Hydrogen Bonding and Internal or External Lewis or Brønsted Acid Assisted (Thio)urea Catalysts

2019 ◽  
Vol 2020 (9) ◽  
pp. 1057-1068 ◽  
Author(s):  
M. Concepción Gimeno ◽  
Raquel P. Herrera
Keyword(s):  
Hydrogen Bonding ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Brönsted Acid

Brønsted Acid Catalysis: Hydrogen Bonding versus Ion Pairing in Imine Activation

2011 ◽  
Vol 50 (28) ◽  
pp. 6364-6369 ◽  
Author(s):  
Matthias Fleischmann ◽  
Diana Drettwan ◽  
Erli Sugiono ◽  
Magnus Rueping ◽  
Ruth M. Gschwind
Keyword(s):  
Hydrogen Bonding ◽  
Acid Catalysis ◽  
Ion Pairing ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Brönsted Acid ◽  
Bronsted Acid Catalysis

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.

Merging Brønsted Acid and Hydrogen-Bonding Catalysis: Metal-Free Dearomatization of Phenolsvia ipso-Friedel-Crafts Alkylation to Produce Functionalized Spirolactams

2018 ◽  
Vol 360 (4) ◽  
pp. 801-807 ◽  
Author(s):  
Shingo Harada ◽  
Irene Mei-Yi Kwok ◽  
Hiroki Nakayama ◽  
Ayaka Kanda ◽  
Tetsuhiro Nemoto
Keyword(s):  
Hydrogen Bonding ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Metal Free ◽  
Brönsted Acid
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