Coldham

Beilstein J. Org. Chem. 2019, 15, 1480–1484, doi:10.3762/bjoc.15.149

• Anthony Choi Rebecca M. Morley Iain Coldham Department of Chemistry, University of Sheffield, Brook Hill, Sheffield, S3 7HF, UK 10.3762/bjoc.15.149 Abstract Quinolinium salts, Q+-CH2-CO2Me Br− and Q+-CH2-CONMe2 Br− (where Q = quinoline), were prepared from quinolines. Deprotonation of these salts

• with a quinoline. Pyrroloquinolines have been found to show antibacterial and antifungal activity, to be ligands for the NK1 receptor, and to be effective against the Hif hypoxia pathway in cancer cell lines [36][37][38]. Almost all of the examples of dipolar cycloaddition reactions involving

• reaction of quinolinium salts bearing electron-withdrawing groups other than ketones, we prepared ester 4 [55] and amide 5 by alkylation of quinoline. Arylidenemalononitriles such as 6a are known to undergo related chemistry [41], so we heated this compound with the quinolinium salts in the presence of

Multicomponent reactions (MCRs): a useful access to the synthesis of benzo-fused γ-lactams

• Edorta Martínez de Marigorta,
• Jesús M. de Los Santos,
• Ana M. Ochoa de Retana,
• Javier Vicario and
• Francisco Palacios

Beilstein J. Org. Chem. 2019, 15, 1065–1085, doi:10.3762/bjoc.15.104

• . Another aromatic aldehyde, in this case derived from a quinoline, can also be used as substrate for a multicomponent reaction, appropriate for the preparation of 3-aminoisoindolinone analogues 98 (Scheme 28) [106]. Indeed, the reaction of chloroquinolinecarbaldehydes 97 with isocyanides 42 and aromatic

• amines 2, catalysed by Pd, produced a small collection (8 examples, 75–95% yield) of quinoline derivatives 98 containing a γ-lactam moiety with different substituents at the nitrogen of the 5-membered ring and in the γ-position. Although the authors do not suggest a mechanism, this probably starts with

New α- and β-cyclodextrin derivatives with cinchona alkaloids used in asymmetric organocatalytic reactions

• Iveta Chena Tichá,
• Simona Hybelbauerová and
• Jindřich Jindřich

Beilstein J. Org. Chem. 2019, 15, 830–839, doi:10.3762/bjoc.15.80

• with monosubstituted derivatives at position 6 on the primary rim (Figure 3). Generally, we observed four different regions with the typical signals: the first, well-resolved aromatic region belongs to the quinoline part of the cinchona alkaloid (9.00–7.55 ppm) and to the hydrogen signal of the

Catalyst-free assembly of giant tris(heteroaryl)methanes: synthesis of novel pharmacophoric triads and model sterically crowded tris(heteroaryl/aryl)methyl cation salts

• Rodrigo Abonia,
• Luisa F. Gutiérrez,
• Braulio Insuasty,
• Jairo Quiroga,
• Kenneth K. Laali,
• Chunqing Zhao,
• Gabriela L. Borosky,
• Samantha M. Horwitz and
• Scott D. Bunge

Beilstein J. Org. Chem. 2019, 15, 642–654, doi:10.3762/bjoc.15.60

• State University, Kent, OH 44242, USA 10.3762/bjoc.15.60 Abstract A series of giant tris(heteroaryl)methanes are easily assembled by one-pot three-component synthesis by simple reflux in ethanol without catalyst or additives. Diversely substituted indoles (Ar1) react with quinoline aldehydes, quinolone

• new structure. This concept has recently received attention by the pharmaceutical industry because it provides new options to develop more specific drugs for the treatment of persistent and challenging pathologies [27][28] (Scheme 1). The indole, coumarin, quinoline, chromone and fluorene moieties are

• the indole and coumarin partners also characterizes these approaches, Scheme 2. Continuing our current program on the synthesis of quinoline-based heterocyclic compounds of biological interest [54][55][56][57], we describe here a Yonemitsu-based direct and reproducible three-component synthesis of

Oxidative radical ring-opening/cyclization of cyclopropane derivatives

• Yu Liu,
• Qiao-Lin Wang,
• Zan Chen,
• Cong-Shan Zhou,
• Bi-Quan Xiong,
• Pan-Liang Zhang,
• Chang-An Yang and
• Quan Zhou

Beilstein J. Org. Chem. 2019, 15, 256–278, doi:10.3762/bjoc.15.23

• transformation. In 2017, Reddy and co-workers reported the first radical cyclization of propiolamides (131 and 133) with cyclopropanols 91 for the synthesis of azaspiro[4.5]deca-3,6,9-triene-2,8-diones 132 and 6,7-dihydro-3H-pyrrolo[2,1-j]quinoline-3,9(5H)-diones 134 (Scheme 35) [115]. Interestingly, this

An overview on recent advances in the synthesis of sulfonated organic materials, sulfonated silica materials, and sulfonated carbon materials and their catalytic applications in chemical processes

• Hashem Sharghi,
• Pezhman Shiri and
• Mahdi Aberi

Beilstein J. Org. Chem. 2018, 14, 2745–2770, doi:10.3762/bjoc.14.253

• these catalysts for extensive reactions, including the synthesis of bis(indolyl)methane derivatives, β-amino carbonyl compounds, 14H-dibenzo[a,j]xanthene derivatives, 1,8-dioxodecahydroacridine derivatives, xanthene derivatives, pyrimido[4,5-b]quinoline derivatives, spiro-isatin derivatives, spiro

• -acenaphthenequinone derivatives, tetrahydrobenzo[a]xanthenone derivatives, tetrahydrobenzo[a]acridinone derivatives, 1-amidoalkyl-2-naphthol derivatives, 2H-indazolo[2,1-b]phthalazine-1,6,11(13H)trione derivatives, quinoline derivatives, bis-coumarin derivatives, 2H-indazolo[2,1-b]phthalazinetrione derivatives

• . [Dsim]HSO4 (26) has been also employed as a reusable and efficient catalyst for the one-pot multicomponent synthesis of various xanthene derivatives 24, 27, and 28 and pyrimido[4,5-b]quinoline derivatives 30 under mild and green conditions (Scheme 4) [42][43][44]. Easy preparation of the catalyst, easy