scholarly journals (4+3)-cycloaddition chemists of oxidopyridinium ions and related study

2019 ◽  
Author(s):  
◽  
Chencheng Fu
Keyword(s):  
Uv Radiation ◽  
Photochemical Reaction ◽  
Functional Group ◽  
Cycloaddition Reaction ◽  
Product Yield ◽  
Membered Ring ◽  
Starting Material ◽  
Unsaturated Ester ◽  
Rapid Access ◽  
Cyclobutane Ring

The (4+3)-cycloaddition reaction is a cycloaddition between a 4-atom species and a 3-atom species to form a seven-membered ring. This reaction results in the formation of seven-membered rings. Our research expanded the scope of (4+3)-cycloaddition reaction by using the oxidopyridinium species as the dienophile -- the 3-atom species. By adding an electron-withdrawing functional group to the starting material, we were be able to get good to excellent product yield. The process provides rapid access to bicyclic nitrogenous structures resembling natural alkaloids. [2+2]-Photocycloaddition is a cycloaddition between two olefins to form a cyclobutane ring. The intramolecular [2+2]-cycloaddition of nitrogen-substituted alkenes can be employed to make complicated alkaloids. Our previous work made the 7-azabicyclo[4.3.1]deca-3,8-diene skeleton, which is a nice substrate for the cycloaddition. Under UV radiation, the heteroatom-substituted unsaturated ester undergoes intramolecular [2+2]-cycloaddition with the cyclic alkene to make a cage-like ketone in good to excellent yield, giving rise to a rigid tropane-like alkaloid skeleton. The scope and mechanism of the photochemical reaction will be discussed.

Palladium-catalyzed [4 + 3] dearomatizing cycloaddition reaction of N-iminoquinolinium ylides

2020 ◽  
Vol 7 (18) ◽  
pp. 2612-2617
Author(s):  
Wenhao Dai ◽  
Chunpu Li ◽  
Yichu Liu ◽  
Xu Han ◽  
Xingjun Li ◽  
...  
Keyword(s):  
Functional Group ◽  
Cycloaddition Reaction ◽  
Membered Ring ◽  
Efficient Approach ◽  
Mild Conditions ◽  
Palladium Catalyzed

An efficient approach to obtain saturated seven-membered ring containing three heteroatoms has been developed by using a palladium-catalyzed [4 + 3] dearomatizing cycloaddition. This approach features mild conditions and good functional group tolerance.

Catalytic Synthesis of Cyclic Guanidines via Hydrogen Atom Transfer and Radical-Polar Crossover

2020 ◽  
Author(s):  
Shunya Ohuchi ◽  
Hiroki Koyama ◽  
Hiroki Shigehisa
Keyword(s):  
Hydrogen Atom ◽  
Functional Group ◽  
Hydrogen Atom Transfer ◽  
Catalytic Synthesis ◽  
Membered Ring ◽  
Biologically Active ◽  
Atom Transfer ◽  
Powerful Method ◽  
Protective Groups ◽  
The Common

A catalytic synthesis of cyclic guanidines, which are found in many biologically active compounds and natu-ral products, was developed, wherein transition-metal hydrogen atom transfer and radical-polar crossover were employed. This mild and functional-group tolerant process enabled the cyclization of alkenyl guanidines bearing common protective groups, such as Cbz and Boc. This powerful method not only provided the common 5- and 6-membered rings but also an unusual 7-membered ring. The derivatization of the products afforded various heterocycles. We also investigated the se-lective cyclization of mono-protected or hetero-protected (TFA and Boc) alkenyl guanidines and their further derivatiza-tions.

Tropolone-Based Treatments for Visualising Latent Fingermarks on Porous Surfaces

2019 ◽  
Author(s):  
Clara M. Agapie ◽  
Melissa Sampson ◽  
William Gee
Keyword(s):  
Amino Acids ◽  
Uv Radiation ◽  
Membered Ring ◽  
Diazonium Salts ◽  
Chemical Detection ◽  
Latent Fingerprints ◽  
Porous Surfaces

The work describes a new chemical means of visualising latent fingerprints (fingermarks) using tropolone. Tropolone reacts with amino acids within the fingermark residue to form adducts that absorb UV radiation. These adducts provide useful contrast on highly-fluorescent prous surfaces will illuminated with UV radiation. The conjugated seven-membered ring of the tropolone adduct can be reacted further diazonium salts, which is demonstrated here with formation of two dyes. The methodology is extremely rapid, occurring in minutes with mild heating, and can be applied before ninhydrin in a chemical detection sequence. <br>

Rapid Access to Novel 1,2,3-Triazolo-Heterocyclic Scaffolds via Tandem Knoevenagel Condensation/Azide–Alkyne 1,3-Dipolar Cycloaddition Reaction in One Pot

2014 ◽  
Vol 16 (9) ◽  
pp. 466-477 ◽  
Author(s):  
Ram Awatar Maurya ◽  
Praveen Reddy Adiyala ◽  
D. Chandrasekhar ◽  
Chada Narsimha Reddy ◽  
Jeevak Sopanrao Kapure ◽  
...  
Keyword(s):  
Knoevenagel Condensation ◽  
Cycloaddition Reaction ◽  
Dipolar Cycloaddition ◽  
One Pot ◽  
Rapid Access

ChemInform Abstract: Synthesis of Enantiopure 3-Azabicyclo[3.3.0]octen-7-one Derivatives via Intramolecular Pauson-Khand Cycloaddition Reaction Using Tri-O-acetyl-D-glucal as Starting Material.

ChemInform ◽  
2010 ◽  
Vol 33 (39) ◽  
pp. no-no
Author(s):  
Pilar Areces ◽  
M. Angeles Duran ◽  
Joaquin Plumet ◽  
Michael B. Hursthouse ◽  
Mark E. Light
Keyword(s):  
Cycloaddition Reaction ◽  
Starting Material

Rh(III)-catalyzed annulated coupling of sulfoxonium ylides and iodonium ylides: a rapid access to isocoumarins

2022 ◽  
Author(s):  
Chuanliu Yin ◽  
Lianghao Li ◽  
Chuanming Yu
Keyword(s):  
Functional Group ◽  
Direct Synthesis ◽  
Rapid Access ◽  
Iodonium Ylides

Direct synthesis of isocoumarin skeletons has been realized through Rh(III)-Catalyzed [3 + 3] annulation of sulfoxonium ylides and iodonium carbenes. The synthetic protocol constructed efficiently with the broad functional group...

scholarly journals Addition of lithiated enol ethers to nitrones and subsequent Lewis acid induced cyclizations to enantiopure 3,6-dihydro-2H-pyrans – an approach to carbohydrate mimetics

2010 ◽  
Vol 6 ◽  
Author(s):  
Fabian Pfrengle ◽  
Hans-Ulrich Reissig
Keyword(s):  
Lewis Acid ◽  
Functional Group ◽  
Tricarboxylic Acid ◽  
Membered Ring ◽  
Enol Ether ◽  
Enol Ethers ◽  
Acidic Conditions ◽  
Hydroxylamine Derivatives

A stereodivergent synthesis of enantiopure 3,6-dihydro-2H-pyrans is presented. The addition of lithiated enol ethers to carbohydrate-derived nitrones afforded syn- or anti-configured hydroxylamine derivatives 4a–d that were cyclized under Lewis acidic conditions to yield functionalized dihydropyrans cis- or trans-5a–d containing an enol ether moiety. This functional group was employed for a variety of subsequent reactions such as dihydroxylation or bromination. Bicyclic enol ether 19 was oxidatively cleaved to provide the highly functionalized ten-membered ring lactone 20. The synthesized enantiopure aminopyrans 24, 26, 28 and 30 can be regarded as carbohydrate mimetics. Trimeric versions of 24 and 28 were constructed via their attachment to a tricarboxylic acid core.

Gold-catalyzed generation of vinylthionium ions and the development of an organocatalytic, asymmetric (4+3)-cycloaddition reaction

2017 ◽  
Author(s):  
◽  
Michael Topinka
Keyword(s):  
Amino Alcohol ◽  
Good Yield ◽  
Lewis Acids ◽  
Cycloaddition Reaction ◽  
Unsaturated Ester ◽  
Cycloaddition Reactions ◽  
University Of Missouri ◽  
Considerable Problem ◽  
The University ◽  
Substituted Furans

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] An allylic benzoate ester was prepared and used as a progenitor of vinylthionium ions for (4+3)-cycloaddition reactions. The chemistry was limited to 2-substituted and 2,5-disubstituted furans. In the case of 2-substituted furans, only Friedel-Crafts alkylation products were procured. In the case of 2,5-disubstituted furans, (4+3)-cycloaddition products were furnished in good yield. A catalytic, asymmetric variant using 2,5-dialkylfurans and chiral acids to procure cycloaddition products was unsuccessful. There was an opportunity to overcome the Friedel-Crafts alkylation problem that arose in a gold-catalyzed cycloaddition project. A sulfur-substituted unsaturated ester and alcohol were prepared, but silyl migration was a considerable problem upon activation by various agents. The problem of silyl migration was circumvented, but the target aldehyde was unreactive toward dienes in the presence of various Lewis acids. In further pursuit of an asymmetric (4+3)-cycloaddition reaction, 2-substituted furans were reacted with 2-tosyloxycyclopentanone in the presence of K2HPO4/H2O in perfluorobenzene as solvent and 30 mol% of an amino alcohol catalyst developed by David MacMillan. Enantioselectivities were modest for 2-alkylfurans and excellent for 2-arylchalcogenofurans (90% ee). 3-Substituted furans also work in this process.

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