Thomas Quell

Solvent-Dependent Facile Synthesis of Diaryl Selenides and Biphenols Employing Selenium Dioxide.

Abstract Biphenols are important structure motifs for ligand systems in organic catalysis and are therefore included in the category of so‐called “privileged ligands”. We have developed a new synthetic pathway to construct these structures by the use of selenium dioxide, a stable, powerful, and commercially available oxidizer. Our new, and easy to perform protocol gives rise to biphenols and diaryl selenides depending on the solvent employed. Oxidative treatment of phenols in acetic acid yields the corresponding biphenols, whereas conversion in pyridine results in the preferred formation of diaryl selenides. As a consequence, we were able to isolate a broad scope of novel diaryl selenides, which could act as pincer‐like ligands with further applications in organic synthesis or as ligands in transition metal catalysis.

Crystal structure of 12-benzyl-sulfanyl-2,9-di-bromo-6H-dibenzo[b,g][1,8]naphthyridin-11-one.

The heterotetracene skeleton of the title molecule, C23H14Br2N2OS, is defined by linear annulation of four six-membered rings, including two N heteroatoms. This moiety is nearly planar (r.m.s. deviation = 0.055 Å), with a slight twist of 4.1 (2)° between the two halves of the aromatic system. The dihedral angle between the least-squares plane of the skeleton and the benzyl group is 24.5 (3)°; the C—S—C angle involving the benzylsulfanyl group is 99.2 (4)°. In the crystal, molecules are π-stacked in an antiparallel fashion along [110], with a distance between the aromatic planes of 3.47 (2) Å. Intermolecular N—H⋯O hydrogen bonds form chains extending parallel to [001] and bridge the antiparallel interdigitated stacks of molecules.