Selenium-directed stereoselective [2 + 2] cycloaddition reactions promoted by Lewis acids: a novel zwitterionic intermediate

1992 ◽  
Vol 57 (21) ◽  
pp. 5610-5619 ◽  
Author(s):  
Shoko Yamazaki ◽  
Hiroyuki Fujitsuka ◽  
Shinichi Yamabe ◽  
Hatsue Tamura
Keyword(s):  
Lewis Acids ◽  
Cycloaddition Reactions ◽  
Zwitterionic Intermediate

Efficient Catalytic Effects of Lewis Acids in the 1,3-Dipolar Cycloaddition Reactions of Carbonyl Ylides with Imines

2005 ◽  
Vol 70 (26) ◽  
pp. 10782-10791 ◽  
Author(s):  
Hiroyuki Suga ◽  
Yasutaka Ebiura ◽  
Kazuaki Fukushima ◽  
Akikazu Kakehi ◽  
Toshihide Baba
Keyword(s):  
Lewis Acids ◽  
Dipolar Cycloaddition ◽  
Cycloaddition Reactions ◽  
Catalytic Effects

Gold-catalyzed generation of vinylthionium ions and the development of an organocatalytic, asymmetric (4+3)-cycloaddition reaction

2017 ◽  
Author(s):  
◽  
Michael Topinka
Keyword(s):  
Amino Alcohol ◽  
Good Yield ◽  
Lewis Acids ◽  
Cycloaddition Reaction ◽  
Unsaturated Ester ◽  
Cycloaddition Reactions ◽  
University Of Missouri ◽  
Considerable Problem ◽  
The University ◽  
Substituted Furans

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] An allylic benzoate ester was prepared and used as a progenitor of vinylthionium ions for (4+3)-cycloaddition reactions. The chemistry was limited to 2-substituted and 2,5-disubstituted furans. In the case of 2-substituted furans, only Friedel-Crafts alkylation products were procured. In the case of 2,5-disubstituted furans, (4+3)-cycloaddition products were furnished in good yield. A catalytic, asymmetric variant using 2,5-dialkylfurans and chiral acids to procure cycloaddition products was unsuccessful. There was an opportunity to overcome the Friedel-Crafts alkylation problem that arose in a gold-catalyzed cycloaddition project. A sulfur-substituted unsaturated ester and alcohol were prepared, but silyl migration was a considerable problem upon activation by various agents. The problem of silyl migration was circumvented, but the target aldehyde was unreactive toward dienes in the presence of various Lewis acids. In further pursuit of an asymmetric (4+3)-cycloaddition reaction, 2-substituted furans were reacted with 2-tosyloxycyclopentanone in the presence of K2HPO4/H2O in perfluorobenzene as solvent and 30 mol% of an amino alcohol catalyst developed by David MacMillan. Enantioselectivities were modest for 2-alkylfurans and excellent for 2-arylchalcogenofurans (90% ee). 3-Substituted furans also work in this process.

Nitrones and oxaziridines. XXI. Electronic substituent effects in nitrone cycloadditions to highly polarized alkenes

1978 ◽  
Vol 31 (10) ◽  
pp. 2239 ◽  
Author(s):  
DSC Black ◽  
RF Crozier ◽  
ID Rae
Keyword(s):  
Substituent Effects ◽  
Dipolar Cycloaddition ◽  
Cycloaddition Reactions ◽  
Zwitterionic Intermediate

1,3-Dipolar cycloaddition reactions of nitrones-particularly N-(2'- pyridylmethylene)aniline N-oxide-with arylmethylene cyanoacetates exclusively yield 4,4-disubstituted isoxazolidines, identifiable by 1H n.m.r, spectroscopy and isolable in some cases. Comparative kinetic experiments provide evidence for at least non-synchronous addition via a dipolar intermediate or possibly even two-step addition via a discrete zwitterionic intermediate.

Highly Enantioselective 1,3-Dipolar Cycloaddition Reactions of 2-Benzopyrylium-4-olate Catalyzed by Chiral Lewis Acids

2002 ◽  
Vol 124 (50) ◽  
pp. 14836-14837 ◽  
Author(s):  
Hiroyuki Suga ◽  
Kei Inoue ◽  
Shuichi Inoue ◽  
Akikazu Kakehi
Keyword(s):  
Lewis Acids ◽  
Dipolar Cycloaddition ◽  
Cycloaddition Reactions

scholarly journals Reversal of reaction type selectivity by Lewis acid coordination: the ortho photocycloaddition of 1- and 2-naphthaldehyde

2019 ◽  
Vol 10 (37) ◽  
pp. 8566-8570 ◽  
Author(s):  
Simone Stegbauer ◽  
Noah Jeremias ◽  
Christian Jandl ◽  
Thorsten Bach
Keyword(s):  
Visible Light ◽  
Lewis Acid ◽  
Visible Light Irradiation ◽  
Lewis Acids ◽  
Light Irradiation ◽  
Cycloaddition Reactions ◽  
Reaction Type ◽  
Photochemical Behaviour

Lewis acids, such as AlBr3, completely alter the photochemical behaviour of naphthaldehydes. Instead of typical carbonyl photochemistry, the aldehydes undergo cycloaddition reactions at the arene core upon visible-light irradiation.

Preparation of MOF catalysts and simultaneously modulated metal nodes and ligands via a one-pot method for optimizing cycloaddition reactions

2020 ◽  
Vol 44 (23) ◽  
pp. 9611-9615
Author(s):  
Peng Wang ◽  
Sha Wang ◽  
Wenlei Zhang ◽  
Xiaohan Li ◽  
Zhida Gu ◽  
...  
Keyword(s):  
Lewis Acids ◽  
Cycloaddition Reactions ◽  
Bronsted Acids ◽  
One Pot

MOFs were adjusted with metal nodes and ligands to endow them with Lewis acids and Brønsted acids for enhanced cycloaddition reactions.

In the searching for zwitterionic intermediates on reaction paths of [3 + 2] cycloaddition reactions between 2,2,4,4-tetramethyl-3-thiocyclobutanone S-methylide and polymerizable olefins

RSC Advances ◽  
2015 ◽  
Vol 5 (122) ◽  
pp. 101045-101048 ◽  
Author(s):  
Radomir Jasiński
Keyword(s):  
Dft Calculations ◽  
Cycloaddition Reactions ◽  
Reaction Paths ◽  
Zwitterionic Intermediate ◽  
Step Mechanism

DFT calculations show that the [3 + 2]-cycloaddition of 2,2,4,4-tetramethyl-3-thiocyclobutanone S-methylide with nitroethene takes place according to a polar, two-step mechanism with a zwitterionic intermediate.

Influence of Lewis Acids on the Cycloaddition Reactions of Cyano- and Carbomethoxy-Substituted Olefins

1994 ◽  
Vol 59 (18) ◽  
pp. 5424-5435 ◽  
Author(s):  
Warunee Srisiri ◽  
Anne Buyle Padias ◽  
H. K. Hall
Keyword(s):  
Lewis Acids ◽  
Cycloaddition Reactions
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