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

• important class of biologically relevant molecules, and numerous efforts have been made for the development of reliable synthetic methodologies to enable the installation of the C-3 stereogenic center [1][2][3][4]. Among them, the direct stereoselective functionalization of 3-monosubstituted oxindoles is a

• efficient construction of vicinal quaternary and tertiary stereocenters [9][10][11][12][13][14][15][16][17][18][19][20][21][22]. In particular, the application of 3-aryl substituted oxindoles seems problematic; hence, the full potential of this useful carbon–carbon bond formation is yet to be realized [12

• properties of both oxindoles 2 and N-Boc aldimines 3, but reactivity and diastereoselectivity sometimes fluctuated depending on the structure of these substrates. While significant variation in the imine substituents was feasible, the introduction of electron-withdrawing groups at the meta-position slightly

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

• 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

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

• -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

• few decades [20][21][22]. General approaches for the synthesis of chiral 3-substituted-3-aminooxindole derivatives include the amination of various 3-monosubstituted oxindoles [23][24][25][26][27] and the nucleophilic addition to ketimines derived from isatin derivatives [28][29][30][31][32][33][34

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

• Nivesh Kumar Santanu Ghosh Subhajit Bhunia Alakesh Bisai Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal Bypass Road, Bhauri, Bhopal – 462 066, Madhya Pradesh, India 10.3762/bjoc.12.111 Abstract The synthesis of a variety of 2-oxindoles bearing an all

• -arylamido esters with alkyl halides followed by a dehydrogenative coupling. Experimental evidences indicated toward a radical-mediated path for this reaction. Keywords: C−H functionalization; intramolecular dehydrogenative coupling (IDC); iodine; N-iodosuccinimide; oxidants; 2-oxindoles; Introduction The

• recently gained immense importance. 2-Oxindoles having all carbon quaternary centres at the pseudobenzylic position are common structural scaffolds in many naturally occurring alkaloids of biological relevance [22][23][24][25]. These heterocyclic motifs especially exist in indole alkaloids with a wide

Catalytic asymmetric synthesis of biologically important 3-hydroxyoxindoles: an update

• Bin Yu,
• Hui Xing,
• De-Quan Yu and
• Hong-Min Liu

Beilstein J. Org. Chem. 2016, 12, 1000–1039, doi:10.3762/bjoc.12.98

• -substituted 3-hydroxyoxindoles and 3-hydroxyoxindole-based further transformations. Keywords: 3-hydroxyoxindoles; oxindoles; organocatalysis; spirooxindoles; transition metal catalysis; Introduction Chiral oxindoles are an important class of compounds, which widely exist in nature and have exhibited diverse

• Recently, iridium has emerged as a powerful catalyst for C–H bond functionalization [20][21][22][23]. In 2014, Yamamoto and co-workers reported a cationic iridium complex catalyzed asymmetric intramolecular hydroarylation of α-ketoamides, yielding 3-substituted 3-hydroxy-2-oxindoles with high

• reactions of α-olefins and styrenes with 3-hydroxy-2-oxindoles were achieved by using the ruthenium complex, giving the products as single diastereoisomers (Scheme 11) [27]. Interestingly, 1-adamantanecarboxylic acid (10 mol %) as a co-catalyst can remarkably enhance the yields from trace to >90%. A broad

1H-Imidazol-4(5H)-ones and thiazol-4(5H)-ones as emerging pronucleophiles in asymmetric catalysis

• Antonia Mielgo and
• Claudio Palomo

Beilstein J. Org. Chem. 2016, 12, 918–936, doi:10.3762/bjoc.12.90

• substrate; however, to date, the carbonyl components for these reactions are mostly restricted to 1,3-diones, β-ketoesters, malonates, α-cyanoacetates, 3-substitued oxindoles and related systems. Generally, enolizable esters or carboxylic acid derivatives have been challenging in this strategy, because

• published [73]. This study shows that α’-oxyenones are very efficient key enoate equivalents in Brønsted base-catalyzed asymmetric conjugate addition of a range of soft nucleophiles such as α-substituted oxindoles, cyanoesters, oxazolones, azlactones and thiazolones to afford the corresponding

• γ-additions until the group of Lu published in 2014 the addition of 3-substitued oxindoles [111]. More recently, Lu together with Lan also demonstrated the efficiency of oxazol-4(5H)-ones and thiazol-4(5H)-ones as pronucleophiles in the highly enantioselective phosphine-catalyzed asymmetric γ

Asymmetric α-amination of 3-substituted oxindoles using chiral bifunctional phosphine catalysts

• Qiao-Wen Jin,
• Zhuo Chai,
• You-Ming Huang,
• Gang Zou and
• Gang Zhao

Beilstein J. Org. Chem. 2016, 12, 725–731, doi:10.3762/bjoc.12.72

• , Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, People’s Republic of China 10.3762/bjoc.12.72 Abstract A highly enantioselective α-amination of 3-substituted oxindoles with azodicarboxylates catalyzed by amino acids-derived chiral phosphine

• stereogenic carbon centers; Introduction Recently, chiral 3-substituted oxindoles have been attractive targets in asymmetric synthesis due to their abundance in the structures of numerous natural products and pharmaceutically active compounds [1]. In particular, the chiral 3-aminooxindoles containing a

• organocatalysis and metal catalysis for the construction of this type of structures. For example, Chen et al. reported the first organocatalytic enantioselective amination reaction of 2-oxindoles catalyzed by biscinchona alkaloid catalysts [8]. Zhou [9][10] and Barbas [11][12], have independently reported similar

The aminoindanol core as a key scaffold in bifunctional organocatalysts

• Isaac G. Sonsona,
• Eugenia Marqués-López and
• Raquel P. Herrera

Beilstein J. Org. Chem. 2016, 12, 505–523, doi:10.3762/bjoc.12.50

• scalable asymmetric Michael addition of 3-substituted oxindoles 39 to the protected 2-amino-1-nitroethenes 40, using the bifunctional tertiary amine aminoindanol-based organocatalyst 41 (Scheme 14) [44]. This catalytic study provides a straightforward synthetic route of the highly functionalized α,β

• -diamino-3,3’-disubstituted-oxindoles 42. These are key intermediates for the preparation of biologically and pharmacologically attractive compounds, such as (+)-alantrypinone [45], (−)-serantrypinone [46] and (−)-lapatin [47]. In the presence of the catalyst 41 (10 mol %), a broad scope of the oxindoles

• the proposed transition state TS12. Addition of 3-oxindoles 39 to 2-amino-1-nitroethenes 40, catalyzed by 41. Michael addition of 1,3-dicarbonyl compounds 36 to the nitroalkenes 3 catalyzed by the squaramide 43. Asymmetric aza-Henry reaction catalyzed by the aminoindanol-derived sulfinyl urea 50

(Thio)urea-mediated synthesis of functionalized six-membered rings with multiple chiral centers

• Giorgos Koutoulogenis,
• Nikolaos Kaplaneris and
• Christoforos G. Kokotos

Beilstein J. Org. Chem. 2016, 12, 462–495, doi:10.3762/bjoc.12.48

• product (Scheme 68). Among the same lines, Zhou, Li and co-workers reported a cascade process affording six-membered spiro-cyclic oxindoles with five adjacent stereocenters. The authors proposed that the reaction proceeds via an asymmetric Michael–Michael aldol sequence (Scheme 69) [88]. In this protocol

• -tert-butylsilyl ether 219 were used, the substituted N-Boc-substituted spiro-oxindoles 220 were obtained. This domino Michael–Michael aldol reaction provides the product in an excellent 94% yield, excellent enantiomeric excess (>99%) and good diastereoselectivity (7:2:1). Utilizing organocatalyst 57

Cupreines and cupreidines: an established class of bifunctional cinchona organocatalysts

• Laura A. Bryant,
• Rossana Fanelli and
• Alexander J. A. Cobb

Beilstein J. Org. Chem. 2016, 12, 429–443, doi:10.3762/bjoc.12.46

• nitro functionality (Scheme 5). Similarly, Kesavan and co-workers reacted 3-O-Boc-oxindoles 23 with MBH carbonates 22 to generate a range of spirocyclic scaffolds containing α-exo-methylene-γ-butyrolactone 24 – again using β-ICPD (Scheme 6) [30]. Nazarov cyclization An asymmetric Nazarov cyclization has

Application of 7-azaisatins in enantioselective Morita–Baylis–Hillman reaction

• Qing He,
• Gu Zhan,
• Wei Du and
• Ying-Chun Chen

Beilstein J. Org. Chem. 2016, 12, 309–313, doi:10.3762/bjoc.12.33

• allows a convenient approach to access multifunctional 3-hydroxy-7-aza-2-oxindoles with high enantiopurity (up to 94% ee). Other types of activated alkenes, such as acrylates and acrolein, could also be efficiently utilized. Keywords: 7-azaisatins; β-isocupreidine; bifunctional catalysis; maleimide; MBH

• addition, 7-azaisatins were also applied in asymmetric synthesis [18][19]. Therefore, with our continuing interest in the catalytic application of bifunctional β-ICD [20][21][22][23], herein we report the enantioselective MBH reaction of 7-azaisatins with maleimides. A series of 3-hydroxy-7-aza-2-oxindoles

• -ICD (Table 2). At first, a variety of N-substituted maleimides 2 were explored in the reaction with 7-azaisatin 1a in toluene. Maleimides bearing an electron-rich N-aryl ring generally afforded the corresponding 3-hydroxy-7-aza-2-oxindoles in high yields and with excellent enantioselectivity (Table 2

Cascade alkylarylation of substituted N-allylbenzamides for the construction of dihydroisoquinolin-1(2H)-ones and isoquinoline-1,3(2H,4H)-diones

• Ping Qian,
• Bingnan Du,
• Wei Jiao,
• Haibo Mei,
• Jianlin Han and
• Yi Pan

Beilstein J. Org. Chem. 2016, 12, 301–308, doi:10.3762/bjoc.12.32

• alkanes resulting in alkyl-substituted oxindoles (Scheme 1a) [43]. However, cyclization of N-allylbenzamides initiated by the functionalization of sp3 C–H bonds of simple alkanes remains unexplored. Very recently, our group developed a metal-free hydroxyalkylation-initiated radical six-membered

Fates of imine intermediates in radical cyclizations of N-sulfonylindoles and ene-sulfonamides

• Hanmo Zhang,
• E. Ben Hay,
• Stephen J. Geib and
• Dennis P. Curran

Beilstein J. Org. Chem. 2015, 11, 1649–1655, doi:10.3762/bjoc.11.181

• -dihydropyrroles also presumably form spiro-imines as primary products. However, the lactam carbonyl group facilitates the ring-opening of these cyclic imines by a new pathway of hydration and retro-Claisen-type reaction, providing rearranged 2-(2'-formamidoethyl)oxindoles. Keywords: ene-sulfonamide; imine

• '-formamidoethyl)-2-oxindoles. These transformations add new dimensions to the growing radical chemistry of ene-sulfonamides. (a) Radical reactions of ene-sulfonamides give diverse isolated products; (b) these products are often derived from transient imine intermediates. Isolation of stable imines strengthens the

Recent advances in the electrochemical construction of heterocycles

• Robert Francke

Beilstein J. Org. Chem. 2014, 10, 2858–2873, doi:10.3762/bjoc.10.303

• method for the synthesis of oxindoles and 3-oxotetrahydroisoquinolines 47 via intramolecular cyclization under C–C-bond formation was reported by Atobe, Fuchigami et al. (Scheme 18) [63]. The protocol is based on the anodic oxidation of α-(phenylthio)acetamides 46 in the presence of Et3N∙3HF. The latter

Chiral phosphines in nucleophilic organocatalysis

• Yumei Xiao,
• Zhanhu Sun,
• Hongchao Guo and
• Ohyun Kwon

Beilstein J. Org. Chem. 2014, 10, 2089–2121, doi:10.3762/bjoc.10.218

• activated isatin-based alkenes (Scheme 39) [76]. The reactions, performed in chloroform in the presence of molecular sieves at room temperature, provided biologically important 3-spirocyclopentene-2-oxindoles with two contiguous quaternary centers in very high yields and with good enantioselectivities; they

• ] cycloadducts, 3-spirocyclohexene-2-oxindoles, in high yields with excellent ee and dr. These asymmetric [4 + 2] annulations of allenoates with activated alkenes significantly offset the limitations of Diels–Alder reactions when synthesizing enantioenriched multisubstituted cyclohexenes. At about the same time

• development of chiral phosphine–assisted asymmetric Michael reactions has lagged behind other phosphine-catalyzed reactions. Recently, using bifunctional chiral amino acid–derived phosphines, Lu and co-workers developed asymmetric Michael additions of oxindoles to α,β-unsaturated carbonyl compounds (Scheme 55

Asymmetric Ugi 3CR on isatin-derived ketimine: synthesis of chiral 3,3-disubstituted 3-aminooxindole derivatives

• Giordano Lesma,
• Fiorella Meneghetti,
• Alessandro Sacchetti,
• Mattia Stucchi and
• Alessandra Silvani

Beilstein J. Org. Chem. 2014, 10, 1383–1389, doi:10.3762/bjoc.10.141

• additions or spiroannulation [2][3]. Oxindoles represent a common structural element in various natural products and biologically active compounds. Diverse oxindole derivatives act as non-peptide scaffolds [4] in peptidomimetic chemistry, either as enzyme inhibitors or as ligands of G-protein-coupled

• receptors [5]. In particular, 3,3-disubstituted 3-amino-2-oxindoles are present in several drug candidates. They exhibit various types of bioactivity, such as the potent gastrin/CCK-B receptor antagonist I [6], the vasopressin VIb receptor antagonist II [7][8], the CRTH2 (DP2) receptor antagonist

• spirohydantoin III [9], and the new antimalarial lead IV [10][11] (Figure 1). Giving the importance of this structural motif, the development of rapid synthetic methods for oxindoles bearing a nitrogen atom at the C3-stereogenic center is highly required [12][13][14][15]. In the course of our studies on new

Allenylphosphine oxides as simple scaffolds for phosphinoylindoles and phosphinoylisocoumarins

• G. Gangadhararao,
• Ramesh Kotikalapudi,
• M. Nagarjuna Reddy and
• K. C. Kumara Swamy

Beilstein J. Org. Chem. 2014, 10, 996–1005, doi:10.3762/bjoc.10.99

• series include phosphonobenzofurans/indenones [21][22], -pyrazoles [23], -chromenes/thiochromenes [24][25], -pyrroles [26], multiply substituted furans [27], indolopyran-1-ones [28], N-hydroxyindolinones [29], and oxindoles [30]. In the reaction shown in Scheme 1a, for the formation of the

Primary-tertiary diamine-catalyzed Michael addition of ketones to isatylidenemalononitrile derivatives

• Akshay Kumar and
• Swapandeep Singh Chimni

Beilstein J. Org. Chem. 2014, 10, 929–935, doi:10.3762/bjoc.10.91

• -component version of the reaction by a domino Knoevenagel–Michael sequence. The Michael adduct 4a was transformed into spirooxindole 6 by a reduction with sodium borohydride in a highly enantioselective manner. Keywords: 3,3'-disubstituted oxindoles; Michael reaction; organocatalysis; primary-tertiary

• attention as novel substrates for the enantioselective synthesis of 3,3'-disubstituted oxindoles [18][19][20][21][22]. The organocatalytic Michael addition of ketones to isatylidenemalononitriles via enamine-catalysis has emerged as a useful tool for the synthesis of 3,3'-disubstituted oxindoles, which

• ][45]. We describe herein that a similar catalyst system could also efficiently catalyze the asymmetric Michael addition reaction between ketones 2 and isatylidenemalononitrile derivatives 3 to procure highly functionalized 3,3'-disubstituted oxindoles 4 which could easily be transformed into

Aminofluorination of 2-alkynylanilines: a Au-catalyzed entry to fluorinated indoles

• Antonio Arcadi,
• Emanuela Pietropaolo,
• Antonello Alvino and
• Véronique Michelet

Beilstein J. Org. Chem. 2014, 10, 449–458, doi:10.3762/bjoc.10.42

• of 3,3-difluoro-2-oxindoles to give the corresponding 3,3-difluoroindoines when electron-withdrawing groups were present as substituents in the benzene nucleus. The 3,3-difluoro-2-oxindoles were prepared by the reaction of appropriately substituted isatin derivatives with DAST [18]. Anodic

Additive-assisted regioselective 1,3-dipolar cycloaddition of azomethine ylides with benzylideneacetone

• Chuqin Peng,
• Jiwei Ren,
• Jun-An Xiao,
• Honggang Zhang,
• Hua Yang and
• Yiming Luo

Beilstein J. Org. Chem. 2014, 10, 352–360, doi:10.3762/bjoc.10.33

• prepare a series of novel spiropyrrolidine-oxindoles – 4′-acetyl-3′,5′-diarylspiro[indoline-3,2′-pyrrolidin]-2-ones and 3′-acetyl-4′,5′-diarylspiro[indoline-3,2′-pyrrolidine]-2-ones in good yields of up to 94% and with good regioselectivities. Regioselectivities are reversible by the addition of water or

• addition of 4-nitrobenzoic acid, which led to the formation of spirooxindoles with novel substitution patterns (Scheme 1). Accordingly, a series of novel functionalized 3-spiropyrrolidine-oxindoles bearing an acetyl group were prepared via this 1,3-dipolar cycloaddition with up to 94% yield. To the best of

The regioselective synthesis of spirooxindolo pyrrolidines and pyrrolizidines via three-component reactions of acrylamides and aroylacrylic acids with isatins and α-amino acids

• Tatyana L. Pavlovskaya,
• Fedor G. Yaremenko,
• Victoria V. Lipson,
• Svetlana V. Shishkina,
• Oleg V. Shishkin,
• Vladimir I. Musatov and
• Alexander S. Karpenko

Beilstein J. Org. Chem. 2014, 10, 117–126, doi:10.3762/bjoc.10.8

• spiro cycloadducts can be obtained in methanol dihydropyrrolizinyl oxindoles are formed in aqueous ethanol media at higher temperatures. Therefore, reactions involving aroylacrylic acids as substrates can afford the product in a regiocontrolled manner. Experimental Reagents and analytics: The 1H NMR

A construction of 4,4-spirocyclic γ-lactams by tandem radical cyclization with carbon monoxide

• Mitsuhiro Ueda,
• Yoshitaka Uenoyama,
• Nozomi Terasoma,
• Shoko Doi,
• Shoji Kobayashi,
• Ilhyong Ryu and
• John A. Murphy

Beilstein J. Org. Chem. 2013, 9, 1340–1345, doi:10.3762/bjoc.9.151

• -spirocyclic oxindole γ-lactams by the cycloaddition of imines and succinic anhydrides [5]. Tandem radical cyclization can also provide a powerful tool for the construction of heterocycles [6][7][8][9][10][11][12]. One of us previously reported on the construction of spirocyclic pyrrolidinyl oxindoles by the

Facile synthesis of functionalized spiro[indoline-3,2'-oxiran]-2-ones by Darzens reaction

• Qin Fu and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2013, 9, 918–924, doi:10.3762/bjoc.9.105

• -alkyl groups and without N-substituent in the presence of potassium carbonate as a base catalyst. When two equivalents phenacyl bromides were used in the reaction, the N-substitution reaction of isatin also finished with the formation of spiro-oxirane-oxindoles. Keywords: Darzens reaction; isatin

• ]. The unique structures and the highly pronounced pharmacological activity displayed by the spirooxindoles have made them attractive synthetic targets [6][7][8][9]. In various heterocyclic and carbocyclic spirooxindoles, the spiro-oxirane-oxindoles are a particular class of compounds with both spiro

• and enantioselective synthesis of versatile spiro-oxirane-oxindoles [14][15][16][17][18][19]. With the aim of expanding our previous studies on the synthesis of various spirooxindoles [20][21][22][23][24][25], we decided to systematically investigate the Darzens reactions of a series of isatins with

Direct alkenylation of indolin-2-ones by 6-aryl-4-methylthio-2H-pyran-2-one-3-carbonitriles: a novel approach

• Sandeep Kumar,
• Ramendra Pratap,
• Abhinav Kumar,
• Brijesh Kumar,
• Vishnu K. Tandon and
• Vishnu Ji Ram

Beilstein J. Org. Chem. 2013, 9, 809–817, doi:10.3762/bjoc.9.92

• hydride-AIBN initiated radical cyclization [33][34]. In 2005, Player and co-workers reported a tandem Heck/Suzuki–Miyaura coupling process for the synthesis of (E)-3,3-(diaryl)oxindoles [35][36][37]. Recently, alkenylation of indolin-2-ones has been developed by palladium-catalyzed aromatic C–H activation

• 3-alkenyl-2-oxindoles being based on expensive catalysts, non-commercially available precursors, and multistep time-consuming synthetic protocols, the development of an efficient, economical and short synthesis was inevitable and desirable. In this regard, we have now developed an efficient new

• protocol for the direct alkenylation of 2-oxindole by 6-aryl-4-methylthio-2H-pyran-2-one-3-carbonitriles 3 to deliver 3-alkenyl-2-oxindoles 8 in moderate yield. This procedure is quite efficient, noncatalytic, economical and easy in workup. Moreover, it opens a new avenue for the synthesis of 3-alkenyl-2

Synthesis of spiro[dihydropyridine-oxindoles] via three-component reaction of arylamine, isatin and cyclopentane-1,3-dione

• Yan Sun,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2013, 9, 8–14, doi:10.3762/bjoc.9.2

• [3][4][5][6]. Isatin and its derivatives may be the most useful starting materials or precursors in the synthesis of a wide number of spirocyclic oxindoles [7][8]. Due to its simple process, easy operation, efficiency and high atomic economy, the multicomponent reaction based on isatin and its

• ][13][14]. Considering the above reports, and as part of our program aimed at developing new multicomponent reactions for the construction of complex heterocyclic compounds, we wish in this work to report the efficient synthesis of unprecedented cyclopentyl-fused spiro[dihydropyridine-oxindoles] by the

• condensation of isatins with cyclic 1,3-dicarbonyl compounds [30][31][32][33], the condensation reaction of isatin with cyclopentane-1,3-dione seemed still not to have been investigated and the 3,3-bis(2-hydroxy-5-oxo-cyclopent-1-enyl)oxindoles 3a–3d have not been prepared until now. Thus, the direct