Refernces
10.1002/ejoc.200601101
The study presents an investigation into the scandium-bipyridine-catalyzed enantioselective ring-opening of meso-epoxides using aliphatic alcohols. The research focuses on optimizing the reaction conditions to achieve high yields and enantioselectivities for the production of valuable 1,2-diol monoethers. The study evaluates various metal triflates, solvents, temperatures, ligand architectures, and catalyst loadings to enhance the catalytic efficiency. It was found that scandium-bipyridine complexes, particularly Sc(OTf)3 with bipyridine ligand 2, were the most effective catalysts, providing the best combination of activity and selectivity. The research also explores the scope and limitations of the reaction with different epoxides and alcohols, as well as the potential for catalyst loading reduction without compromising yield or enantioselectivity. A strong positive non-linear effect was observed, indicating aggregation phenomena of the chiral catalyst, which was further supported by structural insights from X-ray crystallography and ESI-MS spectra. The study contributes to the field by providing a method for the enantioselective synthesis of 1,2-diol monoethers from meso-epoxides and aliphatic alcohols.
10.1055/s-2004-822359
The research focuses on the development of a scandium-catalyzed enantioselective allylation method for the synthesis of homoallylic alcohols from aldehydes, using chiral allylboronates derived from camphor. The study explores the optimization of reaction conditions, the scope of substrates, synthetic applications, and mechanistic considerations. Key reactants include scandium triflate as a catalyst, various allyl-, methallyl-, and crotylboronates, and a range of aromatic, aliphatic, and propargylic aldehydes. The experiments utilized techniques such as NMR spectroscopy, HPLC, IR spectroscopy, optical rotation, and elemental analysis to analyze the products and determine their enantiomeric excess, diastereoselectivity, and other properties. The research successfully demonstrated high levels of diastereo- and enantioselectivity in the addition reactions and showcased the methodology's potential through gram-scale synthesis and a concise synthesis of the pheromone (4S)-2-methyloctan-4-ol.
10.1021/jo3011683
The research focuses on the design and synthesis of shape-persistent covalent organic polyhedrons (COPs) through imine condensation/metathesis reactions. The experiments involved the synthesis of a series of dialdehyde compounds and their reaction with complementary triamines to construct COPs. Sc(OTf)3 (Scandium triflate) was used as a catalyst in the imine metathesis reaction. The study explored the structural requirements of the building blocks for successful COP formation, including the distance, angle between reactive sites, and the presence of solubilizing chains. Computer modeling was used to assess the thermodynamic stabilities of the COP structures. Gas adsorption studies were also performed to evaluate the potential of these molecular cages for gas separation, particularly carbon capture. The reactants included various dialdehydes and triamines with different structural and geometrical features, and the analyses used encompassed techniques such as 1H and 13C NMR, GPC, MALDI-MS, and gas adsorption isotherms to characterize and assess the COPs' properties and performance.
10.1016/S0040-4039(00)00257-4
The research investigates the use of amphiphilic calix[6]arene derivatives 1a and 1b as surfactants in Sc(OTf)3-catalyzed Mukaiyama aldol reactions of silyl enol ethers with aldehydes in water. The study finds that these calix[6]arene derivatives can form a hydrophobic microenvironment in the reaction system, which stabilizes labile silyl enol ethers and promotes the reactions. The calix[6]arene derivative 1b, with a hexyl group, performs better than 1a with a butyl group in terms of reaction rates and yields. The results indicate that the alkyl groups on the lower rim of the calix[6]arenes not only stabilize the silyl enol ethers but also promote the aldol reactions in water. The study concludes that calix[6]arene derivatives 1a and 1b are effective surfactants for aqueous Mukaiyama aldol reactions, providing high yields of aldol products.
10.1021/acs.orglett.5b02966
The study presents a novel annulation method for synthesizing electron-deficient imidazo[1,2-a]pyridines and related heterocycles under mild conditions. The process involves treating 2-aminopyridines with a dimethylketal tosylate in acetonitrile at elevated temperatures (80?140 °C) in the presence of catalytic Sc(OTf)3, yielding the desired imidazo[1,2-a]pyridine products in good yields. This method is particularly useful for electron-poor 2-aminopyridines and offers an alternative to the traditional synthesis involving bromoketones with electron-rich and -neutral substrates. The study explores the scope and mechanism of the reaction, discussing the role of various additives and solvents in the cyclization process. The chemicals used in the study include 2-aminopyridines, dimethylketals (specifically tosyl ketal 3), and the catalyst Sc(OTf)3, which serve to facilitate the formation of the imidazo[1,2-a]pyridine ring system through an imine intermediate pathway.
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