scholarly journals Mannich base-connected syntheses mediated by ortho-quinone methides

2018 ◽  
Vol 14 ◽  
pp. 560-575 ◽  
Author(s):  
Petra Barta ◽  
Ferenc Fülöp ◽  
István Szatmári
Keyword(s):  
Biological Activity ◽  
Mannich Base ◽  
Quinone Methide ◽  
Cycloaddition Reactions ◽  
Quinone Methides ◽  
Pharmacological Activities ◽  
Mannich Reactions

This article provides an overview about specifically modified Mannich reactions where the process involves an ortho-quinone methide (o-QM) intermediate. The reactions are classified on the basis of the o-QM source followed by the reactant, e.g., the dienophile partner in cycloaddition reactions (C=C or C=N dienophiles) or by the formation of multicomponent Mannich adducts. Due to the important pharmacological activities of these reactive o-QM intermediates, special attention is paid to the biological activity of these compounds.

Reactions of 2-phenyl-4H-1,3,2-benzodioxaborin, a stable ortho-quinone methide precursor

1992 ◽  
Vol 70 (6) ◽  
pp. 1717-1732 ◽  
Author(s):  
Jeffrey D. Chambers ◽  
Jason Crawford ◽  
Haydn W. R. Williams ◽  
Claude Dufresne ◽  
John Scheigetz ◽  
...  
Keyword(s):  
Vinyl Ether ◽  
Lewis Acid ◽  
Quinone Methide ◽  
Ethyl Vinyl Ether ◽  
Cycloaddition Reactions ◽  
Substituted Phenols ◽  
Quinone Methides ◽  
Ethyl Vinyl ◽  
Aryl Group ◽  
Intramolecular Reaction

Thermolysis of 1-phenyl-4H-1,3,2-benzodioxaborins generated the corresponding ortho-quinone methides, which were found to undergo intermolecular cycloaddition reactions with ethyl vinyl ether, dihydropyran, β-methylstyrene, cyclohexene, and 1-ethoxy-1-z-trimethylsiloxy-1-propenes to give various substituted chromans. Intramolecular trapping of the quinone methides with an olefin led to the syntheses of several analogs of tetrahydrocannabinols. ortho-Quinone methides, generated by treatment of the 2-phenyl-4H-1,3,2-benzodioxaborins with a Lewis acid, react with various nucleophiles to give the corresponding 1,4-addition products. Thus, alkyl and aryl thiols, alcohols, amine, hydride, allyl trimethylsilane, acetophenone, and diethylmalonate as well as some aryl compounds react with the quinone methide to give various 2-substituted phenols. Intramolecular reaction of the quinone methide with an aryl group led to the preparation of some 4-phenylchromans and tetralins.

Flavones and Their Analogues as Bioactive Compounds – An Overview

2019 ◽  
Vol 16 (4) ◽  
pp. 377-391 ◽  
Author(s):  
B.S. Jayashree ◽  
H. Venkatachalam ◽  
Sanchari Basu Mallik
Keyword(s):  
Biological Activity ◽  
Free Radical ◽  
Bioactive Compounds ◽  
Antioxidant Properties ◽  
Radical Scavenging ◽  
Cost Effective ◽  
Free Radical Scavenging ◽  
Polyphenolic Compounds ◽  
Pharmacological Activities ◽  
Poor Solubility

Flavonoids constitute a large group of polyphenolic compounds that are known to have antioxidant properties, through their free radical scavenging abilities. They possess a chromone (γ- benzopyrone) moiety, responsible for eliciting many pharmacological activities. Even though, natural flavonoids are highly potent, owing to their poor solubility, they are less used. Therefore, attempts have been made to improve their stability, solubility, efficacy and kinetics by introducing various substituents on the flavone ring. For nearly the last two decades, flavones were synthesized in our laboratory by simple, convenient and cost-effective methods, with the knowledge of both synthetic and semi-synthetic chemistry. In this direction, it was considered worthwhile to present an overview on the synthesized flavonoids. This review creates a platform for highlighting various modifications done on the flavone system along with their biological activity.

scholarly journals Chemical Diversity and Biological Activity of Secondary Metabolites from Soft Coral Genus Sinularia since 2013

Marine Drugs ◽  
2021 ◽  
Vol 19 (6) ◽  
pp. 335
Author(s):  
Xia Yan ◽  
Jing Liu ◽  
Xue Leng ◽  
Han Ouyang
Keyword(s):  
Biological Activity ◽  
Secondary Metabolites ◽  
Coral Species ◽  
Soft Coral ◽  
Biological Activities ◽  
Vital Role ◽  
Chemical Diversity ◽  
Pharmacological Activities ◽  
Lead Compounds ◽  
Coral Genus

Sinularia is one of the conspicuous soft coral species widely distributed in the world’s oceans at a depth of about 12 m. Secondary metabolites from the genus Sinularia show great chemical diversity. More than 700 secondary metabolites have been reported to date, including terpenoids, norterpenoids, steroids/steroidal glycosides, and other types. They showed a broad range of potent biological activities. There were detailed reviews on the terpenoids from Sinularia in 2013, and now, it still plays a vital role in the innovation of lead compounds for drug development. The structures, names, and pharmacological activities of compounds isolated from the genus Sinularia from 2013 to March 2021 are summarized in this review.

scholarly journals Recent advances and prospects in the Zn-catalysed Mannich reaction

RSC Advances ◽  
2021 ◽  
Vol 11 (16) ◽  
pp. 9098-9111
Author(s):  
Salahudeen Shamna ◽  
C. M. A. Afsina ◽  
Rose Mary Philip ◽  
Gopinathan Anilkumar
Keyword(s):  
Carbonyl Compound ◽  
Secondary Amine ◽  
Mannich Reaction ◽  
Mannich Base ◽  
Mannich Reactions ◽  
Recent Advances ◽  
Primary Secondary Amine

Amino alkylation of an acidic α-proton of a carbonyl by formaldehyde and a primary/secondary amine or ammonia, affording a β-amino-carbonyl compound also known as a Mannich base is a valuable reaction. We focus on recent advances in Zn catalysed Mannich reactions.

scholarly journals Curcumin and Its Potential Impact on Microbiota

Nutrients ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 2004
Author(s):  
Marzena Jabczyk ◽  
Justyna Nowak ◽  
Bartosz Hudzik ◽  
Barbara Zubelewicz-Szkodzińska
Keyword(s):  
Biological Activity ◽  
Gut Microbiota ◽  
Health Effects ◽  
Pharmacokinetic Profile ◽  
Health Impact ◽  
Pharmacological Activities ◽  
Poor Solubility ◽  
Potential Impact ◽  
Bidirectional Interactions

Curcumin is one of the most frequently researched herbal substances; however, it has been reported to have a poor bioavailability and fast metabolism, which has led to doubts about its effectiveness. Curcumin has antioxidant and anti-inflammatory effects, and has demonstrated favorable health effects. Nevertheless, well-reported in vivo pharmacological activities of curcumin are limited by its poor solubility, bioavailability, and pharmacokinetic profile. The bidirectional interactions between curcumin and gut microbiota play key roles in understanding the ambiguity between the bioavailability and biological activity of curcumin, including its wider health impact.

scholarly journals Photochemical Reactivity of Naphthol-Naphthalimide Conjugates and Their Biological Activity

Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3355
Author(s):  
Matija Sambol ◽  
Patricia Benčić ◽  
Antonija Erben ◽  
Marija Matković ◽  
Branka Mihaljević ◽  
...  
Keyword(s):  
Biological Activity ◽  
Rational Design ◽  
Human Cancer ◽  
Photophysical Properties ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Quinone Methide ◽  
Quantum Yields ◽  
Photochemical Reactivity ◽  
Human Cancer Cell Lines

Quinone methide precursors 1a–e, with different alkyl linkers between the naphthol and the naphthalimide chromophore, were synthesized. Their photophysical properties and photochemical reactivity were investigated and connected with biological activity. Upon excitation of the naphthol, Förster resonance energy transfer (FRET) to the naphthalimide takes place and the quantum yields of fluorescence are low (ΦF ≈ 10−2). Due to FRET, photodehydration of naphthols to QMs takes place inefficiently (ΦR ≈ 10−5). However, the formation of QMs can also be initiated upon excitation of naphthalimide, the lower energy chromophore, in a process that involves photoinduced electron transfer (PET) from the naphthol to the naphthalimide. Fluorescence titrations revealed that 1a and 1e form complexes with ct-DNA with moderate association constants Ka ≈ 105–106 M−1, as well as with bovine serum albumin (BSA) Ka ≈ 105 M−1 (1:1 complex). The irradiation of the complex 1e@BSA resulted in the alkylation of the protein, probably via QM. The antiproliferative activity of 1a–e against two human cancer cell lines (H460 and MCF 7) was investigated with the cells kept in the dark or irradiated at 350 nm, whereupon cytotoxicity increased, particularly for 1e (>100 times). Although the enhancement of this activity upon UV irradiation has no imminent therapeutic application, the results presented have importance in the rational design of new generations of anticancer phototherapeutics that absorb visible light.

Biological Activity of Novel N-Substituted Amides of endo-3- (3-Methylthio-1,2,4-triazol-5-yl)bicyclo[2.2.1]hept-5-ene-2- carboxylic Acid and N-Substituted Amides of 1-(5-Methylthio- 1,2,4-triazol-3-yl)cyclohexane-2-carboxylic Acids

2012 ◽  
Vol 67 (3-4) ◽  
pp. 123-128
Author(s):  
Anna Pachuta-Stec ◽  
Urszula Kosikowska ◽  
Anna Chodkowska ◽  
Monika Pitucha ◽  
Anna Malm ◽  
...  
Keyword(s):  
Biological Activity ◽  
Carboxylic Acid ◽  
Carboxylic Acids ◽  
Condensation Reaction ◽  
Primary Amines ◽  
Pharmacological Activities

N-Substituted amides of endo-3-(3-methylthio-1,2,4-triazol-5-yl)bicyclo[2.2.1]hept-5-ene- 2-carboxylic acid and 1-(5-methylthio-1,2,4-triazol-3-yl)cyclohexane-2-carboxylic acid were prepared by the condensation reaction of endo-S-methyl-N1-(bicyclo[2.2.1]hept-5-ene-2,3- dicarbonyl)isothiosemicarbazide and S-methyl-N1-(cyclohexane-2,3-dicarbonyl)isothiosemicarbazide with primary amines. The synthesized compounds were screened for their microbiological and pharmacological activities

A New Cycloaddition Profile for ortho-Quinone Methides: Photoredox-Catalyzed [6+4] Cycloadditions for Synthesis of Benzo[b]cyclopenta[e]oxepines

2022 ◽  
Author(s):  
Kenta Tanaka ◽  
Yosuke Asada ◽  
Yujiro Hoshino
Keyword(s):  
Visible Light ◽  
Cycloaddition Reactions ◽  
Quinone Methides

Visible-light-induced [6+4] cycloaddition reactions of ortho-quinone methides have been developed. The reaction of ortho-quinone methides with pentafulvenes in the presence of a thioxanthylium photoredox catalyst afforded benzo[b]cyclopenta[e]oxepines. The present reaction...

A new dehydrogenative [4 + 1] annulation between para-quinone methides (p-QMs) and iodonium ylides for the synthesis of 2,3-dihydrobenzofurans

2018 ◽  
Vol 5 (23) ◽  
pp. 3483-3487 ◽  
Author(s):  
Yan-Jie Xiong ◽  
Shao-Qing Shi ◽  
Wen-Juan Hao ◽  
Shu-Jiang Tu ◽  
Bo Jiang
Keyword(s):  
Quinone Methide ◽  
Quinone Methides ◽  
Iodonium Ylides

A new dehydrogenative [4 + 1] annulation of para-quinone methides (p-QMs) with acyclic and cyclic iodonium ylides has been established, delivering a variety of functionalized 2,3-dihydrobenzofurans with the retention of the quinone methide unit in generally good yields.

Solvolysis and ring closure of quinone methides photogenerated from biaryl systems

2005 ◽  
Vol 83 (9) ◽  
pp. 1306-1323 ◽  
Author(s):  
Yijian Shi ◽  
Peter Wan
Keyword(s):  
Ring Closure ◽  
Quinone Methide ◽  
High Yield ◽  
Nanosecond Laser ◽  
Quinone Methides ◽  
Molecular Mechanics Calculations ◽  
Fluorescence Studies ◽  
Long Wavelength ◽  
Thermal Chemistry ◽  
Nanosecond Laser Photolysis

A variety of biaryl quinone methides have been photogenerated with a range of efficiencies from biaryl precursors 4–6 and 8, 10, and 11, all having hydroxyl and hydroxymethyl substituents on alternate rings. These novel biaryl quinone methides, which cannot be readily generated via thermal chemistry, are trapped by added nucleophiles such as MeOH and ethanolamine; two that cannot undergo electrocyclic ring closure (from 8 and 11) are readily observable by nanosecond laser photolysis, with long wavelength maxima (λmax) of 600 and 520 nm, respectively. Photogenerated o,o′-biaryl quinone methides undergo electrocyclic ring closure to give the corresponding chromene (pyran) products in high yield. Since the precursor biaryl alcohols have highly twisted structures in the ground state (dihedral angle of up to 90° by molecular mechanics calculations), a significant twisting motion to planarity is required to achieve reaction. Using steady-state fluorescence studies, we present evidence to suggest that the mechanism of quinone methide formation may occur via one of the following mechanisms: (i) dissociation of the proton from ArOH that precedes twisting; or (ii) ArOH dissociation and twisting taking place either simultaneously or in quick succession.Key words: biaryl quinone methide, photosolvolysis, photodeprotonation, photocyclization.

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