Iron-catalyzed domino coupling reactions of π-systems

• Austin Pounder and
• William Tam

Beilstein J. Org. Chem. 2021, 17, 2848–2893, doi:10.3762/bjoc.17.196

• would give the oxindole scaffold. Hydrogen abstraction would regenerate the reduced iron catalyst and produce the final product. Two years later, Zhou and co-workers expanded the reaction for the synthesis of substituted isoquinoline-1,3(2H,4H)-dione derivatives 64 (Scheme 10) [81]. Both laboratories

• FeCl2-catalyzed carbochloromethylation of activated alkenes 60 (Scheme 28) [121]. The reaction was amenable to a range of commercially available chlorinated methane units 139; however, CH2Cl2 and CCl4 (139a) performed the best and delivered the oxindole products 140 in good to excellent yield. The

Recent advances in the asymmetric phosphoric acid-catalyzed synthesis of axially chiral compounds

• Alemayehu Gashaw Woldegiorgis and
• Xufeng Lin

Beilstein J. Org. Chem. 2021, 17, 2729–2764, doi:10.3762/bjoc.17.185

• this regard, Shi and co-workers reported the first atroposelective access to oxindole-based axial chiral styrenes or vinylarenes by kinetic resolution of racemic oxindole-based styrenes 83 and azalactones 84. In the presence of CPA 20, racemic oxindole-based styrenes reacted with azalactones via

• hydrogen bonding, and the azalactones underwent asymmetric ring opening to form axially chiral oxindole-based styrenes 85 in up to 53% yield with good diastereoselectivities (up to 94:6 dr) and enatioselectivities (up to 95% ee). Moreover, the racemic oxindole-based styrenes underwent kinetic resolution to

• afford other axially chiral styrenes 86 in moderate yields (up to 54%) with excellent enantioselectivities (up to 96% ee) and high selectivity factors (SF up to 106) [92]. This strategy is critical for accessing axially chiral the oxindole-based styrenes and provides a robust method for the synthesis of

A novel methodology for the efficient synthesis of 3-monohalooxindoles by acidolysis of 3-phosphate-substituted oxindoles with haloid acids

• Li Liu,
• Yue Li,
• Tiao Huang,
• Dulin Kong and
• Mingshu Wu

Beilstein J. Org. Chem. 2021, 17, 2321–2328, doi:10.3762/bjoc.17.150

• -substituted oxindole intermediates and SN1 reactions with haloid acids. This new procedure features mild reaction conditions, simple operation, good yield, readily available and inexpensive starting materials, and gram-scalability. Keywords: acidolysis; haloid acids; isatin; 3-monohalooxindole; 3-phosphate

• , 3-monohalooxindoles have emerged as a class of versatile building blocks for the construction of various 3,3-disubstituted oxindole and spirooxindole derivatives, such as spirocyclopropaneoxindoles [3][4][5][6][7][8][9][10][11], 3-β-amino-substituted 3-halooxindoles [12][13][14], five-membered-ring

• challenge in chemistry. In order to achieve this goal, and on the basis of our previous experiences in the functionalization of oxindoles [33][34], we herein designed a nucleophilic substitution method of an isatin-derived 3-phosphate-substituted oxindole with haloid acids, leading to 3-monohalooxindoles

Base-free enantioselective S_N2 alkylation of 2-oxindoles via bifunctional phase-transfer catalysis

• Mili Litvajova,
• Emiliano Sorrentino,
• Brendan Twamley and
• Stephen J. Connon

Beilstein J. Org. Chem. 2021, 17, 2287–2294, doi:10.3762/bjoc.17.146

• Mili Litvajova Emiliano Sorrentino Brendan Twamley Stephen J. Connon School of Chemistry, Trinity Biomedical Sciences Institute, Trinity College Dublin, 152-160 Pearse Street, Dublin 2, Ireland 10.3762/bjoc.17.146 Abstract N-Protected oxindole derivatives of unprecedented malleability bearing

• synthesis of a potent CRTH2 receptor antagonist. Keywords: alkylation; base-free; cinchona alkaloids; CRTH2 antagonist; hydrogen-bonding; oxindole; phase-transfer catalysis; Introduction The 2-oxindole scaffold is an important motif present in a myriad of natural products. Among 2-oxidole derivatives, 3,3

• charged intermediates, could be an excellent methodology for the enantioselective SN2 alkylation of enolates derived from the 2-oxindole core [13][14][15][16][17][18][19][20][21][22][23]. In recent years, several examples regarding the alkylation of 3-subsituted-2-oxindoles, via asymmetric phase-transfer

A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries

• Guido Gambacorta,
• James S. Sharley and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2021, 17, 1181–1312, doi:10.3762/bjoc.17.90

Heterogeneous photocatalytic cyanomethylarylation of alkenes with acetonitrile: synthesis of diverse nitrogenous heterocyclic compounds

• Guanglong Pan,
• Qian Yang,
• Wentao Wang,
• Yurong Tang and
• Yunfei Cai

Beilstein J. Org. Chem. 2021, 17, 1171–1180, doi:10.3762/bjoc.17.89

• the construction of valuable oxindole and isoquinolinedione derivatives. With respect to the generality of the N-aryl acrylamides 7 (Scheme 4), a range of frequently encountered functional groups were well tolerated affording the methoxy (8b), methyl (8c), the halogenated (8d–f), trifluromethyl (8g

• loss of photocatalytic activity when applied in the cyanomethylarylation of N-arylallylamine 1a with acetonitrile. We also utilized this strategy to test n-butyl nitrile under the standard conditions. As shown in Scheme 6a, the corresponding oxindole 11 was obtained in 45% yield. The synthetic utility

• was further demonstrated by a series of successful derivatizations of the cyano-substituted oxindole 8a. For instance, after the Ritter reaction, 8a was smoothly converted to N-tert-butylated acetamide 12 in 96% yield (Scheme 6b). A modified Witte–Seeliger reaction led to the formation of oxazoline 13

N-tert-Butanesulfinyl imines in the asymmetric synthesis of nitrogen-containing heterocycles

• Joseane A. Mendes,
• Paulo R. R. Costa,
• Miguel Yus,
• Francisco Foubelo and
• Camilla D. Buarque

Beilstein J. Org. Chem. 2021, 17, 1096–1140, doi:10.3762/bjoc.17.86

Synthetic reactions driven by electron-donor–acceptor (EDA) complexes

• Zhonglie Yang,
• Yutong Liu,
• Kun Cao,
• Xiaobin Zhang,
• Hezhong Jiang and
• Jiahong Li

Beilstein J. Org. Chem. 2021, 17, 771–799, doi:10.3762/bjoc.17.67

• the EDA complex formed by aryl halide 106 and oxindole 107 under alkaline conditions allowed single-electron transfer under irradiation with light, eventually affording arylated oxidized indole product 108 (Scheme 37). This reaction provides an effective method to construct various 3-arylindoles with

Synthesis of (Z)-3-[amino(phenyl)methylidene]-1,3-dihydro-2H-indol-2-ones using an Eschenmoser coupling reaction

• Lukáš Marek,
• Lukáš Kolman,
• Jiří Váňa,
• Jan Svoboda and
• Jiří Hanusek

Beilstein J. Org. Chem. 2021, 17, 527–539, doi:10.3762/bjoc.17.47

• of the oxindole skeleton were also described starting from 2-alkynylphenyl isocyanates and their precursors [21][22][23], or from N-phenylpropiolamides [24][25][26]. The newest method of synthesis, starting from 3-bromo-3-[bromo(phenyl)methyl]oxindole and substituted anilines [27], is similar to a

• we recently discovered [32][33] a new synthetic pathway involving a rearrangement of 2-aryl-5-(2-aminophenyl)-4-hydroxy-1,3-thiazoles (e.g., 8aa–ad in Scheme 2) leading to the 3-[amino(aryl)methylidene]-1,3-dihydro-2H-indol-2-ones containing an unsubstituted amino group and the oxindole nucleus. In

• desired Eschenmoser coupling reaction (route b). Therefore, the nucleophilicity of the conjugated base of the nitrogen (benzenecarbimidothioate or thioimidate) is exerted towards the oxindole carbonyl to give the thiazole. Moreover, if both benzene rings contain electron-withdrawing groups, enhancing

All-carbon [3 + 2] cycloaddition in natural product synthesis

• Zhuo Wang and
• Junyang Liu

Beilstein J. Org. Chem. 2020, 16, 3015–3031, doi:10.3762/bjoc.16.251

• fragmentation to afford alkene 72 in 61% yield. Marcfortine B (8) was synthesized from alkene 72 in seven steps. The enantioselective synthesis of marcfortine C (9) commenced with a catalytic asymmetric cyano-substituted TMM cycloaddition of oxindole 73 and TMM donor 75 with Pd(dba)2/74 as catalyst to give a

• rationalized by the proposed catalytic mechanism (Scheme 7B). The phosphine (i.e., PR3, A) attacks the allene 101 to generate zwitterion intermediate B, which is subjected to a less hindered attack by the isoindigo 100. The oxindole bearing a chlorine atom on isoindigo 100 makes C-3 more electron deficient

Bifurcated synthesis of methylene-lactone- and methylene-lactam-fused spirolactams via electrophilic amide allylation of γ-phenylthio-functionalized γ-lactams

• Tetsuya Sengoku,
• Koki Makino,
• Ayumi Iijima,
• Toshiyasu Inuzuka and
• Hidemi Yoda

Beilstein J. Org. Chem. 2020, 16, 2769–2775, doi:10.3762/bjoc.16.227

• -lactone derivatives spiro-fused to an oxindole (A), one of which exhibited a potent cytotoxic activity [9]. Our research group succeeded the enantiopure synthesis of these compounds, in which enantioselective allylation of an isatin derivative with an amido-functionalized allylstannane was employed as a

• methylene-lactams (C) through zinc-catalyzed addition to N-carbonyl imides [13][14][16]. Meanwhile, we also developed an umpolung electrophilic allylation of 3-heterosubstituted oxindole D for the synthesis of lactam analog of A (Scheme 1c) [17]. The oxindole D readily reacted with 2-(acetoxy)methyl

• acrylamides 1 in the presence of a catalytic amount of Pd(PPh3)4 to give the corresponding adducts which could be delivered into an methylene-lactam-fused oxindole. On the basis of this umpolung strategy, spirolactams 4 and 5, which are N-alkyl or N-phenyl-substituted analogs of B and C and unable to be

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

• discovered. Similarly, the 2-oxindole framework is prevalent in a wide range of natural products [10]. For example, convolutamydines [11] are alkaloids containing a dibromohydroxyoxindole moiety, isolated from the Floridian bryozoan Amathia convulata, while coerulescine [12] is an oxindole alkaloid isolated

• , that shows antimalarial activity [40] and satavaptan, a selective V2-receptor antagonist that is useful for the treatment of cirrhosis (Figure 5) [41][42]. Additionally, methisazone is a 2-oxindole derivative that has been used as antiviral drug, especially for the prophylactic treatment of small-pox

• ]. Besides, several hybrid molecules containing, inter alia the oxindole moiety, have been discovered and they demonstrated diverse therapeutic activities, for example, against breast [46] and colon cancer cells [47] and drug-resistant bacteria [48]. Among the many excellent recent reviews on the preparation

Novel (2-amino-4-arylimidazolyl)propanoic acids and pyrrolo[1,2-c]imidazoles via the domino reactions of 2-amino-4-arylimidazoles with carbonyl and methylene active compounds

• Victoria V. Lipson,
• Tetiana L. Pavlovska,
• Nataliya V. Svetlichnaya,
• Anna A. Poryvai,
• Nikolay Yu. Gorobets,
• Erik V. Van der Eycken,
• Irina S. Konovalova,
• Svetlana V. Shiskina,
• Alexander V. Borisov,
• Vladimir I. Musatov and
• Alexander V. Mazepa

Beilstein J. Org. Chem. 2019, 15, 1032–1045, doi:10.3762/bjoc.15.101

• oxindole moiety, and the resulting structures can be considered as analogues of 3,3'-spiroxindole alkaloids, such as spirotryprostatin B (17, Figure 6) [37]. Indeed, the equimolar three-component reactions with the participation of 2-amino-4-arylimidazoles 1, isatins 18 and acyclic methylene active

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

• -sulfo-1,4-diazabicyclo[2.2.2]octane-1,4-diium) chloride (C4(DABCO-SO3H)2·4Cl, 31) and its applications in the synthesis of spiro-oxindole derivatives 36 and 37 was described. C4(DABCO-SO3H)2·4Cl 31 acted as an efficient, cheap, and reusable nanocatalyst for synthesis of 2-amino-4H-pyran derivatives 36

Recent advances in hypervalent iodine(III)-catalyzed functionalization of alkenes

• Xiang Li,
• Pinhong Chen and
• Guosheng Liu

Beilstein J. Org. Chem. 2018, 14, 1813–1825, doi:10.3762/bjoc.14.154

• -disubstituted-α-hydroxy-carboxylamides, was disclosed by Gulder and co-workers [76]. This catalytic system was applied to the bromination of alkenes by Gulder and co-workers. For example, the iodine(III)-catalyzed halocyclization of methacrylamide 68 generated the brominated oxindole 69 (Scheme 20) [77]. In

Synthesis of chiral 3-substituted 3-amino-2-oxindoles through enantioselective catalytic nucleophilic additions to isatin imines

• Hélène Pellissier

Beilstein J. Org. Chem. 2018, 14, 1349–1369, doi:10.3762/bjoc.14.114

• -bromo-substituted derivative (R2 = 5-Br) which afforded the corresponding product in only 41% ee. An advantage of this methodology was the use of a very low catalyst loading (1 mol %). Earlier in 2016, Silvani and Lesma described the synthesis of chiral 3-amino-2-oxindole butenolides 11 on the basis of

• good yields (78–81%) while the presence of a halogen substituent on the oxindole moiety (R2 = 5-F, 5-Cl, 6-Br) resulted in a lowering of both yields (42–68%) and enantioselectivities (15–74% ee). In 2017, Shao et al. investigated the use of simple chiral primary amines to promote the enantioselective

• catalytic asymmetric construction of the cyclic enaminone-based 3-substituted 3-amino-2-oxindole scaffold with potential bioactivity on the basis of enantioselective additions of cyclic enaminones to N-Boc-isatin imines [40]. As shown in Scheme 7, the addition of dimedone-derived enaminones 22 to a variety

Methyl isocyanide as a convertible functional group for the synthesis of spirocyclic oxindole γ-lactams via post-Ugi-4CR/transamidation/cyclization in a one-pot, three-step sequence

• Amarendar Reddy Maddirala and
• Peter R. Andreana

Beilstein J. Org. Chem. 2018, 14, 875–883, doi:10.3762/bjoc.14.74

• ]. Significant efforts have been made to design creative synthetic strategies for spirocyclic oxindole molecules, of which, isatin-based domino reactions [24][25][26][27][28][29][30] have proved to be very versatile [31] and readily achievable [32][33][34][35][36][37]. However, finding a simple and efficient

• spirocyclic oxindole γ-lactams). There have been other groups in the past, including our own research group, who have reported on post-modified Ugi-four-component synthetic strategies (Scheme 1) towards the synthesis of 2-oxindoles and spiro[indoline-3,2'-pyrrole]-2,5'(1'H)-diones and spiro[indoline-3,2

• facile to synthesize. Here within, we document that the reaction sequence for spirocyclic oxindole γ-lactams (Scheme 2) follows a three-step sequential strategy involving: a) an Ugi-4CR, b) an acid-promoted intramolecular transamidation, and c) a base-mediated cyclization giving spiro[indoline-3,2

CF₃SO₂X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation and chlorination. Part 2: Use of CF₃SO₂Cl

• Hélène Chachignon,
• Hélène Guyon and
• Dominique Cahard

Beilstein J. Org. Chem. 2017, 13, 2800–2818, doi:10.3762/bjoc.13.273

• . However, the scope of application was extended to substrates carrying more diverse R2 groups such as ethers, esters or alcohols. In 2015, Yang, Xia and co-workers reported that trifluoromethylated oxindole derivatives could also be accessed from N-tosylacrylamides 5, via a similar pathway including an

• amide. On the other hand, for N-alkylacrylamides, intermediate 8 preferentially cyclised to yield intermediate 9, which ultimately gave access to the oxindole derivative product. Yang, Xia and co-workers were also interested in structurally close substrates that are N-methacryloyl-N-methylbenzamide

• silyl enol ethers. Continuous flow trifluoromethylation of ketones under photoredox catalysis. Trifluoromethylation of enol acetates. Photoredox-catalysed tandem trifluoromethylation/cyclisation of N-arylacrylamides: a route to trifluoromethylated oxindole derivatives. Tandem trifluoromethylation

CF₃SO₂X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation. Part 1: Use of CF₃SO₂Na

• Hélène Guyon,
• Hélène Chachignon and
• Dominique Cahard

Beilstein J. Org. Chem. 2017, 13, 2764–2799, doi:10.3762/bjoc.13.272

• carbotrifluoromethylation of N-arylacrylamides 46 with CF3SO2Na to produce oxindoles 47 [45]. Addition of the CF3 radical to such an electron-deficient alkene should be unfavourable. However, the subsequent annulation step drove the cascade process toward oxindole synthesis. The reaction utilised Langlois’ conditions with

• 49. Finally, oxidation of 49 by Cu(n + 1) and aromatisation afforded the oxindole and regenerated the copper catalyst (Scheme 25). The same indoles bearing a 2,2,2-trifluoroethyl side-chain were also obtained in reactions performed with CF3SO2Na and (NH4)2S2O8 as the oxidant in the presence of a

• into the final oxindole (Scheme 26). In an independent work Wang and co-workers demonstrated that silver nitrate was not necessary for the reaction to proceed in acetonitrile and water at 80 °C (Scheme 27) [48]. Again, N-acyl and N–H derivatives failed to deliver the desired products and meta

Construction of highly enantioenriched spirocyclopentaneoxindoles containing four consecutive stereocenters via thiourea-catalyzed asymmetric Michael–Henry cascade reactions

• Yonglei Du,
• Jian Li,
• Kerong Chen,
• Chenglin Wu,
• Yu Zhou and
• Hong Liu

Beilstein J. Org. Chem. 2017, 13, 1342–1349, doi:10.3762/bjoc.13.131

• spirocyclopentaneoxindoles. Keywords: asymmetric synthesis; four consecutive stereocenters; Michael–Henry cascade reactions; spirocyclopentaneoxindoles; thioureas; Introduction The spirocyclic oxindole core represents an important scaffold that is encountered frequently in many biologically active molecules and natural

• to 94%) (Scheme 1, reaction 1D). Results and Discussion To establish the optimal experimental conditions for the synthesis of spirocyclopentaneoxindoles, we chose 3-substituted oxindole 1a and nitrovinylacetamide (2a) as the model substrates, and the results are summarized in Table 1. Initially, a

• , respectively (Table 1, entries 1 and 2). Further experiments showed that a bifunctional thiourea catalyst d was the most efficient for the synthesis of spirocyclic oxindole derivatives in good yields (80%) with excellent diastereoselectivity (8:92 dr), and moderate enantioselectivity (83% ee, Table 1, entries

An effective one-pot access to polynuclear dispiroheterocyclic structures comprising pyrrolidinyloxindole and imidazothiazolotriazine moieties via a 1,3-dipolar cycloaddition strategy

• Alexei N. Izmest’ev,
• Galina A. Gazieva,
• Natalya V. Sigay,
• Sergei A. Serkov,
• Valentina A. Karnoukhova,
• Vadim V. Kachala,
• Alexander S. Shashkov,
• Igor E. Zanin,
• Angelina N. Kravchenko and
• Nina N. Makhova

Beilstein J. Org. Chem. 2016, 12, 2240–2249, doi:10.3762/bjoc.12.216

• the synthesis of dispiro compounds comprising pyrrolidine, oxindole, and other heterocycle moieties and to the evaluation of their physiological properties [24][26][27][28][29][30][31][32]. In this regard, our attention was directed towards hetero-annelated 1,2,4-triazines, because this motif is part

• of these two bands, one broad band is observed), and 1649–1634 cm−1 that are characteristic of oxindole, imidazolidinone, and thiazolidinone ring carbonyl groups. The 1H NMR spectra of compounds 4 exhibited, along with the proton signals of the imidazothiazolotriazine and oxindole moieties, the

Chiral ammonium betaine-catalyzed asymmetric Mannich-type reaction of oxindoles

• Masahiro Torii,
• Kohsuke Kato,
• Daisuke Uraguchi and
• Takashi Ooi

Beilstein J. Org. Chem. 2016, 12, 2099–2103, doi:10.3762/bjoc.12.199

• quaternary and tertiary stereogenic carbon centers on biologically intriguing molecular frameworks with high fidelity. Keywords: ammonium betaine; asymmetric catalysis; Mannich reaction; organocatalysis; oxindole; Introduction Chiral indole alkaloids possessing C-3 quaternary indoline frameworks are an

• straightforward method for accessing a wide array of chiral indoline skeletons [5][6][7][8]. The most common strategy in this approach is to utilize an oxindole enolate as a nucleophile, because facile deprotonation from the C-3 carbon is ensured by the inductive effect of the α-carbonyl group and by the enolate

• stability arising from the aromatic character. Accordingly, a number of catalytic methods are available for the asymmetric functionalization of oxindole enolates with various different electrophiles. However, successful examples of Mannich-type reactions with imines are surprisingly limited despite allowing

Enantioconvergent catalysis

• Justin T. Mohr,
• Jared T. Moore and
• Brian M. Stoltz

Beilstein J. Org. Chem. 2016, 12, 2038–2045, doi:10.3762/bjoc.12.192

• . Additionally, there must be a significant difference in the rates of product formation (i.e. k3 > k4). If this condition is not met, enantioselectivity will suffer. Stoltz and co-workers have reported an approach for the preparation of enantioenriched oxindole derivatives from racemic oxindole halides using a

• stereoablative approach (Scheme 3) [22][23]. Deprotonation and elimination of the halide in oxindole (±)-8 leads to achiral azaxylylene intermediate 11, which is trapped with malonate nucleophiles to form all-carbon quaternary centers. The overall transformation is unusual since oxindoles are typically

• nucleophilic, but in this case the stereoablative step in the mechanism leads to an electrophilic intermediate. The use of Cu(box) complex 9 rendered the reaction enantioselective, forming C-3 quaternary oxindole 12 in 91% ee (up to 94% ee for related substrates). This strategy is useful for constructing spiro

Enantioselective addition of diphenyl phosphonate to ketimines derived from isatins catalyzed by binaphthyl-modified organocatalysts

• Hee Seung Jang,
• Yubin Kim and
• Dae Young Kim

Beilstein J. Org. Chem. 2016, 12, 1551–1556, doi:10.3762/bjoc.12.149

• isatins has been achieved. This method affords practical and efficient access to chiral 3-amino-3-phosphonyl-substituted oxindole derivatives in high yields with excellent enantioselectivities (up to 99% ee). Keywords: 3-amino-3-phosphonyl-substituted oxindole; α-aminophosphonates; bifunctional

• attention, and numerous catalytic enantioselective methods using chiral catalysts have been reported [9][10][11][12][13]. Oxindole and its derivatives can be exploited as important synthons to synthesize various alkaloid natural products and biologically active compounds [14][15][16]. In particular, 3,3

• -disubstituted oxindoles bearing a quaternary stereogenic center at the C3-position have been reported to be biologically active against a variety of targets [17][18][19]. Consequently, the asymmetric synthesis of 3,3-disubstituted oxindole derivatives has received significant research attention over the past

Synthesis of 2-oxindoles via 'transition-metal-free' intramolecular dehydrogenative coupling (IDC) of sp² C–H and sp³ C–H bonds

• Nivesh Kumar,
• Santanu Ghosh,
• Subhajit Bhunia and
• Alakesh Bisai

Beilstein J. Org. Chem. 2016, 12, 1153–1169, doi:10.3762/bjoc.12.111

• -carbon quaternary center at the pseudo benzylic position has been achieved via a ‘transition-metal-free’ intramolecular dehydrogenative coupling (IDC). The construction of 2-oxindole moieties was carried out through formation of carbon–carbon bonds using KOt-Bu-catalyzed one pot C-alkylation of β-N

• spectrum of biological and pharmacological properties and hence are very attractive as well as challenging synthetic targets [26]. Selected examples for the synthesis of 2-oxindole include an intramolecular homolytic aromatic substitution on the aryl ring by an amidyl radical formed by homolysis of a C–X

• engaged in the development of efficient methodologies for the synthesis of 2-oxindoles with intriguing ring systems. To this end, recently, we have reported a transition-metal-free ‘intramolecular-dehydrogenative-coupling' (IDC) strategy to access such 2-oxindole moieties through a C-alkylation followed