Brønsted acid catalyzed radical addition to quinone methides

2021 ◽  
Author(s):  
Shiv Shankar Patel ◽  
Dileep Kumar ◽  
Chandra Bhushan Tripathi
Keyword(s):  
Alkyl Radical ◽  
Acid Catalysis ◽  
Radical Addition ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Quinone Methides ◽  
Mild Conditions ◽  
Brönsted Acid ◽  
Acid Catalyzed ◽  
Radical Generation

A fundamental quest for alkyl radical generation under mild conditions through photoinduced Brønsted acid catalysis is addressed.

Brønsted acid-catalyzed 1,2-fluorine migration with fluoroepoxides

2015 ◽  
Vol 44 (45) ◽  
pp. 19636-19641 ◽  
Author(s):  
Tao Luo ◽  
Rui Zhang ◽  
Xiao Shen ◽  
Wei Zhang ◽  
Chuanfa Ni ◽  
...  
Keyword(s):  
Fluorine Atom ◽  
Acid Catalysis ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Atom Economy ◽  
Mild Conditions ◽  
Brönsted Acid ◽  
Acid Catalyzed ◽  
Bronsted Acid Catalysis

An efficient 1,2-fluorine migration reaction was realized under Brønsted acid catalysis in the absence of an external fluorinating source. The high fluorine atom economy and very mild conditions make this reaction a promising protocol for the construction of the C–F bond.

Brønsted Acid Catalyzed Domino 1,6-Addition/Intramolecular Cyclization­ Reactions: Diastereoselective Synthesis of Dihydro­coumarin Frameworks

Synthesis ◽  
2017 ◽  
Vol 50 (06) ◽  
pp. 1307-1314 ◽  
Author(s):  
Guang-Jian Mei ◽  
Zheng Cao ◽  
Gui-Xiang Zhou ◽  
Chun Ma ◽  
Kang Jiang
Keyword(s):  
Hydrogen Bonding ◽  
Crucial Role ◽  
Acid Catalysis ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Diastereoselective Synthesis ◽  
Quinone Methides ◽  
Hydrogen Bonding Interactions ◽  
Brönsted Acid ◽  
Acid Catalyzed

An efficient domino 1,6-addition/intramolecular cyclization reaction between para-quinone methides (p-QMs) and azlactones under Brønsted acid catalysis was established. A series of highly functionalized dihydrocoumarins were constructed in good to excellent yields (up to 96%) with excellent diastereoselectivities (all >20:1 d.r.). In this process, the Brønsted acid plays a crucial role not only in activating the two substrates, but also in controlling the diastereoselectivity of the reaction via hydrogen-bonding interactions. In addition, this protocol demonstrates the great practicability of utilizing p-QMs in domino reactions.

Efficient Synthesis of Chromenes from Vinyl o-Quinone Methides via a Brønsted Acid Catalyzed Electrocyclization Process

Synthesis ◽  
2018 ◽  
Vol 50 (12) ◽  
pp. 2416-2422 ◽  
Author(s):  
Man-Su Tu ◽  
Guang-Jian Mei ◽  
Feng Shi ◽  
Si-Jia Liu ◽  
Xiao-Li Jiang ◽  
...  
Keyword(s):  
Efficient Method ◽  
Research Area ◽  
Environmentally Benign ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Efficient Synthesis ◽  
Quinone Methides ◽  
Efficient Approach ◽  
Brönsted Acid ◽  
Acid Catalyzed

An efficient approach for the synthesis of chromene derivatives from vinyl o-quinone methides was established via a Brønsted acid catalyzed electrocyclization. By using this methodology, a series of structurally diversified chromenes was synthesized in a highly atom-economic and environmentally benign manner with generally good to excellent yields (up to 98% yield). This reaction will not only provide an efficient method for the construction of chromene scaffolds, but also enrich the research area of o-quinone methides.

Organic Photoredox Catalytic α-C(sp3)–H Phosphorylation of Saturated Aza-Heterocycles

2021 ◽  
Author(s):  
Ming-Jun Yi ◽  
Teng-Fei Xiao ◽  
Wen-Hui Li ◽  
Yi-Fan Zhang ◽  
Pen-Ji Yan ◽  
...  
Keyword(s):  
Acid Catalysis ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Metal Free ◽  
Mild Conditions ◽  
Brönsted Acid ◽  
Bronsted Acid Catalysis

A metal-free C(sp3)–H phosphorylation of saturated aza-heterocycles via the merger of organic photoredox and Brønsted acid catalysis was established under mild conditions. This protocol provided a straightforward and economic access...

An uncommon use of irradiated flavins: Brønsted acid catalysis

2020 ◽  
Vol 56 (42) ◽  
pp. 5661-5664
Author(s):  
Yukihiro Arakawa ◽  
Tomohiro Mihara ◽  
Hiroki Fujii ◽  
Keiji Minagawa ◽  
Yasushi Imada
Keyword(s):  
Visible Light ◽  
Visible Light Irradiation ◽  
Acid Catalysis ◽  
Light Irradiation ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Mild Conditions ◽  
Brönsted Acid ◽  
Bronsted Acid Catalysis

Visible light irradiation to flavins in the presence of thiols and O2 provides Brønsted acidic species that can be used as efficient catalysts for thioacetalizations and for Mannich-type reactions under non-irradiation and mild conditions.

Amide directed hydrocarboxylation of N-allylacetamide catalyzed by the aqueous Pd - tppts - Brønsted acid system (tppts = P(C6H4-m-SO3Na)3)1

2001 ◽  
Vol 79 (5-6) ◽  
pp. 688-692 ◽  
Author(s):  
Göran Verspui ◽  
Gábor Besenyei ◽  
Roger A Sheldon
Keyword(s):  
Substitution Reaction ◽  
Aqueous Media ◽  
Propanoic Acid ◽  
Allylic Substitution ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Mild Conditions ◽  
Brönsted Acid ◽  
Acid Catalyzed ◽  
Hydrolysis Of

The Pd - tppts - HOTs (tppts = P(C6H4-m-SO3Na)3, HOTs = p-toluenesulfonic acid) catalyzed hydrocarboxylation of N-allylacetamide in an aqueous medium afforded 4-acetamidobutyric acid and 3-acetamido-2-methylpropanoic acid under mild conditions, with a high regioselectivity towards the linear isomer. During the hydrocarboxylation an acid catalyzed hydrolysis of the amide moieties of both the substrate and the products took place, as well as the formation of acetamide and propanal, presumably via a Pd-catalyzed allylic substitution reaction of N-allylacetamide. The hydrolysis reaction was suppressed by lowering the amount of Brønsted acid cocatalyst (HOTs) or by employing a weaker Brønsted acid such as propanoic acid. The allylic substitution reaction was minimized by increasing the CO pressure but unfortunately this caused a decrease in the regioselectivity. A sudden inhibition took place after ca. 70% conversion, presumably caused by one of the side products. By increasing the tppts concentration to 13.1 mmol L-1 (20 equiv per Pd) the inhibition was circumvented and a quantitative conversion of N-allylacetamide was achieved.Key words: aqueous media, olefins, palladium, hydrocarboxylation, N-allylacetamide.

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