Friedel-Crafts type reaction of ferrocene with beta-ketoesters

Recent advances in the synthesis of ferrocene derivatives via 3d transition metal-catalyzed C-H functionalization

In recent years, transition-metal-catalyzed C-H functionalization has gradually developed into a powerful tool for the synthesis of ferrocenes in an atom- and step-economic fashion. However, despite significant achievements, the vast majority of these C-H functionalizations required precious 4d or 5d transition metal catalysts. The use of inexpensive and sustainable 3d metals in the C-H functionalization of ferrocenes remains challenging, especially the development of asymmetric versions. Herein, we summarize the remarkable recent progress in the synthesis of ferrocenes by 3d transition metal-catalyzed C-H activation until December 2021.

Recent advances in transition metal-catalyzed C–H bond functionalization of ferrocene derivatives

In this Perspective, recent advances in the emerging field of transition metal-catalyzed C–H bond functionalization of ferrocene derivatives are summarized.

Synthesis of a fluorogenic cyclooctyne activated by Cu-free click chemistry

Cyclooctyne-based probes that become fluorescent upon reaction with azides are important targets for real-time imaging of azide-labeled biomolecules. The concise synthesis of a coumarin-conjugated cyclooctyne, coumBARAC, that undergoes a 10-fold enhancement in fluorescence quantum yield upon triazole formation with organic azides is reported. The design principles embodied in coumBARAC establish a platform for generating fluorogenic cyclooctynes suited for biological imaging.

Spatial and temporal control of surfactant systems

This paper reviews some recent progress on approaches leading to spatial and temporal control of surfactant systems. The approaches revolve around the use of redox-active and light-sensitive surfactants. Perspectives are presented on experiments that have realized approaches for active control of interfacial properties of aqueous surfactant systems, reversible control of microstructures and nanostructures formed within bulk solutions, and in situ manipulation of the interactions of surfactants with polymers, DNA and proteins. A particular focus of this review is devoted to studies of amphiphiles that contain the redox-active group ferrocene - reversible control of the oxidation state of ferrocene leads to changes in the charge/hydrophobicity of these amphiphiles, resulting in substantial changes in their self-assembly. Light-sensitive surfactants containing azobenzene, which undergo changes in shape/polarity upon illumination with light, are a second focus of this review. Examples of both redox-active and light-sensitive surfactants that lead to large (>20mN/m) and spatially localized ( approximately mm) changes in surface tensions on a time scale of seconds are presented. Systems that permit reversible transformations of bulk solution nanostructures - such as micelle-to-vesicle transitions or monomer-to-micelle transitions - are also described. The broad potential utility of these emerging classes of amphiphiles are illustrated by the ability to drive changes in functional properties of surfactant systems, such as rheological properties and reversible solubilization of oils, as well as the ability to control interactions of surfactants with biomolecules to modulate their transport into cells.

Fancy bioisosteres: metallocene-derived G-protein-coupled receptor ligands with subnanomolar binding affinity and novel selectivity profiles

Metallocene-derived bioisosteres lead to exceptionally strong binding G-protein-coupled receptor ligands, indicating substantial plasticity of the receptor excluded volume. Novel binding profiles of ferrocenylcarboxamides combining subnanomolar Ki values for the dopamine D4 receptor (1a, 0.52 nM; 1b, 0.63 nM) with superpotent serotonin 5-hydroxytryptamine1A (1a, 0.50 nM) and dopamine D3 receptor binding (1b, 0.64 nM) and selective D4 agonist properties of the ruthenocene 1c may be a starting point for highly beneficial central nervous system active drugs.