scholarly journals Mechanistic studies on the CAN-mediated intramolecular cyclization of δ-aryl-β-dicarbonyl compounds

2013 ◽  
Vol 9 ◽  
pp. 1472-1479 ◽  
Author(s):  
Brian M Casey ◽  
Dhandapani V Sadasivam ◽  
Robert A Flowers II
Keyword(s):  
Intramolecular Cyclization ◽  
Computational Studies ◽  
Mechanistic Studies ◽  
Dicarbonyl Compounds ◽  
Radical Intermediates ◽  
Aromatic Substrates ◽  
Site Selectivity ◽  
Intramolecular Cyclizations ◽  
Cyclohexadienyl Radical ◽  
The Stability

The synthesis of 2-tetralones through the cyclization of δ-aryl-β-dicarbonyl substrates by using CAN is described. Appropriately functionalized aromatic substrates undergo intramolecular cyclizations generating 2-tetralone derivatives in moderate to good yields. DFT computational studies indicate that successful formation of 2-tetralones from δ-aryl-β-dicarbonyl radicals is dependent on the stability of the subsequent cyclohexadienyl radical intermediates. Furthermore, DFT computational studies were used to rationalize the observed site selectivity in the 2-tetralone products.

Catalytic Enantioselective Benzylation Directly from Aryl Acetic Acids

2018 ◽  
Author(s):  
Patrick Moon ◽  
Zhongyu Wie ◽  
Rylan Lundgren
Keyword(s):  
Functional Group ◽  
Terminal Event ◽  
Radical Intermediates ◽  
Carbon Carbon Bond ◽  
Or Groups ◽  
Reaction Proceeds ◽  
Wide Availability ◽  
Metal Catalyzed ◽  
The Stability ◽  
Acetic Acids

The stability and wide availability of carboxylic acids make them valuable reagents in chemical synthesis. Most transition metal catalyzed processes using carboxylic acid substrates are initiated by a decarboxylation event that generates reactive carbanion or radical intermediates. Developing enantioselective methodologies relying on these principles can be challenging, as highly reactive species tend to react indiscriminately without selectivity. Furthermore, anionic or radical intermediates generated from decarboxylation can be incompatible with protic and electrophilic functionality, or groups that undergo trapping with radicals. We demonstrate that metal-catalyzed enantioselective benzylation reactions of allylic electrophiles can occur directly from aryl acetic acids. The reaction proceeds via a pathway in which decarboxylation is the terminal event, occurring after stereoselective carbon–carbon bond formation. The mechanistic features of the process enable enantioselective benzylation without the generation of a highly basic nucleophile. Thus, the process has broad functional group compatibility that would not be possible employing established protocols.<br>

Design and Development of Fe-Catalyzed Intra- and Intermolecular Carbofunctionalization of Vinyl Cyclopropanes

2019 ◽  
Author(s):  
Lei Liu ◽  
Wes Lee ◽  
Mingbin Yuan ◽  
Chris Acha ◽  
Michael B. Geherty ◽  
...  
Keyword(s):  
Bond Formation ◽  
Cross Coupling ◽  
Alkyl Halides ◽  
Grignard Reagents ◽  
Mechanistic Studies ◽  
Radical Intermediates ◽  
Design And Implementation ◽  
Solvent Cage ◽  
Radical Cascade ◽  
Radical Processes

Design and implementation of the first (asymmetric) Fe-catalyzed intra- and intermolecular difunctionalization of vinyl cyclopropanes (VCPs) with alkyl halides and aryl Grignard reagents has been realized via a mechanistically driven approach. Mechanistic studies support the diffusion of the alkyl radical intermediates out of the solvent cage to participate in an intra- or -intermolecular radical cascade with the VCP followed by re-entering the Fe radical cross-coupling cycle to undergo selective C(sp2)-C(sp3) bond formation. Overall, we provide new design principles for Fe-mediated radical processes and underscore the potential of using combined computations and experiments to accelerate the development of challenging transformations.

Recent Computational Studies on Mechanisms of Hypervalent Iodine(III)-Promoted Dearomatization of Phenols

2020 ◽  
Vol 24 (18) ◽  
pp. 2106-2117
Author(s):  
Hanliang Zheng ◽  
Xiao-Song Xue
Keyword(s):  
Hypervalent Iodine ◽  
Computational Studies ◽  
Mechanistic Studies

Hypervalent iodine-promoted dearomatization of phenols has received intense attention. This mini-review summarizes recent computational mechanistic studies of phenolic dearomatizations promoted by hypervalent iodine(III) reagents or catalysts. The first part of this review describes mechanisms of racemic dearomatization of phenols, paying special attention to the associative and dissociative pathways. The second part focuses on mechanisms and selectivities of diastereo- or enantio-selective dearomatization of phenols.

scholarly journals Computational Studies of 4-Formylpyridinethiosemicarbazone and Structural and Biological Studies of Its Ni(II) and Cu(II) Complexes

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Mydhili P. Sripathi ◽  
Sireesha Berely ◽  
Chittireddy Venkata Ramana Reddy
Keyword(s):  
Elemental Analysis ◽  
Radical Scavenging ◽  
Molar Conductance ◽  
Computational Studies ◽  
Hydrolytic Cleavage ◽  
Bacterial Strains ◽  
Intercalative Mode ◽  
Biological Studies ◽  
Calf Thymus ◽  
The Stability

To understand the stability, chelation behaviour, and biological activity of 4-Formylpyridinethiosemicarbazone (H4FPT), it is important to recognize its interactive geometry. Hence, computational studies on geometrically optimized structures of thione and thiol forms of H4FPT were performed. Binary metal complexes of the ligand, H4FPT (L) with the Ni(II) and Cu(II) metal ions (M), were synthesized and characterized by various spectroanalytical techniques as elemental analysis, molar conductance, magnetic susceptibility measurements, LC-MS, TGA, IR, UV-Visible, ESR, and powder XRD. Elemental analysis, LC-MS, and TGA studies indicate 1:2 (ML2) composition for mononuclear Ni(II) complex and 1:1 (ML) composition for dinuclear Cu(II) complex. Electronic absorption titrations, fluorescence quenching studies, and viscosity measurements suggest intercalative mode of binding of the complexes with calf thymus DNA (CT-DNA). These complexes also promote hydrolytic cleavage of plasmid pBR322. The ligand (H4FPT) and its complexes showed moderate-to-good activity against Gram-positive and Gram-negative bacterial strains. The DPPH radical scavenging studies showed antioxidant nature of both complexes.

[3,3] Sigmatropic Rearrangement of Some Fluorinated 1,5-Hexadienes

2002 ◽  
Vol 67 (10) ◽  
pp. 1517-1532 ◽  
Author(s):  
William R. Dolbier ◽  
Keith W. Palmer ◽  
Feng Tian ◽  
Piotr Fiedorow ◽  
Andrzej Zaganiaczyk ◽  
...  
Keyword(s):  
Experimental Data ◽  
Ab Initio ◽  
Transition States ◽  
Activation Parameters ◽  
Sigmatropic Rearrangement ◽  
Semiempirical Methods ◽  
Cope Rearrangement ◽  
Computational Studies ◽  
Stepwise Mechanism ◽  
Radical Intermediates

Fluorine atoms incorporated into 1,5-hexadiene molecule should influence the kinetic as well as the thermodynamic parameters of [3,3] sigmatropic rearrangement (Cope rearrangement). Within few decades is has been documented that this transformation proceeds in a concerted manner, rather than stepwise with some radical intermediates involved. Few new terminally fluorinated 1,5-hexadienes (compounds 3, 5A, 7, 9 and 5B) have been synthesized. The activation parameters of rearrangement have been determined and compared with those known for hydrocarbon analogues. While systems developing chair-like transition states (compounds 3 and 5) showed close similarity with hydrocarbon analogues (compound 1), those developing boat-like transition states (compounds 7, 9 and 5B) may proceed through radical stepwise mechanism. Computational studies of the transition states were carried out, showing that only ab initio methods (MP2 and especially DFT) can give approximate correlation with experimental data, whereas in the case of hydrocarbon analogues even simple semiempirical methods (AM1) were reliable enough to reproduce experimental results.

A Formal Metal-Free γ-Arylation of 1,3-Dicarbonyl Compounds via a Sequence of Isomerization/1,4-Addition/[3,3]-Sigmatropic Rearrangement

2021 ◽  
Author(s):  
Shi-Chao Lu ◽  
Fuqiang Wen ◽  
Xidong Guan
Keyword(s):  
Sigmatropic Rearrangement ◽  
Mechanistic Studies ◽  
Dicarbonyl Compounds ◽  
Metal Free

A metal-free redox arylation of alkynes with sulfoxides has been developed to provide an unconventional access to diverse γ-arylated 1,3-dicarbonyl compounds in an atom-economical manner. Mechanistic studies suggest that a...

Intermolecular coupling and intramolecular cyclization of aryl nitriles on Au(111)

2019 ◽  
Vol 55 (77) ◽  
pp. 11611-11614 ◽  
Author(s):  
Henning Klaasen ◽  
Lacheng Liu ◽  
Hong-Ying Gao ◽  
Lena Viergutz ◽  
Philipp A. Held ◽  
...  
Keyword(s):  
Scanning Tunneling Microscopy ◽  
Intramolecular Cyclization ◽  
Scanning Tunneling ◽  
Computational Studies ◽  
Tunneling Microscopy ◽  
Aryl Nitriles ◽  
Dimerization Reaction ◽  
Intermolecular Coupling

The on-surface dimerization reaction of an organic nitrile on Au(111) is reported. The reaction cascade yielding a diazapyrene core was investigated by scanning tunneling microscopy, computational studies and reference compounds.

Metal halide perovskites: stability and sensing-ability

2018 ◽  
Vol 6 (38) ◽  
pp. 10121-10137 ◽  
Author(s):  
Zhaohua Zhu ◽  
Qian Sun ◽  
Zhipeng Zhang ◽  
Jie Dai ◽  
Guichuan Xing ◽  
...  
Keyword(s):  
Metal Halide ◽  
Mechanistic Studies ◽  
External Perturbations ◽  
Halide Perovskites ◽  
The Stability

We review the investigations and mechanistic studies on the stability of metal-halide perovskites under external perturbations, and highlight recent attempts to apply them as sensors.

Computational Studies on the Stability of [Amide]Br-Complexes†

1999 ◽  
Vol 103 (19) ◽  
pp. 3778-3782 ◽  
Author(s):  
Michal Čajan ◽  
Ivan Stibor ◽  
Jaroslav Koča
Keyword(s):  
Computational Studies ◽  
The Stability

TEMPO-mediated homocoupling of aryl Grignard reagents: mechanistic studies

2015 ◽  
Vol 13 (9) ◽  
pp. 2762-2767 ◽  
Author(s):  
Sandip Murarka ◽  
Juri Möbus ◽  
Gerhard Erker ◽  
Christian Mück-Lichtenfeld ◽  
Armido Studer
Keyword(s):  
Grignard Reagents ◽  
Computational Studies ◽  
Mechanistic Studies

The mechanism of TEMPO mediated oxidative homo-coupling of aryl Grignard reagents to biphenyls is investigated in detail by experimental and computational studies.

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