1,3-Dipolar cycloaddition of nitrones to oxa(aza)bicyclic alkenes

2019 ◽  
Vol 6 (19) ◽  
pp. 3360-3364 ◽  
Author(s):  
Yongqi Yao ◽  
Wen Yang ◽  
Qifu Lin ◽  
Weitao Yang ◽  
Huanyong Li ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Reaction Pathways ◽  
Dipolar Cycloaddition ◽  
Concerted Mechanism ◽  
Mild Conditions

A new 1,3-dipolar cycloaddition of oxa(aza)bicyclic alkenes with nitrones has been developed without any catalyst and additive under mild conditions. The proposed concerted mechanism is investigated by DFT calculations of the reaction pathways.

Reactions of an Aluminium(I) Reagent with 1,2-, 1,3- and 1,5-Dienes: Dearomatisation, Reversibility, and a Pericyclic Mechanism

2019 ◽  
Author(s):  
Clare Bakewell ◽  
Martí Garçon ◽  
Richard Y Kong ◽  
Louisa O'Hare ◽  
Andrew J. P. White ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Dft Calculations ◽  
Transition State ◽  
Reaction Pathways ◽  
Aromatic Rings ◽  
Aromatic Character ◽  
Pericyclic Reaction

The reactions of an aluminium(I) reagent with a series of 1,2-, 1,3- and 1,5-dienes are reported. In the case of 1,3-dienes the reaction occurs by a pericyclic reaction mechanism, specifically a cheletropic cycloaddition, to form aluminocyclopentene containing products. This mechanism has been interrogated by stereochemical experiments and DFT calculations. The stereochemical experiments show that the (4+1) cycloaddition follows a suprafacial topology, while calculations support a concerted albeit asynchronous pathway in which the transition state demonstrates aromatic character. Remarkably, the substrate scope of the (4+1) cycloaddition includes dienes that are either in part, or entirely, contained within aromatic rings. In these cases, reactions occur with dearomatisation of the substrate and can be reversible. In the case of 1,2- or 1,5-dienes complementary reactivity is observed; the orthogonal nature of the C=C π-bonds (1,2-diene) and the homoconjugated system (1,5-diene) both disfavour a (4+1) cycloaddition. Rather, reaction pathways are determined by an initial (2+1) cycloaddition to form an aluminocyclopropane intermediate which can in turn undergo insertion of a further C=C π-bond leading to complex organometallic products that incorporate fused hydrocarbon rings.

Pt-Pd Nanoalloy for the Unprecedented Activation of Carbon-Fluorine Bond at Low Temperature

2019 ◽  
Author(s):  
Raghu Nath Dhital ◽  
keigo nomura ◽  
Yoshinori Sato ◽  
Setsiri Haesuwannakij ◽  
Masahiro Ehara ◽  
...  
Keyword(s):  
Activation Energy ◽  
Low Temperature ◽  
Dft Calculations ◽  
Bond Activation ◽  
Mild Conditions ◽  
Selective Transformation ◽  
Rate Determining Step ◽  
Highly Active ◽  
Harsh Conditions ◽  
Reaction Profile

Carbon-Fluorine (C-F) bonds are considered the most inert organic functionality and their selective transformation under mild conditions remains challenging. Herein, we report a highly active Pt-Pd nanoalloy as a robust catalyst for the transformation of C-F bonds into C-H bonds at low temperature, a reaction that often required harsh conditions. The alloying of Pt with Pd is crucial to activate C-F bond. The reaction profile kinetics revealed that the major source of hydrogen in the defluorinated product is the alcoholic proton of 2-propanol, and the rate-determining step is the reduction of the metal upon transfer of the <i>beta</i>-H from 2-propanol. DFT calculations elucidated that the key step is the selective oxidative addition of the O-H bond of 2-propanol to a Pd center prior to C-F bond activation at a Pt site, which crucially reduces the activation energy of the C-F bond. Therefore, both Pt and Pd work independently but synergistically to promote the overall reaction

Design and synthesis of dichromeno[2,3-b;3′,2′-e]pyridine-12,14-dione to evaluate its optical properties

2017 ◽  
Vol 41 (10) ◽  
pp. 3887-3893 ◽  
Author(s):  
Pritam Biswas ◽  
Jaydip Ghosh ◽  
Tapas Sarkar ◽  
Debabrata Jana ◽  
Chandrakanta Bandyopadhyay
Keyword(s):  
Cyclic Voltammetry ◽  
Optical Properties ◽  
Thermogravimetric Analysis ◽  
Dft Calculations ◽  
Design And Synthesis ◽  
Mild Conditions ◽  
Cv Measurements

An unambiguous synthesis of dichromeno[2,3-b;3′,2′-e]pyridine-12,14-diones has been developed under mild conditions and their optical properties have been evaluated by studying UV-vis absorption and photoluminescence (PL) spectroscopy, cyclic voltammetry (CV) measurements, DFT calculations and thermogravimetric analysis.

Nitroacenaphthene as a New Photocatalyst for the Synthesis of Sulfonyl Amidines

Synthesis ◽  
2019 ◽  
Vol 51 (23) ◽  
pp. 4425-4433
Author(s):  
Yong Jian ◽  
Ming Chen ◽  
Chao Yang ◽  
Wujiong Xia
Keyword(s):  
Visible Light ◽  
Small Molecule ◽  
Reaction Pathways ◽  
Visible Light Photocatalyst ◽  
Mild Conditions ◽  
Sulfonyl Azides ◽  
Site Selective ◽  
First Time

A small molecule, namely nitroacenaphthene, is reported for the first time as a recyclable visible-light photocatalyst for the construction of the C=N bond from sulfonyl azides and amines. This scalable, site-selective protocol provides a convenient way to access various sulfonyl amidines under mild conditions. Two reaction pathways are proposed, according to different transformation patterns.

scholarly journals Synthesis of tetrazole fused azepanes and quantum chemical topology study on the mechanism of the intramolecular cycloaddition reaction

RSC Advances ◽  
2017 ◽  
Vol 7 (79) ◽  
pp. 50367-50371 ◽  
Author(s):  
M. S. Pino-Gonzalez ◽  
A. Romero-Carrasco ◽  
S. Calvo-Losada ◽  
N. Oña-Bernal ◽  
J. J. Quirante ◽  
...  
Keyword(s):  
Quantum Chemical ◽  
Cycloaddition Reaction ◽  
Dipolar Cycloaddition ◽  
Concerted Mechanism ◽  
Intramolecular Cycloaddition ◽  
Chemical Topology ◽  
Quantum Chemical Topology

Syntheses of novel tetrazolo azepanes by intramolecular 1,3-dipolar cycloaddition are described. Cyclization mechanistic topology study showed a pseudo concerted mechanism.

Facile Synthesis of 4,5-Dihydro-1,3,4-Thiadiazoles by 1,3-Dipolar Cycloaddition of Thioisomünchnones

2009 ◽  
Vol 62 (4) ◽  
pp. 356 ◽  
Author(s):  
Bárbara Sánchez ◽  
José Luis Bravo ◽  
María Josí Arívalo ◽  
Ignacio López ◽  
Mark E. Light ◽  
...  
Keyword(s):  
Structure Analysis ◽  
Structure Elucidation ◽  
Room Temperature ◽  
Dipolar Cycloaddition ◽  
Two Dimensional ◽  
Facile Synthesis ◽  
X Ray ◽  
Mild Conditions ◽  
Nmr Techniques

The present paper summarizes a straightforward synthesis of 4,5-dihydro-1,3,4-thiadiazoles by the 1,3-dipolar cycloaddition of thioisomünchnones. These reactions have been carried out in dichloromethane and are essentially complete within 60 min at room temperature. Under such mild conditions the asymmetric version has been explored as well. Unequivocal structure elucidation has been accomplished by means of one- and two-dimensional NMR techniques as well as X-ray structure analysis.

Intramolecular Cycloaddition Approach to Fused Pyrazoles: Access to 4,5-Dihydro-2H-pyrazolo[4,3-c]quinolines, 2,8-Dihydroindeno[2,1-c]pyrazoles, and 4,5-Dihydro-2H-benzo[e]indazoles

Synthesis ◽  
2017 ◽  
Vol 50 (07) ◽  
pp. 1511-1520 ◽  
Author(s):  
Chinmay Chowdhury ◽  
Moumita Jash ◽  
Bimolendu Das ◽  
Suparna Sen
Keyword(s):  
Reaction Mechanism ◽  
Dft Calculations ◽  
Functional Groups ◽  
Efficient Method ◽  
Diazo Compound ◽  
Dipolar Cycloaddition ◽  
Reaction Sequence ◽  
Intramolecular Cycloaddition ◽  
Aromatic Substrate ◽  
Fused Pyrazoles

A straightforward and efficient method for the synthesis of pyrazoles fused with 1,2,3,4-tetrahydroquinoline, 2,3-dihydro-1H-indene­, or 1,2,3,4-tetrahydronaphthalene involves the formation of the tosylhydrazone from an aromatic substrate carrying aldehyde and acetylenic functionalities at appropriate positions, followed by base-promoted generation of the diazo compound and subsequent intramolecular 1,3-dipolar cycloaddition. A number of functional groups were found to be compatible for this reaction sequence and yields were moderate to very good (44–95%). A plausible reaction mechanism supported by DFT calculations has been provided to explain the formation of products.

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