Abstract Herein a palladium/norbornene‐catalyzed sequential ortho ‐acylation and ispo ‐alkenylation for access to polysubstituted aryl ketones has been developed. By exploiting dicyclohexylcarbodiimide (DCC) as activator, aryl with electron‐donating or electron‐withdrawing functionalities, alkyl, and heteroaryl carboxylic acids were compatible in this transformation, affording the desired products in decent to good yields. magnified image
1,3-Dienes derived from (R)-4-t-butyldimethylsilyloxy-2-cyclohexen-1-one react with acyl nitroso dienophiles to form exclusively anti [4+2] cycloaddition products. These regio and diastereoselective acyl nitroso Diels-Alder reactions increase the asymmetric complexity from one chiral center in the starting material to three chiral centers in the products in a single step and provide a powerful approach for the asymmetric synthesis of compounds containing 3,6-dihydro-1,2-oxazine structural feature.
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
A kind of novel uniform monodispersed three-dimensional dendritic mesoporous silica nanospheres (3D-dendritic MSNSs) has been successfully synthesized for the first time. The 3D-dendritic MSNSs can have hierarchical mesostructure with multigenerational, tunable center-radial, and dendritic mesopore channels. The synthesis was carried out in the heterogeneous oil-water biphase stratification reaction system, which allowed the self-assembly of reactants taking place in the oil-water interface for one-pot continuous interfacial growth. The average pore size of each generation for the 3D-dendritic MSNSs can be adjusted from 2.8 to 13 nm independently, which can be controlled by the varied hydrophobic solvents and concentration of silica source in the upper oil phase. The thickness of each generation can be tuned from ∼ 5 to 180 nm as desired, which can be controlled by the reaction time and amount of silica source. The biphase stratification approach can also be used to prepare other core-shell and functional mesoporous materials such as Au nanoparticle@3D-dendritic MSNS and Ag nanocube@3D-dendritic MSNS composites. The 3D-dendritic MSNSs show their unique advantage for protein loading and releasing due to their tunable large pore sizes and smart hierarchical mesostructures. The maximum loading capacity of bovine β-lactoglobulin with 3D-dendritic MSNSs can reach as high as 62.1 wt % due to their large pore volume, and the simulated protein releasing process can be tuned from 24 to 96 h by flexible mesostructures. More importantly, the releasing rates are partly dependent on the hierarchical biodegradation, because the 3D-dendritic MSNSs with larger pore sizes have faster simulated biodegradation rates in simulated body fluid. The most rapid simulated biodegradation can be finished entirely in 24 h, which has been greatly shortened than two weeks for the mesoporous silica reported previously. As the inorganic mesoporous materials, 3D-dendritic MSNSs show excellent biocompatibility, and it would have a hopeful prospect in the clinical applications.
Abstract An alkoxyl radical guided strategy for site‐selective functionalization of unactivated methylene and methine C−H bonds enabled by an Fe II ‐catalyzed redox process is described. The mild, expeditious, and modular protocol allows efficient remote aliphatic fluorination, chlorination, amination, and alkynylation of structurally and electronically varied primary, secondary, and tertiary hydroperoxides with excellent functional‐group tolerance. The application for one‐pot 1,4‐hydroxyl functionalization of non‐oxygenated alkane substrates initiated by aerobic C−H oxygenation is also demonstrated.
Goerge Eliot is a distinguished English female novelist of the 19th century. Living in a period during which conventional ideology still prevailed while modern scientific theories were springing up, her early novels display both modernistic and traditionalistic features. Modernism exists in her keen understanding of human tragedy and the innovative application of psychological realism when depicting the protagonists, while traditionalism is embodied in her nostalgic thematic concern and the traditional way of portraying the minor characters she inherited from the early Victorian novelists. The coexistence of modernism and traditionalism secures a very important position for her early novels in the history of English literature.
The synthesis of indanes bearing substituted cyanomethyl groups at C2 is achieved through Pd-catalyzed coupling reactions between 2-allylphenyl triflate derivatives and alkyl nitriles. Related partially saturated analogues were generated from analogous transformations of alkenyl triflates. The use of a preformed BrettPhosPd(allyl)(Cl) complex as a precatalyst was essential for the success of these reactions.
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
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