Recent developments in enantioselective photocatalysis

• Callum Prentice,
• James Morrisson,
• Andrew D. Smith and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2020, 16, 2363–2441, doi:10.3762/bjoc.16.197

• examples, up to 99:1 er). This methodology was later expanded to 2-oxindoles 140 [67] and 1,2-diketones 141 [68] to form the corresponding radical coupling products 142 (43 examples, up to 98:2 er) and 143 (30 examples, up to 99:1 er), respectively, in comparable yields and enantioselectivities to those of

Oxime radicals: generation, properties and application in organic synthesis

• Igor B. Krylov,
• Stanislav A. Paveliev,
• Alexander S. Budnikov and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2020, 16, 1234–1276, doi:10.3762/bjoc.16.107

• relatively low yield of product 138f was explained by the steric effect of the ortho-methyl substituent in amide 137. In most cases, N-aryl-N-methylmethacrylamides were used for this cyclization to obtain oxindoles (products 138a–g) except for one example where a homologous amide was used to obtain six

Copper catalysis with redox-active ligands

• Agnideep Das,
• Yufeng Ren,
• Cheriehan Hessin and
• Marine Desage-El Murr

Beilstein J. Org. Chem. 2020, 16, 858–870, doi:10.3762/bjoc.16.77

• metalloenzymatic active site was not characterized in detail, it might bear some resemblance to the original biological active site. Building on their previously discussed phenol oxidation methodology (Scheme 5 and Scheme 6), Lumb and co-workers have targeted subsequent C–N bond formation to access oxindoles [34

Recent advances in Cu-catalyzed C(sp³)–Si and C(sp³)–B bond formation

• Balaram S. Takale,
• Ruchita R. Thakore,
• Elham Etemadi-Davan and
• Bruce H. Lipshutz

Beilstein J. Org. Chem. 2020, 16, 691–737, doi:10.3762/bjoc.16.67

The reaction of arylmethyl isocyanides and arylmethylamines with xanthate esters: a facile and unexpected synthesis of carbamothioates

• Narasimhamurthy Rajeev,
• Toreshettahally R. Swaroop,
• Ahmad I. Alrawashdeh,
• Shofiur Rahman,
• Abdullah Alodhayb,
• Seegehalli M. Anil,
• Kuppalli R. Kiran,
• Chandra,
• Paris E. Georghiou,
• Kanchugarakoppal S. Rangappa and
• Maralinganadoddi P. Sadashiva

Beilstein J. Org. Chem. 2020, 16, 159–167, doi:10.3762/bjoc.16.18

• ], iron nanoparticle-catalyzed reactions of 2-naphthol with benzaldehyde and some of its derivatives with thiourea [22], isothiocyanato oxindoles with ketones [23], ammonium isothiocyanates with chalcones [24], and α-isothiocyanato esters with α-keto amides [25]. Among the synthetic methods available for

Recent advances in transition-metal-catalyzed incorporation of fluorine-containing groups

• Xiaowei Li,
• Xiaolin Shi,
• Xiangqian Li and
• Dayong Shi

Beilstein J. Org. Chem. 2019, 15, 2213–2270, doi:10.3762/bjoc.15.218

• -butyl)borohydride (ʟ-Selectride). The syn-β-fluoro-α-hydroxy esters were obtained finally in good yields with excellent enantioselectivities (83–95% ee). There are two examples of a Pd-catalyzed fluorination of oxindoles. In 2012, Shi and co-workers [41] described the enantioselective asymmetric

• fluorination of oxindoles with an axially chiral C2-symmetric N-heterocyclic carbene (NHC) palladium complex as a catalyst (Scheme 7a). The corresponding products were obtained in excellent yields but low to moderate enantioselectivities. Meanwhile, Wu and co-workers [42] developed a similar system using a

• (Scheme 31a) [74]. Che and co-workers [75] achieved a similar α-fluorination of β-ketoesters and N-Boc-oxindoles (Scheme 31b). Compared with Du’s method, Che employed both AgClO4 and chiral iron(III)-salan complexes as the catalyst. In 2016, the group of Nishikata [76] described a copper-catalyzed site

Synthesis of non-racemic 4-nitro-2-sulfonylbutan-1-ones via Ni(II)-catalyzed asymmetric Michael reaction of β-ketosulfones

• Alexander N. Reznikov,
• Anastasiya E. Sibiryakova,
• Marat R. Baimuratov,
• Eugene V. Golovin,
• Victor B. Rybakov and
• Yuri N. Klimochkin

Beilstein J. Org. Chem. 2019, 15, 1289–1297, doi:10.3762/bjoc.15.127

• acceptors and aldehydes [27][28][29][30][31][32], ketones [33], α-cyano esters [34][35], β-keto esters [35], β-keto acids [36], thiomalonates [37], nitroalkanes [38], oxindoles [39] and thiols [40] as Michael donors. There are only few examples of the use of sulfones as Michael donors in asymmetric addition

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

• Benzo-fused γ-lactam rings such as isoindolin-2-ones and 2-oxindoles are part of the structure of many pharmaceutically active molecules. They can be often synthesized by means of multicomponent approaches and recent contributions in this field are summarized in this review. Clear advantages of these

• -oxindoles; Introduction Pyrrolidin-2-ones (I, Figure 1) are heterocycles that contain a γ-lactam ring that can be found in many biologically active compounds with natural or synthetic origin [1]. When an aryl group is fused to the 3- and 4-positions of the five-membered heterocycle, isoindolinones (II

• , Figure 1) are generated, while if such fusion takes place between the 4- and 5-positions of the γ-lactam ring, 2-oxindoles (also named as indolin-2-ones III, Figure 1) are formed. The isoindolinone structural motif is a part of the core of many natural products [2]. To cite some examples, cichorine [3

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

• developed a novel ring-opening of cyclopropanols 91 with acrylamides 122 for the synthesis of oxindoles 123 (Scheme 30) [110]. A series of desired γ-carbonylalkyl-substituted oxindoles 123 were synthesized between N-phenyl acrylamides 122 and tertiary cyclopropanols 91 through Na2S2O8-promoted radical

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

• Helene Pellissier Aix-Marseille Univ, CNRS, Centrale Marseille, iSm2, Marseille, France 10.3762/bjoc.14.114 Abstract This review collects the recent developments in the synthesis of chiral 3-substituted 3-amino-2-oxindoles based on enantioselective catalytic nucleophilic additions to isatin

• imines published since the beginning of 2015. Keywords: asymmetric synthesis; chiral 3-amino-2-oxindoles; chirality; isatin imines; nucleophilic addition; Introduction Chiral oxindoles represent an important class of products widely present in nature and exhibiting many biological activities. Among

• them, chiral 3-substituted 3-amino-2-oxindoles constitute privileged candidates in medicinal chemistry [1][2][3][4][5][6][7][8]. Consequently, the development of novel catalytic routes to produce these compounds is highly desired [9][10][11][12][13][14][15][16][17][18][19] with a special mention for

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

• carbon centers under basic conditions providing molecular diversity and a small library of spirocyclic oxindoles. Keywords: convertible isocyanides; lactams; molecular diversity; oxindoles; transamidation; Introduction The Ugi-multicomponent coupling reaction [1][2], followed by post-modification

• bonds and functionality towards the construction of synthetic scaffolds. The synthesis of spirocyclic oxindoles has always been of key interest to organic chemists because of significant biological activity [16][17][18][19][20] and their presence in naturally occurring molecules [21][22][23

• 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

Progress in copper-catalyzed trifluoromethylation

• Guan-bao Li,
• Chao Zhang,
• Chun Song and
• Yu-dao Ma

Beilstein J. Org. Chem. 2018, 14, 155–181, doi:10.3762/bjoc.14.11

• -catalyzed trifluoromethylation of N-aryl acrylamides using Langlois’ reagent (CF3SO2Na) as a trifluoromethyl source and water as the reaction medium (Scheme 36). A variety of CF3-containing oxindoles bearing a quaternary carbon center were formed under this conditions. Furthermore, more CF3SO2Na (3.0 equiv

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

• tandem trifluoromethylation/cyclisation processes. Dolbier and co-workers first proposed the use of N-arylacrylamides 3 to access trifluoromethylated 3,3-disubstituted 2-oxindoles 4 under photocatalytic conditions (Scheme 4) [11]. In the presence of Ru(phen)3Cl2 (phen = phenanthroline), a variety of N

• -arylacrylamides para-substituted on their aryl moiety by electron-donating or electron-withdrawing groups were converted into the corresponding oxindoles with similarly good yields. However, the reaction was compatible only with acrylamides bearing methyl or phenyl as R1 and R2 groups; for example, N-acyl and N

• , Shibata, Toru and co-workers used CF3SO2Cl for the enantioselective chlorination of β-ketoesters and oxindoles in the presence of a dbfox-Ph/Ni(II) system (dbfox-Ph = [(R,R)-4,6-dibenzofurandiyl-2,2'-bis(4-phenyloxazoline)]) (Scheme 42) [58]. The reaction proceeded in good to excellent yields and

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

• failed to give the expected product. With a substituent at the meta-position of the aniline ring, a mixture of regioisomers was obtained. Various alkenes with substituents (R3) were investigated and the oxindoles were obtained in moderate to high yields (Scheme 24). Simultaneously, Lei and co-workers

• methacrylamides, so far described, provided oxindoles via a 5-exo trig cyclization. Starting from cinnamamides 53, Mai, Xiao and co-workers reported a 6-endo trig cyclisation leading to 3,4-disubstituted dihydroquinolin-2(1H)-ones 54 (Scheme 30) [52]. Ag(I) was oxidised by the persulfate anion (S2O82–) to

Chiral phase-transfer catalysis in the asymmetric α-heterofunctionalization of prochiral nucleophiles

• Johannes Schörgenhumer,
• Maximilian Tiffner and
• Mario Waser

Beilstein J. Org. Chem. 2017, 13, 1753–1769, doi:10.3762/bjoc.13.170

• investigated. In 2008, Itoh’s group described the α-hydroxylation of oxindoles 17 under phase-transfer conditions by using air in combination with (EtO)3P as the oxygenation system (Scheme 8, upper reaction) [111]. Very recently, Zhao et al. then developed this elegant methodology further by identifying the

• trichloroacetonitrile (Cl3CCN) [118]. This combination leads to the in situ formation of peroxy imidic acid 24, which then serves as the O-transfer reagent for the asymmetric α-hydroxylation of oxindoles 17 in the presence of the chiral triazolium-based ion pairing catalyst L1 (Scheme 11). Very recently, Toullec and co

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

• simple 3-substituted oxindoles and nitrovinylacetamide as starting materials was achieved successfully. This protocol features operational simplicity, high atom economy, and high catalytic asymmetry, thus representing a versatile approach to the synthesis of highly enantioenriched

• [35] (Scheme 1, reaction 1A) and Michael–Henry cascade reactions [25] (Scheme 1, reaction 1B) reported by Barbas III's group involve the cyclization between α,β-unsaturated aldehydes and nitrostyrenes with 3-substituted oxindoles to generate the corresponding CHO- or NO2-substituted spirooxindole

• -catalyzed Michael addition/intramolecular silyl nitronate-olefin cycloaddition (ISOC)/fragmentation sequence to produce highly enantioenriched spirocyclopentaneoxindoles containing an oxime functional group from easily accessible 3-allyl-substituted oxindoles and nitroolefins, which has received wide

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