“On water” palladium catalyzed diastereoselective boronic acid addition to structurally diverse cyclopropane nitriles

2020 ◽  
Vol 18 (43) ◽  
pp. 8886-8898
Author(s):  
Dwaipayan Das ◽  
Prasun Mukherjee ◽  
Asish R. Das
Keyword(s):  
Boronic Acid ◽  
Aqueous Media ◽  
Catalytic Amount ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Arylboronic Acids ◽  
Acid Addition ◽  
Brönsted Acid ◽  
Diastereoselective Addition ◽  
Palladium Catalyzed

An efficient palladium catalyzed diastereoselective addition of arylboronic acids to complex spirocyclopropyl dinitriles is developed in the presence of a catalytic amount of DBSA as a Brønsted acid surfactant in aqueous media.

Facile synthesis of chiral indolines through asymmetric hydrogenation of in situ generated indoles

2018 ◽  
Vol 5 (19) ◽  
pp. 2805-2809 ◽  
Author(s):  
Chang-Bin Yu ◽  
Jie Wang ◽  
Yong-Gui Zhou
Keyword(s):  
Asymmetric Hydrogenation ◽  
Hydrogenation Process ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Facile Synthesis ◽  
One Pot ◽  
Brönsted Acid ◽  
Palladium Catalyzed ◽  
Intramolecular Condensation

A concise synthesis of chiral indolines has been developed through intramolecular condensation, deprotection and palladium-catalyzed asymmetric hydrogenation in a one-pot process with up to 96% ee. A strong Brønsted acid played an important role in both the formation of indoles and asymmetric hydrogenation process.

A highly stereo-divergent Mannich-type reaction catalyzed by Brønsted acid in aqueous media

2001 ◽  
Vol 42 (24) ◽  
pp. 4025-4028 ◽  
Author(s):  
Takahiko Akiyama ◽  
Jun Takaya ◽  
Hirotaka Kagoshima
Keyword(s):  
Aqueous Media ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Type Reaction ◽  
Brönsted Acid

Bronsted acid-type biosurfactant for heterocyclization: a green protocol for benzopyran synthesis

RSC Advances ◽  
2015 ◽  
Vol 5 (103) ◽  
pp. 84610-84620 ◽  
Author(s):  
Smita T. Morbale ◽  
Swati D. Jadhav ◽  
Madhukar B. Deshmukh ◽  
Suresh S. Patil
Keyword(s):  
Catalytic Amount ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Green Protocol ◽  
Acid Type ◽  
Brönsted Acid

Synthesis of benzopyran from the various salicylaldehydes and cyclic 1,3-diketones using catalytic amount of lemon extract as a green biosurfactant.

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.

scholarly journals Chiral Brønsted Acids Catalyze Asymmetric Additions to Substrates that Are Already Protonated: Highly Enantioselective Disulfonimide-Catalyzed Hantzsch Ester Reductions of NH–Imine Hydrochloride Salts

Synlett ◽  
2020 ◽  
Vol 31 (17) ◽  
pp. 1707-1712
Author(s):  
Benjamin List ◽  
Vijay N. Wakchaure ◽  
Carla Obradors
Keyword(s):  
Asymmetric Reduction ◽  
Kinetic Studies ◽  
Catalytic Amount ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Iminium Salts ◽  
Catalytic Activation ◽  
Brönsted Acid ◽  
Chiral Brønsted Acids ◽  
Asymmetric Additions

While imines are frequently used substrates in asymmetric Brønsted acid catalysis, their corresponding salts are generally considered unsuitable reaction partners. Such processes are challenging because they require the successful competition of a catalytic amount of a chiral anion with a stoichiometric amount of an achiral one. We now show that enantiopure disulfonimides enable the asymmetric reduction of N–H imine hydrochloride salts using Hantzsch esters as hydrogen source. Our scalable reaction delivers crystalline primary amine salts in great efficiency and enantioselectivity and the discovery suggests potential of this approach in other Brønsted acid catalyzed transformations of achiral iminium salts. Kinetic studies and acidity data suggest a bifunctional catalytic activation mode.

Synthesis of tetrahydroisoquinolines and isochromans via Pictet–Spengler reactions catalyzed by Brønsted acid–surfactant-combined catalyst in aqueous media

Tetrahedron ◽  
2007 ◽  
Vol 63 (19) ◽  
pp. 4039-4047 ◽  
Author(s):  
Akio Saito ◽  
Masaki Takayama ◽  
Aru Yamazaki ◽  
Junko Numaguchi ◽  
Yuji Hanzawa
Keyword(s):  
Aqueous Media ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Brönsted Acid
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