Preservation of the donor-acceptor character of a carbazole-phenalenone dyad upon adsorption on Pt(111).

Donor-acceptor molecules are a subject of great attention due to their immense potential in molecular electronics and photovoltaics. Despite numerous extensive studies demonstrating their functionality in solution, the donor-acceptor character is usually lost upon adsorption on a conducting substrate. Here the concept of breaking the conjugation between the donor and acceptor unit by insertion of a bridge is used.

5-(Hetero)aryl-Substituted 9-Hydroxyphenalenones: Synthesis and Electronic Properties of Multifunctional Donor-Acceptor Conjugates.

5-(Hetero)aryl-substituted 9-hydroxyphenalenones (9-HP) can be readily synthesized by Suzuki coupling of 5-bromo 9-HP with (hetero)aryl boronic acid (derivatives) without protection of the hydroxyl functionality in moderate to excellent yields (57-94 %). A library of 5-(hetero)aryl substituted 9-HP with broad substituent variation was studied with respect to their electronic properties (absorption and emission spectroscopies and cyclic voltammetry) and their computed electronic structures. All compounds show reversible reductive potentials between -1230 and -1110 mV and the donor-substituted representatives possess irreversible oxidation potentials around 600 mV.

Asymmetric Synthesis of Tetracyclic Pyrroloindolines and Constrained Tryptamines by a Switchable Cascade Reaction.

The interrupted Fischer indole synthesis of arylhydrazines and biocatalytically generated chiral bicyclic imines selectively affords either tetracyclic pyrroloindolines or tricyclic tryptamine analogues depending on the reaction conditions. We demonstrate that the reaction is compatible with a variety of functional groups. The products are obtained in high optical purity and in reasonable to good yield.

Masuda borylation-Suzuki coupling (MBSC) sequence of vinylhalides and its application in a one-pot synthesis of 3,4-biarylpyrazoles.

The Masuda borylation-Suzuki coupling (MBSC) sequence was successfully extended to the challenging coupling of vinylhalides with various (hetero)arylhalides using sterically hindered phosphane ligands. Starting from (hetero)arylhalides and α-bromocinnamaldehyde, the sequentially Pd-catalyzed process selectively furnishes α,β-substituted cinnamaldehydes without affecting the reactivity of the Michael system. These intermediates were implemented as entries into a novel synthesis of 3,4-diaryl 1H-pyrazoles in the fashion of a three-step one-pot procedure consisting of a Masuda borylation-Suzuki coupling and subsequent Michael addition-cyclocondensation-elimination sequence.