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431.
Woodward CP Spiccia ND Jackson WR Robinson AJ 《Chemical communications (Cambridge, England)》2011,47(2):779-781
Acyclic diamines are valuable feedstocks for polyamide synthesis. Ruthenium-alkylidene catalysed cross metathesis of amino alkenes is problematic and acyl derivatisation can result in less efficient syntheses, poor catalyst turnover and isomerisation. Temporary amine masking via stable and soluble ammonium salts delivers cyclic and acyclic aminoalkenes in high yield and purity. 相似文献
432.
The sequential reaction of chlorosulfonyl isocyanate with t-BuOH, t-BuNH2 and TFA allows formation of H2NSO2NHBut. Condensation of the latter with Ar1CHO in the presence of Ti(OEt)4 provides the activated imines Ar1CHNSO2NHBut (59–89%). Commercially available boronic acids add to these imines with good stereoselectivity (76–98% ee) using readily available diene ligands. Simple deprotection with 5% w/w water in pyridine affords free Ar1CHNH2Ar2. 相似文献
433.
We develop a density-functional theory for polydisperse polymer fluids satisfying the Schulz-Flory distribution. The resulting equations are remarkably simple and quickly solved, the computational effort scaling with the polydispersity index, rather than the average molecular weight. Equilibrium, or "living", polymers enter naturally as very polydisperse samples. We illustrate the importance of polydispersity on colloid stability by investigating interactions between adsorbing and nonadsorbing surfaces. Significant free energy barriers are present in monodisperse samples, but these diminish as the degree of polydispersity increases. 相似文献
434.
Andrew. T. Turley Magnus W. D. Hanson-Heine Stephen. P. Argent Yaoyang Hu Thomas. A. Jones Michael Fay Simon Woodward 《Chemical science》2022,14(1):70
Previously inaccessible large S8-corona[n]arene macrocycles (n = 8–12) with alternating aryl and 1,4-C6F4 subunits are easily prepared on up to gram scales, without the need for chromatography (up to 45% yield, 10 different examples) through new high acceleration SNAr substitution protocols (catalytic NR4F in pyridine, R = H, Me, Bu). Macrocycle size and functionality are tunable by precursor and catalyst selection. Equivalent simple NR4F catalysis allows facile late-stage SNAr difunctionalisation of the ring C6F4 units with thiols (8 derivatives, typically 95+% yields) providing two-step access to highly functionalised fluoromacrocycle libraries. Macrocycle host binding supports fluoroaryl catalytic activation through contact ion pair binding of NR4F and solvent inclusion. In the solid-state, solvent inclusion also intimately controls macrocycle conformation and fluorine–fluorine interactions leading to spontaneous self-assembly into infinite columns with honeycomb-like lattices.NR4F salts simultaneously catalyse and template the reaction of dithiols with C6F6 to generate the first fluorinated corona[n]arenes. Simple SNAr functionalisation of the fluoraryl units easily afford diverse libraries of macrocyclic building blocks. 相似文献
435.
The influence of disorder and stoichiometry-breaking point defects on the structural and magnetic properties of Sr2FeMoO6 is studied by electronic structure calculations within the spin-polarized GGA+U approach. 相似文献