Chiral brønsted acids
WebApr 13, 2024 · Exquisite control of chemo-, enantio- and diastereoselectivities was successfully achieved using a chiral Brønsted acid (CBA) as the catalyst. WebDespite recent advancements in the development of catalytic asymmetric electrophile induced lactonization reactions of olefinic carboxylic acids, the archetypical hydrolactonization has long remained an unsolved and well-recognized challenge. Here, we report the realization of a catalytic asymmetric hydrolactonization using a confined …
Chiral brønsted acids
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WebFeb 26, 2016 · The valuable source of chirality is hydrolytically stable and can only switch between the anionic state (active Lewis acid) and the Brønsted acidic state, thus allowing very low catalyst loadings. Our findings immediately suggest widespread applications of this activation mode to other reactions susceptible to Lewis acid catalysis. WebMay 20, 2024 · This method features a remarkably broad alkene scope, ranging from mono-substituted and gem -/1,2-disubstituted to the challenging tri- and tetra-substituted alkenes, to provide access to a …
WebMar 21, 2016 · Chiral Brønsted acids have found widespread applications as organocatalysts. Weakly acidic species such as diols and (thio)ureas, typically classified as hydrogen bonding catalysts, as well as stronger phosphoric acids, have proven to be highly effective in catalyzing a wide range of asymmetric transformations. WebApr 12, 2024 · Based upon their exceptional reactivity as cooperative Brønsted acid-base catalysts chiral diphosphane Pd-aqua complexes have successfully been utilized in a broad range of asymmetric transformations. Originally discovered by Sodeoka 25 years ago, they readily form reactive chiral Pd enolates upon deprotonation of b-dicarbonyl compounds …
WebApr 12, 2024 · We have developed a chiral phosphoric acid-catalyzed enantioselective Friedel–Crafts alkylation reaction between pyrroles and indolylmethanols. Wide substrate scope was observed, and a chiral all-carbon quaternary center was constructed at the 3 … WebThe combination of chiral Brønsted acids and achiral or chiral transition-metal complexes emerged as a new strategy in asymmetric synthesis. The merged catalytic approach provides practical synthetic protocols that …
WebMay 9, 2024 · Herein, a facile access to axially chiral N-heterocycles enabled by chiral Brønsted acid-catalyzed 5-endo-dig cyclization of ynamides is disclosed, which …
WebVarious chiral bisamidines have been recently developed as chiral Brønsted acid catalysts [15–19] and chiral ligands [20]. To our best knowledge, however, there has been no report of bisamidine-based combined acid catalysis. For our initial studies, our designed cationic Zn(II)-bisamidine catalyst was making homemade noodles with pasta machineWebJan 1, 2009 · Chiral Brønsted acid catalysis is an emerging area of organocatalysis. Since the pioneering studies of the groups of Akiyama and Terada in 2004 on the use of chiral … making homemade mac and cheeseWebMar 23, 2009 · A new chiral phosphoric acid, derived from 3,3'-diphenyl-H8-binol, exhibited superior catalytic activity and enantioselectivity compared to its structural analogues, affording high enantiOSElectivities ranging from 85 to 97% ee with a wide scope of substrates. 257 PDF making homemade ice cream with machineWebMar 4, 2024 · A chiral Brønsted acid-catalyzed atroposelective cyclization of ynamides is disclosed, which represents the first metal-free protocol for the construction of axially chiral compounds from ynamides. making homemade pasta with a kitchenaid mixerWebApr 12, 2024 · We have developed a chiral phosphoric acid-catalyzed enantioselective Friedel–Crafts alkylation reaction between pyrroles and indolylmethanols. Wide substrate scope was observed, and a chiral all-carbon quaternary center was constructed at the 3 position of indoles in high yields with high to excellent enantioselectivities (up to 99% ee). making homemade pasta sauce with tomatoesWebMar 16, 2024 · Chiral phosphoric acids (PAs) are excellent catalysts for the Diels-Alder reaction. For examples, the aza- Diels Alder reaction of Danishefsky's diene with … making homemade onion rings in air fryerWebNov 1, 2024 · Here we show that chiral Brønsted acids enable the catalytic asymmetric dearomatization reactions of naphthol-, phenol- and pyrrole-ynamides by the direct activation of alkynes. This method leads ... making homemade purses and bags