Oxidation with a “Stopover” – Stable Zwitterions as Intermediates in the Oxidation of α‐Tocopherol (Vitamin E) Model Compounds to their Corresponding ortho‐Quinone Methides
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DOI: 10.1002/open.202000306
Abstract: Abstract As a prominent member of the vitamin E group, α‐tocopherol is an important lipophilic antioxidant. It has a special oxidation chemistry that involves phenoxyl radicals, quinones and quinone methides. During the oxidation to the… read more here.
Keywords: quinone methide; oxidation; quinone methides; rotation ... See more keywords
Synthesis of symmetrical chromeno[2,3-b]chromenes on the basis of о-quinone methides and 1,1-bis(morpholino)ethene
Sign Up to like & getrecommendations! Published in 2017 at "Chemistry of Heterocyclic Compounds"
DOI: 10.1007/s10593-018-2211-4
Abstract: The reaction of 1,1-bis(morpholino)ethene with precursors of о-quinone methides derived from Mannich bases of phenols and 2-naphthols provided a series of chromeno[2,3-b]chromenes. The cascade process included a hetero-Diels–Alder reaction between о-quinone methide and ketenaminal, elimination… read more here.
Keywords: quinone methides; quinone; morpholino ethene; bis morpholino ... See more keywords
1,6-Aza-Michael addition of para-quinone methides with N-heterocycles catalyzed by Zn(OTf)2: A regioselective approach to N-diarylmethyl-substituted heterocycles
Sign Up to like & getrecommendations! Published in 2020 at "Tetrahedron"
DOI: 10.1016/j.tet.2020.131338
Abstract: Abstract An efficient Zn(OTf)2-catalyzed regioselective C–N bond making reaction between a bunch of aryl/heteroaryl-substituted para-quinone methides as ideal 1,6-acceptors and various aromatic/non-aromatic aza-heterocycles bearing N–H moiety namely carbazoles, pyrazoles, indazole, benzotriazole and saccharin is reported.… read more here.
Keywords: quinone methides; michael addition; para quinone; diarylmethyl substituted ... See more keywords
1,6-Conjugate sulfonylation of para-quinone methides: An expedient approach to unsymmetrical gem-diarylmethyl sulfones
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DOI: 10.1016/j.tetlet.2018.12.023
Abstract: Abstract A novel sulfonylation of para -quinone methides with sodium arylsulfinates has been developed via acetic acid promoted sulfa-Michael addition. This reaction provides an inexpensive and efficient method to synthesize various unsymmetrical diarylmethyl sulfones, displaying… read more here.
Keywords: sulfonylation para; para quinone; quinone methides; diarylmethyl sulfones ... See more keywords
Lignin-Biosynthetic Study: Reactivity of Quinone Methides in the Diastereopreferential Formation of p-Hydroxyphenyl- and Guaiacyl-Type β- O-4 Structures.
Sign Up to like & getrecommendations! Published in 2019 at "Journal of agricultural and food chemistry"
DOI: 10.1021/acs.jafc.8b06465
Abstract: p-Quinone methides are involved in lignin biosynthesis as transient intermediates, and the aromatization step has a great impact on the chemical structure of the resulting lignin. A series of quinone methides (QMs) were synthesized and… read more here.
Keywords: qms; quinone methides; type qms; formation hydroxyphenyl ... See more keywords
Harnessing ortho-Quinone Methides in Natural Product Biosynthesis and Biocatalysis.
Sign Up to like & getrecommendations! Published in 2022 at "Journal of natural products"
DOI: 10.1021/acs.jnatprod.1c01026
Abstract: The implementation of ortho-quinone methide (o-QM) intermediates in complex molecule assembly represents a remarkably efficient strategy designed by Nature and utilized by synthetic chemists. o-QMs have been taken advantage of in biomimetic syntheses for decades,… read more here.
Keywords: quinone methides; harnessing ortho; methides natural; product ... See more keywords
Enantioselective 1,6-Addition of β-Ketoester Enolates to In Situ Generated para-Quinone Methides Enabled by Cooperative Palladium and Brønsted Acid Catalysis.
Sign Up to like & getrecommendations! Published in 2023 at "Organic letters"
DOI: 10.1021/acs.orglett.2c04127
Abstract: We report herein an asymmetric cooperative process for the enantioselective 1,6-addition of β-ketoesters to in situ generated para-quinone methides with chiral Pd-aqua complexes as mixed Brønsted acid-base catalysts. Excellent yields, outstanding enantiocontrol, and good diastereoselectivity… read more here.
Keywords: situ generated; generated para; para quinone; quinone methides ... See more keywords
Bismuth(III)-Catalyzed 1,8-Addition/Cyclization/Rearrangement of Propargylic para-Quinone Methides with 2-Vinylphenol: Synthesis of Indeno[2,1-c]chromenes.
Sign Up to like & getrecommendations! Published in 2023 at "Organic letters"
DOI: 10.1021/acs.orglett.3c00179
Abstract: The unique reactivity of in situ generated propargylic para-quinone methides as a new type of five-carbon synthon has been discovered by a novel bismuth(III)-catalyzed tandem annulation reaction. This 1,8-addition/cyclization/rearrangement cyclization cascade reaction is characterized by… read more here.
Keywords: para quinone; quinone methides; cyclization; bismuth iii ... See more keywords
Cascade Radical 1,6-Addition/Cyclization of para-Quinone Methides: Leading to Spiro[4.5]deca-6,9-dien-8-ones.
Sign Up to like & getrecommendations! Published in 2018 at "Organic letters"
DOI: 10.1021/acs.orglett.8b00518
Abstract: A cascade three-component iodoazidation of para-quinone methides to construct spiro[4.5]deca-6,9-dien-8-ones under mild conditions has been developed. The chemoselective 1,6-addition of azide radical triggered a regioselective 5-exo-dig cyclization/radical coupling sequence, enabling C-N, C-C, and C-I bond… read more here.
Keywords: spiro deca; quinone methides; dien ones; para quinone ... See more keywords
Phosphoric Acid Catalyzed Aldehyde Addition to in Situ Generated o-Quinone Methides: An Enantio- and Diastereoselective Entry toward cis-3,4-Diaryl Dihydrocoumarins.
Sign Up to like & getrecommendations! Published in 2018 at "Organic letters"
DOI: 10.1021/acs.orglett.8b01865
Abstract: A highly stereoselective, phosphoric acid catalyzed synthesis of cis-3,4-diarylchromanols through reaction of o-hydroxybenzhydryl alcohols and aryl acetaldehydes is reported. The products can be further manipulated to 3,4-dihydrocoumarins, 4 H-chromenes, and chromanes with good overall yields… read more here.
Keywords: cis; quinone methides; aldehyde addition; phosphoric acid ... See more keywords
Visible-Light-Triggered Cyanoalkylation of para-Quinone Methides and Its Application to the Synthesis of GPR40 Agonists.
Sign Up to like & getrecommendations! Published in 2019 at "Organic letters"
DOI: 10.1021/acs.orglett.9b01325
Abstract: Cyanoalkylated diarylmethanes with biological and pharmacological potentials were synthesized from para-quinone methides and cyanoalkylating reagents through a photocatalytic process. This protocol is operationally simple and mild and has high efficiency, which gave the corresponding products… read more here.
Keywords: gpr40 agonists; synthesis gpr40; para quinone; quinone methides ... See more keywords