Bifunctional Acid Catalysts for Organic Synthesis

2011 ◽  
pp. 161-183 ◽  
Author(s):  
Pingfan Li ◽  
Hisashi Yamamoto
Keyword(s):  
Organic Synthesis ◽  
Acid Catalysts

Urea-Catalyzed Functionalization of Unactivated C–H Bonds

2020 ◽  
Author(s):  
Alex L. Bagdasarian ◽  
Stasik Popov ◽  
Benjamin Wigman ◽  
Wenjing Wei ◽  
woojin lee ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Organic Synthesis ◽  
High Energy ◽  
Acid Catalysts ◽  
Potential Utility ◽  
New Paradigm ◽  
Lewis Acid Catalysts ◽  
Reaction Conditions ◽  
Highly Active ◽  
Acidic Nature

Herein we report the 3,5bistrifluoromethylphenyl urea-catalyzed functionalization of unactivated C–H bonds. In this system, the urea catalyst mediates the formation of high-energy vinyl carbocations that undergo facile C–H insertion and Friedel–Crafts reactions. We introduce a new paradigm for these privileged scaffolds where the combination of hydrogen bonding motifs and strong bases affords highly active Lewis acid catalysts capable of ionizing strong C–O bonds. Despite the highly Lewis acidic nature of these catalysts that enables triflate abstraction from sp<sup>2</sup> carbons, these newly found reaction conditions allow for the formation of heterocycles and tolerate highly Lewis basic heteroaromatic substrates. This strategy showcases the potential utility of dicoordinated vinyl carbocations in organic synthesis.<br>

Urea-Catalyzed Functionalization of Unactivated C–H Bonds

2020 ◽  
Author(s):  
Alex L. Bagdasarian ◽  
Stasik Popov ◽  
Benjamin Wigman ◽  
Wenjing Wei ◽  
woojin lee ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Organic Synthesis ◽  
High Energy ◽  
Acid Catalysts ◽  
Potential Utility ◽  
New Paradigm ◽  
Lewis Acid Catalysts ◽  
Reaction Conditions ◽  
Highly Active ◽  
Acidic Nature

Herein we report the 3,5bistrifluoromethylphenyl urea-catalyzed functionalization of unactivated C–H bonds. In this system, the urea catalyst mediates the formation of high-energy vinyl carbocations that undergo facile C–H insertion and Friedel–Crafts reactions. We introduce a new paradigm for these privileged scaffolds where the combination of hydrogen bonding motifs and strong bases affords highly active Lewis acid catalysts capable of ionizing strong C–O bonds. Despite the highly Lewis acidic nature of these catalysts that enables triflate abstraction from sp<sup>2</sup> carbons, these newly found reaction conditions allow for the formation of heterocycles and tolerate highly Lewis basic heteroaromatic substrates. This strategy showcases the potential utility of dicoordinated vinyl carbocations in organic synthesis.<br>

Asymmetric C-H and N-H functionalization of Indoles involving Central Chirality via Chiral Phosphoric Acid Catalysis

2021 ◽  
Vol 18 ◽  
Author(s):  
Alemayehu Gashaw ◽  
Dereje Kebebew Debeli ◽  
Meseret Chemeda
Keyword(s):  
Phosphoric Acid ◽  
Organic Compounds ◽  
Organic Synthesis ◽  
Acid Catalysis ◽  
Bond Formation ◽  
Acid Catalysts ◽  
Asymmetric Syntheses ◽  
Chiral Phosphoric Acid ◽  
Great Progress ◽  
Interesting Area

: The C-H and N-H functionalization of indoles is an interesting area of research that has a useful impact on organic synthesis due to the availability of chiral indole scaffolds in the discovery of drugs, synthetic bioactive compounds, and natural products. The chiral phosphoric acid catalysts (CPAs) have proven to be a powerful and versatile class of enantioselective organocatalysts. Many asymmetric syntheses of organic compounds have been carried out with these catalysts in C–C and C-N bond formation reactions, and great progress has been reported. By 2011, several reviews were published covering some important topics and recent achievements in this field. Therefore, in this review, the most recent advances, research breakthroughs with key examples involving mechanisms of CPA-catalyzed C-H and N-H functionalization of indoles to form central chirality via Friedel Crafts, Michael type, and rearrangement reactions were reviewed and reported.

Modified zirconia solid acid catalysts for organic synthesis and transformations

2005 ◽  
Vol 225 (1) ◽  
pp. 71-78 ◽  
Author(s):  
Benjaram M. Reddy ◽  
Pavani M. Sreekanth ◽  
Vangala R. Reddy
Keyword(s):  
Organic Synthesis ◽  
Solid Acid ◽  
Solid Acid Catalysts ◽  
Acid Catalysts

scholarly journals Zeolites Catalyze the Nazarov Reaction and the tert-Butylation of Alcohols by Stabilization of Carboxonium Intermediates

Synthesis ◽  
2020 ◽  
Vol 52 (14) ◽  
pp. 2031-2037
Author(s):  
Antonio Leyva-Pérez ◽  
María Tejeda-Serrano ◽  
Sergio Sanz-Navarro ◽  
Finn Blake
Keyword(s):  
Organic Synthesis ◽  
Butyl Acetate ◽  
Strong Acid ◽  
Organic Reactions ◽  
High Yield ◽  
Acid Catalysts ◽  
Nazarov Cyclization ◽  
Triflic Acid ◽  
Nazarov Reaction ◽  
Tert Butyl

Zeolites are the most used catalysts worldwide in petrochemistry processes, with particular ability to stabilize carbocations. However, the use of zeolites in organic synthesis is still scarce. We show here that representative carboxonium-mediated organic reactions, such as the Nazarov cyclization and the tert-butylation of alcohols with tert-butyl acetate, typically performed with very strong acid catalysts in solution such as triflic acid, can be catalyzed by simple zeolites with high yield and selectivity. The aluminosilicate framework stabilizes the intermediate carboxonium species and overrides the need for superacid protons in solution.

ChemInform Abstract: Bifunctional Acid Catalysts for Organic Synthesis

ChemInform ◽  
2012 ◽  
Vol 43 (7) ◽  
pp. no-no
Author(s):  
Pingfan Li ◽  
Hisashi Yamamoto
Keyword(s):  
Organic Synthesis ◽  
Acid Catalysts

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.

ChemInform Abstract: Novel Supported Solid Acid Catalysts for Environmentally Friendly Organic Synthesis

ChemInform ◽  
2001 ◽  
Vol 32 (16) ◽  
pp. no-no
Author(s):  
Karen Wilson ◽  
J. Kate Shorrock ◽  
Angelique Renson ◽  
Wolfgang Hoyer ◽  
Bertrand Gosselin ◽  
...  
Keyword(s):  
Organic Synthesis ◽  
Solid Acid ◽  
Environmentally Friendly ◽  
Solid Acid Catalysts ◽  
Acid Catalysts

Metal Complexes as Lewis-Acid Catalysts in Organic Synthesis

ChemInform ◽  
2004 ◽  
Vol 35 (22) ◽  
Author(s):  
S. Kobayashi ◽  
Y. Mori ◽  
Y. Yamashita
Keyword(s):  
Metal Complexes ◽  
Organic Synthesis ◽  
Lewis Acid ◽  
Acid Catalysts ◽  
Lewis Acid Catalysts
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