59259-01-7Relevant academic research and scientific papers
A Combined Experimental–Theoretical Study on Diels-Alder Reaction with Bio-Based Furfural: Towards Renewable Aromatics
van Scodeller,De Oliveira Vigier, Karine,Muller, Eric,Ma, Changru,Guégan, Frédéric,Wischert, Raphael,Jér?me, Fran?ois
, p. 313 - 323 (2020/10/19)
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.
Cobalt-Catalyzed Chemoselective Transfer Hydrogenative Cyclization Cascade of Enone-Tethered Aldehydes
Ma, Shuang-Shuang,Jiang, Biao-Ling,Yu, Zheng-Kun,Zhang, Suo-Jiang,Xu, Bao-Hua
, p. 3873 - 3878 (2021/05/26)
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
Catalytic Enantioselective Synthesis of Axially Chiral Diarylmethylidene Indanones
Kumar, Prashant,Shirke, Rajendra P.,Yadav, Sonu,Ramasastry
supporting information, p. 4909 - 4914 (2021/06/30)
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.
Catalytic Synthesis of 8-Membered Ring Compounds via Cobalt(III)-Carbene Radicals
Lankelma, Marianne,Zhou, Minghui,de Bruin, Bas,van der Vlugt, Jarl Ivar
, p. 11073 - 11079 (2020/04/29)
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.
Ring-Opening/Recyclization Cascades of Monoactivated Cyclopropanes
Mishra, Uttam K.,Patel, Kaushalendra,Ramasastry, S. S. V.
supporting information, (2020/05/25)
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
Synthesis of Cyclopropanoids via Substrate-Based Cyclization Pathways
Mishra, Uttam K.,Patel, Kaushalendra,Ramasastry
, p. 175 - 179 (2019/01/04)
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.
Catalytic Dibenzocyclooctene Synthesis via Cobalt(III)–Carbene Radical and ortho-Quinodimethane Intermediates
te Grotenhuis, Colet,van den Heuvel, Naudin,van der Vlugt, Jarl Ivar,de Bruin, Bas
, p. 140 - 145 (2017/12/13)
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.
Nonenzymatic Dynamic Kinetic Resolution of in situ Generated Hemithioacetals: Access to 1,3-Disubstituted Phthalans
Nath, Utpal,Chowdhury, Deepan,Pan, Subhas Chandra
, p. 1628 - 1633 (2018/03/21)
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.).
Enantioselective N-Heterocyclic Carbene Catalysis by the Umpolung of α,β-Unsaturated Ketones
Nakano, Yuji,Lupton, David W.
, p. 3135 - 3139 (2016/03/12)
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
Asymmetric Allylation/RCM-Mediated Synthesis of Fluorinated Benzo-Fused Bicyclic Homoallylic Amines As Dihydronaphthalene Derivatives
Sedgwick, Daniel M.,Barrio, Pablo,Simón, Antonio,Román, Raquel,Fustero, Santos
, p. 8876 - 8887 (2016/10/14)
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.
