scholarly journals Efficient Synthesis Of Alkyl And Aryl 2,3-Unsaturated Glycopyranosides via Ferrier Rearrangement

2014 ◽  
Vol 7 (2) ◽  
Author(s):  
Dayang Halimatulzahrah Abang Kamal ◽  
Zainab Ngaini
Keyword(s):  
Aromatic Ring ◽  
Lewis Acid ◽  
Lewis Acids ◽  
Aliphatic Alcohol ◽  
Reaction Times ◽  
Acid Catalysts ◽  
Efficient Synthesis ◽  
Lewis Acid Catalysts ◽  
Ferrier Rearrangement

The reactions of 3,4,6-tri-O-acetyl-D-glucal with phenolic and aliphatic alcohol in various Lewis acid catalysts (namely La(NO3)3.6H2O, InCl3, ZnCl2 and BF3•OEt2) have furnished the corresponding alkyl and aryl 2,3-unsaturated glycopyranosides via Ferrier rearrangement. BF3•OEt2 showed the best Lewis acids catalysts with excellent yields and minimum reaction times. The reactions performed in CH3CN gave better yields and shorter reaction times compared to CH2Cl2. The electron withdrawing properties of aromatic ring resulting lower yields of aryl 2,3-unsaturated glycopyranosides compared to alkyl 2,3-unsaturated glycopyranosides under this condition. This study is significant in the preparation of O-glycosides via Ferrier rearrangement.

Bidentate Lewis acid catalysts in asymmetric synthesis

2002 ◽  
Vol 74 (1) ◽  
pp. 123-128 ◽  
Author(s):  
Keiji Maruoka
Keyword(s):  
Asymmetric Synthesis ◽  
Organic Synthesis ◽  
Lewis Acid ◽  
Lewis Acids ◽  
Asymmetric Induction ◽  
Acid Catalysts ◽  
Lewis Acid Catalysts ◽  
High Chemical ◽  
Bidentate Lewis Acids

The chemistry of bidentate Lewis acids belongs to an unexplored field of science, and so far has been only poorly studied. This paper illustrates the design of several bidentate Al and Ti Lewis acids, and their successful application to selective organic synthesis, particularly to asymmetric synthesis. For example, a new, chiral bidentate Ti(IV) complex is successfully designed by adding commercially available Ti(OPri)4 and (S)-binaphthol sequentially to 2,2'-bis(tritylamino)-4,4'-dichlorobenzophenone in CH2Cl2, and can be utilized for simultaneous coordination to aldehyde carbonyls, thereby allowing the precise enantioface discrimination of such carbonyls for a new catalytic, practical enantioselective allylation of aldehydes with allyltributyltin. This chiral bidentate Ti(IV) catalyst exhibits uniformly high asymmetric induction as well as high chemical yields for various aldehydes. The present enantioselective allylation is highly chemoselective in the presence of other carbonyl moieties.

Tropylium salts as efficient organic Lewis acid catalysts for acetalization and transacetalization reactions in batch and flow

2017 ◽  
Vol 19 (17) ◽  
pp. 3993-3996 ◽  
Author(s):  
D. J. M. Lyons ◽  
R. D. Crocker ◽  
D. Enders ◽  
T. V. Nguyen
Keyword(s):  
Lewis Acid ◽  
Lewis Acids ◽  
Acid Catalysts ◽  
Lewis Acid Catalysts ◽  
Tropylium Salts

Tropylium salts were reported as organic-Lewis acids to efficiently catalyze acetalization reactions in batch and flow.

Air- and water-stable Lewis acids: synthesis and reactivity of P-trifluoromethyl electrophilic phosphonium cations

2018 ◽  
Vol 54 (6) ◽  
pp. 662-665 ◽  
Author(s):  
V. Fasano ◽  
J. H. W. LaFortune ◽  
J. M. Bayne ◽  
M. J. Ingleson ◽  
D. W. Stephan
Keyword(s):  
Lewis Acid ◽  
Lewis Acids ◽  
Acid Catalysts ◽  
Bronsted Acid ◽  
Lewis Acid Catalysts ◽  
Reaction Conditions ◽  
Brönsted Acid ◽  
And Function ◽  
Water Alcohol ◽  
Phosphonium Cations

Electrophilic phosphonium cations (EPCs) containing a –CF3 group are stable to air, water, alcohol and strong Brønsted acid and function as Lewis acid catalysts without requiring anhydrous reaction conditions.

Activation of Ethynyl-β-Ionol by Lewis Acid Catalysts: Synthesis of a Novel Branched C20 Molecule

2003 ◽  
Vol 2003 (2) ◽  
pp. 62-62 ◽  
Author(s):  
Frédéric Lamaty
Keyword(s):  
Low Temperature ◽  
Lewis Acid ◽  
Acid Catalysts ◽  
Efficient Synthesis ◽  
Lewis Acid Catalysts

A condensation C15 + C5 between ethynyl-β-ionol and a derivative of prenal was performed at low temperature in the presence of a Lewis acid. The coupling occurs at position 7 of ethynyl-β-ionol and led to the efficient synthesis of a new C20 molecule rather than the expected retinal.

PYRROLE CHEMISTRY: V. FRIEDEL–CRAFTS ISOPROPYLATIONS OF SOME PYRROLE DERIVATIVES

1966 ◽  
Vol 44 (15) ◽  
pp. 1831-1839 ◽  
Author(s):  
Hugh J. Anderson ◽  
L. Cameron Hopkins
Keyword(s):  
Lewis Acid ◽  
Electrophilic Substitution ◽  
Methyl Ketone ◽  
Reaction Times ◽  
Carbonyl Oxygen ◽  
Proton Nuclear Magnetic Resonance ◽  
Acid Catalysts ◽  
Lewis Acid Catalysts ◽  
Pyrrole Derivatives ◽  
Isomer Distribution

The Friedel–Crafts isopropylations of methyl 2-pyrrolecarboxylate, 2-pyrrolecarboxaldehyde, and 2-pyrryl methyl ketone have been investigated under a variety of conditions. Products have been isolated and identified. The effects of different Lewis acid catalysts, solvents, and reaction times upon conversion and product isomer distribution have been determined. These results support the sequence of mechanistic steps suggested in an earlier publication. Further experiments have involved attempted rearrangements and disproportionations under alkylation conditions. The evidence indicates that Lewis acid complexing of the carbonyl oxygen deactivates position 4 in electrophilic substitution less than it does positions 3 and 5. The extent of deactivation of the different positions varies from 2-ester to 2-ketone to 2-aldehyde. Some proton nuclear magnetic resonance investigations of the Lewis acid complexes of these 2-carbonyl pyrroles are also reported.

scholarly journals Defunctionalisation catalysed by boron Lewis acids

2020 ◽  
Vol 11 (47) ◽  
pp. 12604-12615 ◽  
Author(s):  
Huaquan Fang ◽  
Martin Oestreich
Keyword(s):  
Lewis Acid ◽  
Lewis Acids ◽  
Acid Catalysts ◽  
Lewis Acid Catalysts

The combination of boron Lewis acid catalysts and hydride sources enables the cleavage of various carbon–heteroatom bonds.

Establishing the correlation between catalytic performance and N→Sb donor–acceptor interaction: systematic assessment of azastibocine halide derivatives as water tolerant Lewis acids

2019 ◽  
Vol 48 (23) ◽  
pp. 8478-8487 ◽  
Author(s):  
Jian Lei ◽  
Lingteng Peng ◽  
Renhua Qiu ◽  
Yongping Liu ◽  
Yi Chen ◽  
...  
Keyword(s):  
Lewis Acid ◽  
Lewis Acids ◽  
Catalytic Performance ◽  
Acid Catalysts ◽  
Lewis Acid Catalysts ◽  
Acceptor Interaction ◽  
Systematic Assessment ◽  
Donor Acceptor ◽  
Halide Complexes

A series of organoantimony(iii) halide complexes with a tetrahydrodibenzo[c,f][1,5]azastibocine framework were synthesized and employed as water tolerant Lewis acid catalysts.

Metal-free pincer ligand chemistry polycationic phosphonium Lewis acids

2017 ◽  
Vol 46 (12) ◽  
pp. 3921-3928 ◽  
Author(s):  
Kevin M. Szkop ◽  
Douglas W. Stephan
Keyword(s):  
Lewis Acid ◽  
Lewis Acids ◽  
Acid Catalysts ◽  
Phosphonium Salts ◽  
Lewis Acid Catalysts ◽  
Pincer Ligand ◽  
Metal Free ◽  
Methyl Pyridine

Oxidation with or without subsequent methylation of the pyridine of 2,6-bis(diphenylphosphine)methyl pyridine affords di- and tricationic phosphonium salts. These species are used as Lewis acid catalysts for the dimerization of 1,1-diphenylethylene, the hydrodefluorination of 1-fluoroadamantane, and the dehydrocoupling of phenol and silane.

scholarly journals Boron-Based Lewis Acid Catalysis: Challenges and Perspectives

Catalysts ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 5
Author(s):  
Valeria Nori ◽  
Fabio Pesciaioli ◽  
Arianna Sinibaldi ◽  
Giuliana Giorgianni ◽  
Armando Carlone
Keyword(s):  
Organic Synthesis ◽  
Lewis Acid ◽  
Gold Standard ◽  
Lewis Acids ◽  
Acid Catalysis ◽  
Acid Catalysts ◽  
Chemical Transformations ◽  
Lewis Acid Catalysis ◽  
Lewis Acid Catalysts ◽  
Better Than

In the last two decades, boron-based catalysis has been gaining increasing traction in the field of organic synthesis. The use of halogenated triarylboranes as main group Lewis acid catalysts is an attractive strategy. It has been applied in a growing number of transformations over the years, where they may perform comparably or even better than the gold standard catalysts. This review discusses methods of borane synthesis and cutting-edge boron-based Lewis acid catalysis, focusing especially on tris(pentafluorophenyl)-borane [B(C6F5)3], and other halogenated triarylboranes, highlighting how boron Lewis acids employed as catalysts can unlock a plethora of unprecedented chemical transformations or improve the efficiency of existing reactions.

Efficient Synthesis of β-Aminoacrylates and β-Enaminones Catalyzed by Zn(OAc)2·2H2O

2005 ◽  
Vol 70 (11) ◽  
pp. 1943-1952 ◽  
Author(s):  
Ramandeep Kaur Vohra ◽  
Jean-Luc Renaud ◽  
Christian Bruneau
Keyword(s):  
Catalytic Activity ◽  
Lewis Acid ◽  
Primary Amines ◽  
Acid Catalysts ◽  
Efficient Synthesis ◽  
Substituted Anilines ◽  
Lewis Acid Catalysts ◽  
Mild Conditions ◽  
Good Catalytic Activity ◽  
Direct Condensation

The direct condensation of amines with β-ketoesters and β-diketones to produce functional enamine derivatives has been investigated with zinc Lewis acid catalysts. Zn(OAc)2·2H2O shows good catalytic activity and leads to a chemo- and stereoselective formation of (Z)-enamine derivatives from aliphatic primary amines and ring-substituted anilines under mild conditions.

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