Andreas Orthaber

We report the functionalization and deplanarization of truxenes using pnictaalkene fragments. Selective introduction of one, two, or three Mes*‐ Pn fragments provides up to three fully reversible reductions based on the Pn =C fragments. The incorporation of the unsaturated heteroelement fragment as well as the contortion of the truxene core result in significantly red‐shifted absorption spectra and interesting opto‐electronic properties which are studied by electrochemistry and spectro‐electrochemistry. Incorporation of arsaalkene (As=C) motifs gives significantly milder reduction potentials and red‐shifted absorption, while phosphaalkene decorated truxene P3 can be functionalized using Au(I)Cl coordination. Furthermore, solubility is markedly increased upon incorporation of the Pn ‐Mes* fragments which renders these materials suitable for solution processing.

The first examples of a π‐conjugated benzo[ b ]phosphole P ‐oxide in which two phosphole P ‐oxide units are connected by a carbon‐carbon double bond are described. The molecules are synthesized as E isomers with respect to the carbon‐carbon double bond and exist as stable cis and trans isomers (chiral and meso one respectively) relatively to the two stereogenic P atoms. The optical and electrochemical properties of both isomers have been investigated by experiment and computations.

A catalytic enantioselective β‐O‐elimination reaction is reported in the form of a zirconium‐catalyzed asymmetric opening of meso ‐ketene acetals. Furthermore, a regiodivergent β‐O‐elimination is demonstrated. The reaction proceeds under mild conditions, at low catalyst loadings, and produces chiral monoprotected cis‐ 1,2‐diols in good yield and enantiomeric excess. The combination with a Mitsunobu reaction or a one‐pot hydroboration/Suzuki reaction sequence then gives access to additional diol and aminoalcohol building blocks. A stereochemical analysis supported by DFT calculations reveals that a high selectivity in the hydrozirconation step is also important for achieving high enantioselectivity, although it does not constitute the asymmetric step. This insight is crucial for the future development of related asymmetric β‐elimination reactions.