A simple amine protection strategy for olefin metathesis reactions

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.     

N-(Alkylsulfamoyl)aldimines: easily deprotected precursors for diarylmethylamine synthesis

The sequential reaction of chlorosulfonyl isocyanate with t-BuOH, t-BuNH₂ and TFA allows formation of H₂NSO₂NHBu^t. Condensation of the latter with Ar¹CHO in the presence of Ti(OEt)₄ provides the activated imines Ar¹CHNSO₂NHBu^t (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.     

Density-functional theory for polymer fluids with molecular weight polydispersity

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.     

Catalysis enabled synthesis,structures, and reactivities of fluorinated S8-corona[n]arenes (n = 8–12)

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 S_NAr 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 S_NAr 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 S_NAr functionalisation of the fluoraryl units easily afford diverse libraries of macrocyclic building blocks.     

ChemInform Abstract: First-Principles Study of Defective and Nonstoichiometric Sr2FeMoO6.

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.