scholarly journals Aryne,ortho-Quinone Methide, andortho-Quinodimethane: Synthesis of Multisubstituted Arenes Using the Aromatic Reactive Intermediates

2010 ◽  
Vol 83 (3) ◽  
pp. 199-219 ◽  
Author(s):  
Hiroto Yoshida ◽  
Joji Ohshita ◽  
Atsutaka Kunai
Keyword(s):  
Reactive Intermediates ◽  
Quinone Methide

[4+n] Annulation Reactions Using ortho-Halomethyl Anilines as Aza-ortho-Quinone Methide Precursors

Synthesis ◽  
2021 ◽  
Author(s):  
Xiao-Yu He ◽  
Yu-Hong Ma ◽  
Qing-Qing Yang ◽  
Wen-Jing Xiao
Keyword(s):  
Convenient Method ◽  
Reactive Intermediates ◽  
Quinone Methide ◽  
Synthetic Chemistry ◽  
Important Class ◽  
Quinone Methides ◽  
Aniline Derivatives

Aza-ortho-quinone methides are an important class of reactive intermediates, which have found broad applications in synthetic chemistry. Recently, 1,4-elimination of ortho-halomethyl aniline derivatives has emerged as a new powerful and convenient method for aza-ortho-quinone methide generation. This review will highlight their recent applications as aza-ortho-quinone methide precursors in annulation reactions to access various biologically important nitrogen-containing heterocycles. The general mechanisms are briefly discussed as well.

Biocatalyst-Initiated Ortho-Quinone Methide Formation and Derivatization

2019 ◽  
Author(s):  
Tyler Doyon ◽  
Jonathan Perkins ◽  
Summer A. Baker Dockrey ◽  
Kevin Skinner ◽  
Paul M. Zimmerman ◽  
...  
Keyword(s):  
Reactive Intermediates ◽  
Heme Iron ◽  
Quinone Methide ◽  
Reaction Conditions ◽  
One Pot ◽  
Mild Conditions ◽  
Non Heme Iron ◽  
Common Strategy ◽  
Aqueous Conditions ◽  
Ortho Cresol

Generation of reactive intermediates and interception of these fleeting species in a cascade is a common strategy employed by Nature. However, formation of these species under mild conditions using traditional synthetic techniques can present a challenge. Here, we demonstrate the utility of biocatalysis in generating ortho-quinone methide intermediates under aqueous conditions and at reduced temperatures. Specifically, we applied an α-ketoglutarate-dependent non-heme iron enzyme, CitB, in the selective modification of benzylic C–H bonds of ortho-cresol substrates to afford a benzylic alcohol product which, under the reaction conditions, is in equilibrium with the corresponding ortho-quinone methide. Interception of the ortho-quinone methide by a nucleophile or a dienophile allows for one-pot conversion of benzylic C–H bonds into C–C, C–N, C–O, and C–S bonds in a chemoenzymatic cascade.

Quinone methide intermediates in organic photochemistry

2001 ◽  
Vol 73 (3) ◽  
pp. 529-534 ◽  
Author(s):  
Peter Wan ◽  
Darryl W. Brousmiche ◽  
Christy Z. Chen ◽  
John Cole ◽  
Matthew Lukeman ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Excited States ◽  
Recent Progress ◽  
Reactive Intermediates ◽  
Intramolecular Proton Transfer ◽  
Quinone Methide ◽  
Mechanism Of Formation ◽  
Quinone Methides ◽  
Structural Types ◽  
Related Compounds

Quinone methides are widely encountered reactive intermediates in the chemistry of phenols and related compounds. This paper summarizes our recent progress in uncovering new and general photochemical methods for forming quinone methides of various structural types in aqueous solution. Their mechanism of formation and subsequent chemistry are also discussed. New examples of excited-state intramolecular proton transfer (ESIPT) have been uncovered in these studies. We have also discovered that appropriately designed biphenyls and terphenyls display photochemistry that is best rationalized by highly polarized and planar excited states of these ring systems, which can efficiently lead to the corresponding extended quinone methides.

ortho-Quinone methide (o-QM): a highly reactive, ephemeral and versatile intermediate in organic synthesis

RSC Advances ◽  
2014 ◽  
Vol 4 (99) ◽  
pp. 55924-55959 ◽  
Author(s):  
Maya Shankar Singh ◽  
Anugula Nagaraju ◽  
Namrata Anand ◽  
Sushobhan Chowdhury
Keyword(s):  
Organic Synthesis ◽  
Critical Review ◽  
Reactive Intermediates ◽  
Quinone Methide ◽  
Quinone Methides ◽  
Comprehensive View

In this critical review, we provide a comprehensive view of the chemistry of ortho-quinone methides as versatile reactive intermediates in organic synthesis.

scholarly journals Reactive intermediates. Some chemistry of quinone methides

2000 ◽  
Vol 72 (12) ◽  
pp. 2299-2308 ◽  
Author(s):  
Y. Chiang ◽  
A. J. Kresge ◽  
Y. Zhu
Keyword(s):  
Acid Catalysis ◽  
Isotope Effects ◽  
Reactive Intermediates ◽  
Quinone Methide ◽  
Carbonyl Carbon Atom ◽  
Carbonyl Carbon ◽  
Quinone Methides ◽  
Rate Determining Step ◽  
Energy Relationships ◽  
Acid Catalyzed

Quinone methides were produced in aqueous solution by photochemical dehydration of o-hydroxybenzyl alcohols (o-HOC6H4CHROH; R = H, C6H5, 4-CH3OC6H4), and flash photolytic techniques were used to examine their rehydration back to starting substrate as well as their interaction with bromide and thiocyanate ions. These reactions are acid-catalyzed and show inverse isotope effects (kH+/kD+ < 1), indicating that they occur through preequilibrium protonation of the quinone methide on its carbonyl carbon atom followed by rate-determining capture of the benzyl carbocations so formed by H2O, Br-, or SCN-. With some quinone methides (R = C6H5 and 4-CH3OC6H4) this acid catalysis could be saturated, and analysis of the data obtained in the region of saturation for the example with R = 4-CH3OC6H4 produced both the equilibrium constant for the substrate protonation step and the rate constant for the rate-determining step. Energy relationships comparing the quinone methides with their benzyl alcohol precursors are derived.

scholarly journals Oxidative Transformations of 3,4-Dihydroxyphenylacetaldehyde Generate Potential Reactive Intermediates as Causative Agents for Its Neurotoxicity

2021 ◽  
Vol 22 (21) ◽  
pp. 11751
Author(s):  
Shosuke Ito ◽  
Hitomi Tanaka ◽  
Makoto Ojika ◽  
Kazumasa Wakamatsu ◽  
Manickam Sugumaran
Keyword(s):  
Oxidation Product ◽  
Oxidation Reaction ◽  
Reactive Intermediates ◽  
Quinone Methide ◽  
Toxic Metabolite ◽  
Mushroom Tyrosinase ◽  
Toxic Compounds ◽  
Causative Agents ◽  
Oxidative Transformations ◽  
Aldehyde Groups

Neurogenerative diseases, such as Parkinson’s disease, are associated, not only with the selective loss of dopamine (DA), but also with the accumulation of reactive catechol-aldehyde, 3,4-dihydroxyphenylacetaldehyde (DOPAL), which is formed as the immediate oxidation product of cytoplasmic DA by monoamine oxidase. DOPAL is well known to exhibit toxic effects on neuronal cells. Both catecholic and aldehyde groups seem to be associated with the neurotoxicity of DOPAL. However, the exact cause of toxicity caused by this compound remains unknown. Since the reactivity of DOPAL could be attributed to its immediate oxidation product, DOPAL-quinone, we examined the potential reactions of this toxic metabolite. The oxidation of DOPAL by mushroom tyrosinase at pH 5.3 produced conventional DOPAL-quinone, but oxidation at pH 7.4 produced the tautomeric quinone-methide, which gave rise to 3,4-dihydroxyphenylglycolaldehyde and 3,4-dihydroxybenzaldehyde as products through a series of reactions. When the oxidation reaction was performed in the presence of ascorbic acid, two additional products were detected, which were tentatively identified as the cyclized products, 5,6-dihydroxybenzofuran and 3,5,6-trihydroxybenzofuran. Physiological concentrations of Cu(II) ions could also cause the oxidation of DOPAL to DOPAL-quinone. DOPAL-quinone exhibited reactivity towards the cysteine residues of serum albumin. DOPAL-oligomer, the oxidation product of DOPAL, exhibited pro-oxidant activity oxidizing GSH to GSSG and producing hydrogen peroxide. These results indicate that DOPAL-quinone generates several toxic compounds that could augment the neurotoxicity of DOPAL.

scholarly journals Chemoenzymatic ortho-quinone methide formation

2019 ◽  
Author(s):  
Tyler Doyon ◽  
Jonathan Perkins ◽  
Summer A. Baker Dockrey ◽  
Evan O. Romero ◽  
Kevin Skinner ◽  
...  
Keyword(s):  
Reactive Intermediates ◽  
Heme Iron ◽  
Quinone Methide ◽  
Reaction Conditions ◽  
One Pot ◽  
Mild Conditions ◽  
Non Heme Iron ◽  
Common Strategy ◽  
Aqueous Conditions ◽  
Ortho Cresol

Generation of reactive intermediates and interception of these fleeting species in a cascade is a common strategy employed by Nature. However, formation of these species under mild conditions using traditional synthetic techniques can present a challenge. Here, we demonstrate the utility of biocatalysis in generating ortho-quinone methide intermediates under aqueous conditions and at reduced temperatures. Specifically, we applied an α-ketoglutarate-dependent non-heme iron enzyme, CitB, in the selective modification of benzylic C–H bonds of ortho-cresol substrates to afford a benzylic alcohol product which, under the reaction conditions, is in equilibrium with the corresponding ortho-quinone methide. Interception of the ortho-quinone methide by a nucleophile or a dienophile allows for one-pot conversion of benzylic C–H bonds into C–C, C–N, C–O, and C–S bonds in a chemoenzymatic cascade.

Biocatalyst-Initiated Ortho-Quinone Methide Formation and Derivatization

2019 ◽  
Author(s):  
Tyler Doyon ◽  
Jonathan Perkins ◽  
Summer A. Baker Dockrey ◽  
Kevin Skinner ◽  
Paul M. Zimmerman ◽  
...  
Keyword(s):  
Reactive Intermediates ◽  
Heme Iron ◽  
Quinone Methide ◽  
Reaction Conditions ◽  
One Pot ◽  
Mild Conditions ◽  
Non Heme Iron ◽  
Common Strategy ◽  
Aqueous Conditions ◽  
Ortho Cresol

Generation of reactive intermediates and interception of these fleeting species in a cascade is a common strategy employed by Nature. However, formation of these species under mild conditions using traditional synthetic techniques can present a challenge. Here, we demonstrate the utility of biocatalysis in generating ortho-quinone methide intermediates under aqueous conditions and at reduced temperatures. Specifically, we applied an α-ketoglutarate-dependent non-heme iron enzyme, CitB, in the selective modification of benzylic C–H bonds of ortho-cresol substrates to afford a benzylic alcohol product which, under the reaction conditions, is in equilibrium with the corresponding ortho-quinone methide. Interception of the ortho-quinone methide by a nucleophile or a dienophile allows for one-pot conversion of benzylic C–H bonds into C–C, C–N, C–O, and C–S bonds in a chemoenzymatic cascade.

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