2022, Rosenbaum, Lisa-Catherine

2020-06-10, Opel, Julian, Rosenbaum, Lisa-Catherine, Brunner, Julian, Staiger, Anne, Zimmermanns, Ramon, Kellermeier, Matthias, Gaich, Tanja, Cölfen, Helmut, García-Ruiz, Juan-Manuel

Microcarriers with the ability to release and catch substances are highly desired metamaterials and difficult to obtain. Herein, we report a straightforward strategy to synthesize these materials by combining silica-biomorphs with mesocrystals. An easy access to microcarrier hulls with covalently bound spiropyrans as light-switchable anchor points is presented.

2021-02-08, Rosenbaum, Lisa-Catherine, Häfner, Maximilian, Gaich, Tanja

A racemic and scalable enantioselective total synthesis of (+)-waihoensene was accomplished. (+)-Waihoensene belongs to the diterpene natural product family, and it features an angular triquinane substructure motif. Its tetracyclic [6.5.5.5]backbone is all-cis-fused, containing six contiguous stereocenters, four of which are quaternary. These structural features were efficiently installed by means of a diastereoselective radical cyclization, followed by an intramolecular Pauson-Khand reaction, a diastereoselective α-alkylation, and a diastereoselective 1,4-addition reaction. Enantioselectivity was introduced at an early stage, by an asymmetric palladium catalyzed decarboxylative allylation reaction on gram scale.

2020-07-15, Casper, Larissa A., Oßwald, Steffen, Anders, Patrick, Rosenbaum, Lisa-Catherine, Winter, Rainer F.

We have prepared and studied extremely electron‐poor, deeply colored dicationic 1,1'‐bis(diarylmethylium)‐substituted ferrocenes [(η⁵‐C₅H₄‐CAr₂)₂Fe]²⁺ with various aryl substituents as their [B{C₆H₃(CF₃)₂‐3,5}₄]– salts. Due to the strong acceptor substitution, the redox potential for the ferrocene‐based oxidation of the anisyl‐ or 2‐methylanisyl‐substituted congeners 1b²⁺ and 1c²⁺ is close to or even surpasses that of the second oxidation of parent ferrocene, i.e. the Cp₂Fe^+/2+ couple. The strongly Lewis‐acidic character of these complexes is manifest through strong interactions with donor solvents, which lead to a significant reduction of the intensities of the charge‐transfer bands in their electronic spectra and to solvatochromism. The reduced forms of the complexes tend to dimerize or oligomerize as revealed by EPR spectroscopy. Direduced 1b selectively reacts with molecular oxygen to form a peroxo‐bis(diarylmethyl)[4]ferrocenophane, which was also characterized by X‐ray crystallography.