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

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

“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.

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.

Conversion of Xylose to Furfural Using Lewis and Brønsted Acid Catalysts in Aqueous Media

ACS Catalysis ◽  
2012 ◽  
Vol 2 (9) ◽  
pp. 2022-2028 ◽  
Author(s):  
Vinit Choudhary ◽  
Stanley I. Sandler ◽  
Dionisios G. Vlachos
Keyword(s):  
Aqueous Media ◽  
Acid Catalysts ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Brönsted Acid ◽  
Bronsted Acid Catalysts
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