Quinone methides?and not dehydrodopamine derivatives?as reactive intermediates of ?-sclerotization in the puparia of flesh flySarcophaga bullata

1988 ◽  
Vol 8 (2) ◽  
pp. 73-88 ◽  
Author(s):  
Manickam Sugumaran
Keyword(s):  
Reactive Intermediates ◽  
Quinone Methides

[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.

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.

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