Palladium‐Catalyzed Dearomative syn‐1,4‐Carboamination with Grignard Reagents

A protocol for palladium‐catalyzed dearomative functionalization of simple, nonactivated arenes with Grignard reagents has been established. This one‐pot method features a visible‐light‐mediated [4+2] cycloaddition between an arene and an arenophile, and subsequent palladium‐catalyzed allylic substitution of the resulting cycloadduct with a Grignard reagent. A variety of arenes and Grignard reagents can participate in this process, forming carboaminated products with exclusive syn‐1,4‐selectivity. Moreover, the dearomatized products are amenable to further elaborations, providing functionalized alicyclic motifs and pharmacophores. For example, naphthalene was converted into sertraline, one of the most prescribed antidepressants, in only four operations. Finally, this process could also be conducted in an enantioselective fashion, as demonstrated with the desymmetrization of naphthalene.     

Cyclopenta Ring Fused Bisanthene and Its Charged Species with Open‐Shell Singlet Diradical Character and Global Aromaticity/ Anti‐Aromaticity

Cyclopenta ring fused bisanthene and its charged species were synthesized. The neutral compound has an open‐shell singlet ground state and displays global anti‐aromaticity. The dication also exhibits singlet diradical character but has a unique [10]annulene‐within‐[18]annulene global aromatic structure. The dianion is closed‐shell singlet in the ground state and shows global aromaticity with 22 π electrons delocalized on the periphery. These findings prrovide new insight into the design and properties of global aromatic/anti‐aromatic systems based on π‐conjugated polycyclic hydrocarbons.     

Synthesis and Characterization of a Metallacyclic Framework with Three Fused Five‐membered Rings

Polycyclic complexes containing a bridgehead transition metal are interesting species because the transition metal is shared by all the rings simultaneously. In this study, we present a novel osmium–bridgehead system with three fused five‐membered rings. This novel framework can be viewed as a 10‐atom carbon chain coordinating to the osmium center. In sharp contrast to the nonplanar organic analogue, this unique metallacycle exhibits good planarity, which was unambiguously verified by means of X‐ray diffraction. Interestingly, preliminary DFT calculations show that the aromaticity in the three 5MRs of these osmatricycles can be easily tuned by the ligand substitution. Finally, the broad UV/Vis absorption spectra of these novel polycyclic complexes were also reported.