34944-05-3Relevant articles and documents
The Importance of 1,5-Oxygen???Chalcogen Interactions in Enantioselective Isochalcogenourea Catalysis
Cockroft, Scott L.,Elmi, Alex,Frost, Aileen B.,Ling, Kenneth B.,McLaughlin, Calum,Morris, Rylie K.,Pascoe, Dominic J.,Slawin, Alexandra M. Z.,Smith, Andrew D.,Smith, Terry K.,Willoughby, Patrick H.,Woods, Andrew M.,Young, Claire M.,de la Houpliere, Alix
supporting information, p. 3705 - 3710 (2020/02/11)
The importance of 1,5-O???chalcogen (Ch) interactions in isochalcogenourea catalysis (Ch=O, S, Se) is investigated. Conformational analyses of N-acyl isochalcogenouronium species and comparison with kinetic data demonstrate the significance of 1,5-O???Ch interactions in enantioselective catalysis. Importantly, the selenium analogue demonstrates enhanced rate and selectivity profiles across a range of reaction processes including nitronate conjugate addition and formal [4+2] cycloadditions. A gram-scale synthesis of the most active selenium analogue was developed using a previously unreported seleno-Hugerschoff reaction, allowing the challenging kinetic resolutions of tertiary alcohols to be performed at 500 ppm catalyst loading. Density functional theory (DFT) and natural bond orbital (NBO) calculations support the role of orbital delocalization (occurring by intramolecular chalcogen bonding) in determining the conformation, equilibrium population, and reactivity of N-acylated intermediates.
Reductive aromatization of oxindoles to 3-substituted indoles
Mandal, Tirtha,Chakraborti, Gargi,Dash, Jyotirmayee
supporting information, (2020/06/21)
A practical and scalable approach for the synthesis of 3-substituted indoles is delineated via hydride nucleophilic addition to 3-substituted-2-oxindoles. The reaction proceeds through reductive aromatization involving indolinium ion intermediate. A wide range of 3-functionalized indoles have been synthesized. The method is employed for the synthesis of 3,3?-bis-indoles and a dimeric 3-indole derivative. Moreover, this protocol is used to obtain naturally occuring amino acid tryptamine.
A C=O???Isothiouronium Interaction Dictates Enantiodiscrimination in Acylative Kinetic Resolutions of Tertiary Heterocyclic Alcohols
Greenhalgh, Mark D.,Smith, Samuel M.,Walden, Daniel M.,Taylor, James E.,Brice, Zamira,Robinson, Emily R. T.,Fallan, Charlene,Cordes, David B.,Slawin, Alexandra M. Z.,Richardson, H. Camille,Grove, Markas A.,Cheong, Paul Ha-Yeon,Smith, Andrew D.
supporting information, p. 3200 - 3206 (2018/02/22)
A combination of experimental and computational studies have identified a C=O???isothiouronium interaction as key to efficient enantiodiscrimination in the kinetic resolution of tertiary heterocyclic alcohols bearing up to three potential recognition motifs at the stereogenic tertiary carbinol center. This discrimination was exploited in the isothiourea-catalyzed acylative kinetic resolution of tertiary heterocyclic alcohols (38 examples, s factors up to >200). The reaction proceeds at low catalyst loadings (generally 1 mol %) with either isobutyric or acetic anhydride as the acylating agent under mild conditions.
Divergent and Orthogonal Approach to Carbazoles and Pyridoindoles from Oxindoles via Indole Intermediates
Mandal, Tirtha,Chakraborti, Gargi,Karmakar, Shilpi,Dash, Jyotirmayee
supporting information, p. 4759 - 4763 (2018/08/24)
The previously unexplored Grignard addition to oxindoles provides a regiospecific approach to 2- and 2,3-disubstituted indole derivatives in high yields via a one-pot aromatization driven dehydration pathway. This method allows a convenient preparation of diallyl indoles that are used as ring-closing metathesis (RCM) precursors for the orthogonal synthesis of pyrido[1,2-a]indoles and carbazoles. The synthetic utility of this method is illustrated by the synthesis of a microtubulin inhibitor and naturally occurring carbazole alkaloids.
FeCl3-Catalyzed Allylation Reactions onto 3-Hydroxy-2-oxindoles: Formal Total Syntheses of Bis-cyclotryptamine Alkaloids, (±)-Chimonanthine, and (±)-Folicanthine
Kinthada, Lakshmana K.,Medisetty, Sai Raghavendra,Parida, Amarchand,Babu, K. Naresh,Bisai, Alakesh
, p. 8548 - 8567 (2017/08/23)
An FeCl3-catalyzed efficient strategy for the allylation reactions of 3-hydroxy-2-oxindoles with allyltrimethylsilane has been developed. The reaction affords a variety of 2-oxindoles having quaternary center at the pseudobenzylic position in an operationally simple and inexpensive procedure. Control experiments using enantioenriched 3-hydroxy-2-oxindole show that the reaction proceeds through in situ generated 2H-indol-2-one (8). The methodology presents an efficient and concise access to the pyrroloindoline alkaloids (±)-deoxyeseroline (1a), (±)-esermethole (1b), (±)-physostigmine (1c), (±)-phenserine (1d), and (±)-physovenine (1e). Eventually, we extrapolated the scope of this methodology to the formal total syntheses of dimeric cyclotyrptamine alkaloids (±)-chimonanthine (3a), (±)-folicanthine (3c), and (±)-calycanthine (4).
Metal-free base-mediated oxidative annulation cascades to 3-substituted-3-hydroxyoxindole and its 3-spirocyclic derivative
Liu, Min,Zhang, Chunxia,Ding, Mingruo,Tang, Bencan,Zhang, Fengzhi
supporting information, p. 4509 - 4514 (2017/10/13)
A simple and efficient method was developed for the construction of the medicinally important 3-substituted-3-hydroxyoxindole and its 3-spirocyclic derivatives with readily available aniline derivatives as starting materials. This highly atom- and step-economical one-pot protocol was carried out under metal-free base-mediated conditions through a novel oxidative annulation strategy with oxygen as the oxidant. The key intermediates were isolated and confirmed. A reasonable reaction pathway was proposed and supported by the preliminary experiments, and the computational studies were carried out to understand the energetics of the key rearrangement reaction.
Schwartz's Reagent-Mediated Regiospecific Synthesis of 2,3-Disubstituted Indoles from Isatins
Ulikowski,Furman
supporting information, p. 149 - 151 (2016/02/03)
An expeditious, functional group-tolerant synthesis of indoles from isatins is described. Isatins are treated with Grignard reagents to yield oxindoles. These, in turn, are reduced with Schwartz's reagent and subjected to nucleophile addition and dehydrat
Homocoupling of 3-Halooxindole via Visible-Light Photocatalysis: A Mild Access to 3,3′-Bioxindoles
Jia, Wen-Liang,He, Jian,Yang, Jia-Jing,Gao, Xue-Wang,Liu, Qiang,Wu, Li-Zhu
, p. 7172 - 7181 (2016/08/30)
This paper introduces a simple way to the homocoupling of tertiary halides induced by photocatalysis. This method features mild reaction conditions, excellent functional group tolerance, high yields, low photocatalyst loading and successful application to the highly sterically hindered systems. On the basis of the reaction results, a novel stable-radical-induced homocoupling reaction mechanism has been proposed.
Synthesis of 3,3-disubstituted oxindoles by one-pot integrated Br?nsted base-catalyzed trichloroacetimidation of 3-hydroxyoxindoles and Br?nsted acid-catalyzed nucleophilic substitution reaction
Piemontesi, Cyril,Wang, Qian,Zhu, Jieping
supporting information, p. 1533 - 1536 (2013/05/08)
Treatment of 3-hydroxyoxindoles with trichloroacetonitrile (1.3 equiv.) and a catalytic amount of DBU (0.1 equiv.) followed by addition of nucleophiles (1.5 equiv.) and diphenylphosphoric acid (0.2 equiv.) afforded the 3,3-disubstituted oxindoles in good to excellent yields. DFT computations supported the notion that the reaction went through the 1-alkyl-2-oxo-2H-indol- 1-ium intermediate.
Kinetic resolution of tertiary alcohols: Highly enantioselective access to 3-hydroxy-3-substituted oxindoles
Lu, Shenci,Poh, Si Bei,Siau, Woon-Yew,Zhao, Yu
supporting information, p. 1731 - 1734 (2013/04/10)
Enantioselective: The first highly enantioselective kinetic resolution of 3-hydroxy-3-substituted oxindoles has been developed through oxidative esterification catalyzed by a N-heterocyclic carbene (see picture). This method uses a simple procedure and provides 3-hydroxy-oxindoles with various substituents at the 3-position in excellent enantiopurity. S=selectivity. Copyright