The stereoselective synthesis of syn-β-fluoroaziridine building blocks via chiral aryl iodide-catalyzed fluorination of allylic amines is reported. The method employs HF-pyridine as a nucleophilic fluoride source together with mCPBA as a stoichiometric oxidant, and affords access to arylethylamine derivatives featuring fluorine-containing stereocenters in high diastereo- and enantioselectivity. Catalyst-controlled diastereoselectivity in the fluorination of chiral allylic amines enabled the preparation of highly enantioenriched 1,3-difluoro-2-amines bearing three contiguous stereocenters. The enantioselective catalytic method was applied successfully to other classes of multifunctional alkene substrates to afford anti-β-fluoropyrrolidines, as well as a variety of 1,2-oxyfluorinated products.

Electronegative substituents arrayed in 1,3-relationships along saturated carbon frameworks can exert strong influence over molecular conformation due to dipole minimization effects. Simple and general methods for incorporation of such functional group relationships could thus provide a valuable tool for modulating molecular shape. Here, we describe a general strategy for the 1,3-oxidation of cyclopropanes using aryl iodide(I–III) catalysis, with emphasis on 1,3-difluorination reactions. These reactions make use of practical, commercially available reagents and can engage a variety of substituted cyclopropane substrates. Analysis of crystal and solution structures of several of the products reveal the consistent effect of 1,3-difluorides in dictating molecular conformation. The generality of the 1,3-oxidation strategy is demonstrated through the catalytic oxidative ring opening of cyclopropanes for the synthesis of 1,3-fluoroacetoxylated products, 1,3-diols, 1,3-amino alcohols, and 1,3-diamines.

We report a strategy for effecting catalytic, enantioselective carbocationic rearrangements through the intermediacy of alkyl iodanes as stereodefined carbocation equivalents. Asymmetric Wagner-Meerwein rearrangements of β-substituted styrenes are catalyzed by the C 2-symmetric aryl iodide 1 to provide access to enantioenriched 1,3-difluorinated molecules possessing interesting and well-defined conformational properties. Hammett and kinetic isotope effect studies, in combination with computational investigations, reveal that two different mechanisms are operative in these rearrangement reactions, with the pathway depending on the identity of the migrating group. In reactions involving alkyl-group migration, intermolecular fluoride attack is product-and enantio-determining. In contrast, reactions in which aryl rearrangement occurs proceed through an enantiodetermining intramolecular 1,2-migration prior to fluorination. The fact that both pathways are promoted by the same chiral aryl iodide catalyst with high enantioselectivity provides a compelling illustration of generality across reaction mechanisms in asymmetric catalysis. File list (4) download file view on ChemRxiv HAS Wagner Meerwein submission vs.pdf (859.05 KiB) download file view on ChemRxiv WM SI final.pdf (13.61 MiB) download file view on ChemRxiv CIF for compound 3e.cif (1.06 MiB) download file view on ChemRxiv CIF for compound 6.cif (674.28 KiB)

Neutral heteroditopic [2]rotaxane ion-pair host systems were synthesised via a Cu(ii) directed passive metal template strategy. Each rotaxane contains discrete, axle-separated interlocked binding sites for a guest anion and a transition metal countercation. The anion binding sites are composed of convergent X-H (X = C, N) hydrogen bond donor groups, or mixed X-H and C-I hydrogen and halogen bond donor groups, whereas an equivalent three-dimensional array of amine, pyridine and carbonyl oxygen donor groups comprise the transition metal binding site. H NMR titrations experiments in CDCl/CDOD or CDCl/CDOD/DO solvent mixtures reveal that the heteroditopic [2]rotaxane host systems are capable of cooperative anion recognition in the presence of a co-bound Zn(ii) cation.