- Cobalt-Catalyzed Chemoselective Transfer Hydrogenative Cyclization Cascade of Enone-Tethered Aldehydes
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The ligand-free Co-catalyzed chemoselective reductive cyclization cascade of enone-tethered aldehydes with i-PrOH as the environmentally benign hydrogen surrogate is developed by this study. Mechanistic studies disclosed that such a protocol is initiated
- Ma, Shuang-Shuang,Jiang, Biao-Ling,Yu, Zheng-Kun,Zhang, Suo-Jiang,Xu, Bao-Hua
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supporting information
p. 3873 - 3878
(2021/05/26)
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- Catalytic Enantioselective Synthesis of Axially Chiral Diarylmethylidene Indanones
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We describe the first atropselective Suzuki-Miyaura cross-coupling of β-keto enol triflates to access axially chiral (Z)-diarylmethylidene indanones (DAIs). The chemical, physical, and biological properties of DAIs are unknown, despite their being structurally similar to arylidene indanones, primarily due to the lack of racemic or chiral methods. Through this work, we demonstrate a general and efficient protocol for the racemic as well as the atropselective synthesis of (Z)-DAIs. An unusual intramolecular Morita-Baylis-Hillman reaction is utilized for the Z-selective synthesis of β-keto enol triflates.
- Kumar, Prashant,Shirke, Rajendra P.,Yadav, Sonu,Ramasastry
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supporting information
p. 4909 - 4914
(2021/06/30)
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- A Combined Experimental–Theoretical Study on Diels-Alder Reaction with Bio-Based Furfural: Towards Renewable Aromatics
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The synthesis of relevant renewable aromatics from bio-based furfural derivatives and cheap alkenes is carried out by using a Diels-Alder/aromatization sequence. The prediction and the control of the ortho/meta selectivity in the Diels-Alder step is an important issue to pave the way to a wide range of renewable aromatics, but it remains a challenging task. A combined experimental-theoretical approach reveals that, as a general trend, ortho and meta cycloadducts are the kinetic and thermodynamic products, respectively. The nature of substituents, both on the dienes and dienophiles, significantly impacts the feasibility of the reaction, through a modulation on the nucleo- and electrophilicity of the reagents, as well as the ortho/meta ratio. We show that the ortho/meta selectivity at the reaction equilibrium stems from a subtle interplay between charge interactions, favoring the ortho products, and steric interactions, favoring the meta isomers. This work also points towards a path to optimize the aromatization step.
- van Scodeller,De Oliveira Vigier, Karine,Muller, Eric,Ma, Changru,Guégan, Frédéric,Wischert, Raphael,Jér?me, Fran?ois
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p. 313 - 323
(2020/10/19)
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- Ring-Opening/Recyclization Cascades of Monoactivated Cyclopropanes
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A variety of cyclopropyl aryl ketones undergo uncatalyzed cascade ring-opening/recyclization reactions to generate indenones and fluorenones. In addition, a new strategy to access 3-hydroxyindanones possessing two contiguous stereogenic centers, one of th
- Mishra, Uttam K.,Patel, Kaushalendra,Ramasastry, S. S. V.
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supporting information
(2020/05/25)
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- Catalytic Synthesis of 8-Membered Ring Compounds via Cobalt(III)-Carbene Radicals
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The metalloradical activation of o-aryl aldehydes with tosylhydrazide and a cobalt(II) porphyrin catalyst produces cobalt(III)-carbene radical intermediates, providing a new and powerful strategy for the synthesis of medium-sized ring structures. Herein we make use of the intrinsic radical-type reactivity of cobalt(III)-carbene radical intermediates in the [CoII(TPP)]-catalyzed (TPP=tetraphenylporphyrin) synthesis of two types of 8-membered ring compounds; novel dibenzocyclooctenes and unprecedented monobenzocyclooctadienes. The method was successfully applied to afford a variety of 8-membered ring compounds in good yields and with excellent substituent tolerance. Density functional theory (DFT) calculations and experimental results suggest that the reactions proceed via hydrogen atom transfer from the bis-allylic/benzallylic C?H bond to the carbene radical, followed by two divergent processes for ring-closure to the two different types of 8-membered ring products. While the dibenzocyclooctenes are most likely formed by dissociation of o-quinodimethanes (o-QDMs) which undergo a non-catalyzed 8π-cyclization, DFT calculations suggest that ring-closure to the monobenzocyclooctadienes involves a radical-rebound step in the coordination sphere of cobalt. The latter mechanism implies that unprecedented enantioselective ring-closure reactions to chiral monobenzocyclooctadienes should be possible, as was confirmed for reactions mediated by a chiral cobalt-porphyrin catalyst.
- Lankelma, Marianne,Zhou, Minghui,de Bruin, Bas,van der Vlugt, Jarl Ivar
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supporting information
p. 11073 - 11079
(2020/04/29)
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- Synthesis of Cyclopropanoids via Substrate-Based Cyclization Pathways
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A series of unexpected reactions triggered by the dimethyloxosulfonium methylide led to the discovery of unconventional approaches for the synthesis of cyclopropa-fused tetralones and indeno-spirocyclopropanes. These highly functionalized structures were further elaborated in one step to privileged scaffolds such as tetralones, indenones, and fluorenones. As a whole, the results presented herein establish new diversity-oriented folding pathways.
- Mishra, Uttam K.,Patel, Kaushalendra,Ramasastry
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supporting information
p. 175 - 179
(2019/01/04)
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- Catalytic Dibenzocyclooctene Synthesis via Cobalt(III)–Carbene Radical and ortho-Quinodimethane Intermediates
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The metalloradical activation of ortho-benzallylaryl N-tosyl hydrazones with [Co(TPP)] (TPP=tetraphenylporphyrin) as the catalyst enabled the controlled exploitation of the single-electron reactivity of the redox non-innocent carbene intermediate. This method offers a novel route to prepare eight-membered rings, using base metal catalysis to construct a series of unique dibenzocyclooctenes through selective Ccarbene?Caryl cyclization. The desired eight-membered-ring products were obtained in good to excellent yields. A large variety of aromatic substituents are tolerated. The proposed reaction mechanism involves intramolecular hydrogen atom transfer (HAT) to CoIII–carbene radical intermediates followed by dissociation of an ortho-quinodimethane that undergoes 8π cyclization. The mechanism is supported by DFT calculations, and the presence of radical-type intermediates was confirmed by trapping experiments.
- te Grotenhuis, Colet,van den Heuvel, Naudin,van der Vlugt, Jarl Ivar,de Bruin, Bas
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supporting information
p. 140 - 145
(2017/12/13)
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- Nonenzymatic Dynamic Kinetic Resolution of in situ Generated Hemithioacetals: Access to 1,3-Disubstituted Phthalans
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The first nonenzymatic DKR reaction of hemithioacetals is developed. Hemithioacetals were formed in situ via thiol addition and subsequently underwent an intramolecular oxa-Michael reaction. The scope of the reaction was quite broad ranging from aliphatic to aromatic substituents and 1,3-disubstituted-1,3-dihyroisobenzofuran products were obtained in good yields with moderate diastereoselectivities and high enantioselectivities. (Figure presented.).
- Nath, Utpal,Chowdhury, Deepan,Pan, Subhas Chandra
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supporting information
p. 1628 - 1633
(2018/03/21)
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- Enantioselective N-Heterocyclic Carbene Catalysis by the Umpolung of α,β-Unsaturated Ketones
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N-Heterocyclic carbene-catalyzed formation of β-anionic intermediates from enones has been employed in the enantioselective synthesis of 2-aryl propionates. The reaction was achievable using a homochiral 4-MeOC6H4 morpholinone cataly
- Nakano, Yuji,Lupton, David W.
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supporting information
p. 3135 - 3139
(2016/03/12)
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- Asymmetric Allylation/RCM-Mediated Synthesis of Fluorinated Benzo-Fused Bicyclic Homoallylic Amines As Dihydronaphthalene Derivatives
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Enantiomerically enriched fluorinated benzo-fused bicyclic homoallylic amines have been synthesized through an asymmetric allylation/ring closing metathesis (RCM) sequence. This sequence has been carried out using α-trifluoromethylstyrene derivatives as key intermediates, synthesized by microwave radiation. The great deactivating effect exerted by such substituents has been brought to light by a comparative study.
- Sedgwick, Daniel M.,Barrio, Pablo,Simón, Antonio,Román, Raquel,Fustero, Santos
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p. 8876 - 8887
(2016/10/14)
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- PENTAARYLBIIMIDAZOLE COMPOUND AND METHOD FOR PRODUCING THE COMPOUND
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PROBLEM TO BE SOLVED: To provide an industrially usable photochromic compound which solves problems of a conventional photochromic material that the material is insufficient in terms of coloring and decoloring speeds and durability, and that there are man
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Paragraph 0031; 0034
(2018/10/10)
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- Novel ether and thioether macrocycles from phthalaldehyde
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Abstract By reaction of phthalaldehyde (benzene-1,2-dicarbaldehyde) with ethane-1,2-diol or 2-mercaptoethanol, macrocycles containing respectively 14- and 12-membered polyether/thioether rings were obtained in low but reproducible yields, and their struct
- Aitken, R. Alan,Hauduc, Clémence,Mclennan, Ross S.,Slawin, Alexandra M.Z.,Wilson, Heather S.
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supporting information
p. 1937 - 1940
(2015/03/30)
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- Organocatalytic, Enantioselective, intramolecular oxa-michael reaction of alkoxyboronate: A new strategy for enantioenriched 1-substituted 1,3-Dihydroisobenzofurans
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An unprecedented strategy for the synthesis of enantioenriched 1-substituted 1,3-dihydroisobenzofurans via an enantioselective oxa-Michael reaction of o-alkoxyboronate containing chalcone (II) has been accomplished employing cinchona alkaloid based squara
- Ravindra, Barnala,Das, Braja Gopal,Ghorai, Prasanta
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supporting information
p. 5580 - 5583
(2015/02/19)
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- NHC-catalyzed oxidative cyclization reaction for the synthesis of 3-substituted phthalides
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An efficient NHC-catalyzed domino oxidation/oxa-Michael addition reaction of 2-alkenylbenzaldehydes has been developed to afford 3-substituted phthalides bearing a C3-stereogenic center with a broad substrate scope and wide functional group tolerance. The preliminary results of the asymmetric process have been provided as well. the Partner Organisations 2014.
- Youn, So Won,Song, Hyoung Sub,Park, Jong Hyub
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supporting information
p. 2388 - 2393
(2014/04/03)
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- Pentaarylbiimidazole, PABI: An easily synthesized fast photochromic molecule with superior durability
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We report a new type of fast photochromic imidazole dimer, pentaarylbiimidazole (PABI), which shows a few μs fast photochromism with high fatigue resistance against light irradiation. PABI has an unusual spiroconjugated imidazoisoindole skeleton and its d
- Yamashita, Hiroaki,Abe, Jiro
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supporting information
p. 8468 - 8471
(2014/07/22)
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- One-pot syntheses of isoquinolin-3-ones and benzo-1,4-diazepin-2,5-diones utilizing Ugi-4CR post-transformation strategy
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One-pot and efficient syntheses of structurally diverse isoquinolin-3-ones and isoquinolin-3-one-based benzo-1,4-diazepin-2,5-diones have been developed. The notable features of the process include the Ugi condensation of monomasked phthalaldehydes with a
- Che, Chao,Li, Song,Yu, Zhixiong,Li, Fangfang,Xin, Shengchang,Zhou, Liyan,Lin, Shuo,Yang, Zhen
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supporting information
p. 202 - 207
(2013/05/09)
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- Functionalization of acetalic C(sp3)-H bonds by scandium(III) triflate-catalyzed intramolecular redox reactions: Tandem 1,4-hydride transfer/1,5-cyclization processes leading to protected 1-indanones
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A new C-C bond forming reaction leading to adjacent quaternary carbons is reported. It is a one-pot hydride shift/cyclization process facilitated by the hydricity of the acetalic C-H bonds, with benzylidenemalonate fragments as electrophilic hydride accep
- Alajarin, Mateo,Marin-Luna, Marta,Vidala, Angel
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scheme or table
p. 557 - 562
(2011/04/26)
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- Vinyl Azides in Heterocyclic Synthesis. Part 6. Synthesis of Isoquinolines by Intramolecular Aza-Wittig Reaction
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Azidocinnamates containing ortho-carbonyl substituents are versatile intermediates for heterocyclic synthesis.Isoquinolines (8) and (9) are formed under mild neutral conditions by intramolecular aza-Wittig reactions of iminophosphoranes, readily derived f
- Hickey, Deirdre M. B.,MacKenzie, A. Roderick,Moody, Christopher J.,Rees, Charles W.
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p. 921 - 926
(2007/10/02)
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- Iminium Ion Mediated Cyclizations of 4-Aryl-1,4-dihydropyridines. Bridging with Acetals, Carbonyls, and Thiocarbonyls
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The preparation of new aldehyde and acetal derivatives of 4-aryl-1,4-dihydropyridines has been carried out.Treatment of these compounds under acid conditions affords novel caged molecules derived from sequential intramolecular addition reactions.This proc
- Hartman, George D.,Phillips, Brian T.,Halczenko, Wasyl
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p. 2423 - 2427
(2007/10/02)
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- Tricyclic (azeto-isoquinoline) β-lactams
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A new compound with a nucleus containing a benzo-fused carbocyclic β-lactam system is disclosed. The compound has antibacterial activity against B. subtilis.
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