Substituent Effects on Selective Syntheses of Fused‐Ring Heterocycles Based on Carbazole and Naphthalene by Photocyclization: Synthesis, Crystal Structures, and Properties

Intramolecular Dehydrogenative Photocyclization of N-Phenyl-1-naphthamides

Here, we explore a dehydrogenative 6π photocyclization method for N-substituted naphthalene carboxamides, which can be conducted in air. This method employs DMSO as both the reaction solvent and oxidant while also stabilizing the excited state of the substrate. Furthermore, the addition of photosensitizer enables the reaction to proceed under a 440-445 nm LED source via energy transfer. The proposed mechanism is initially validated through DFT calculations.

Crystal structure of 8-hexyloxy-2-[(Z)-2-(naphthalen-2-yl)ethenyl]quinoline

In the title mol­ecule, C₂₇H₂₇NO, the naphthalene and quinoline groups are both planar and subtend a dihedral angle of 15.47 (7)°. They are nearly coplanar with the cis-vinyl bridge and the hex­yloxy chain, which adopts an all-trans conformation, resulting in transannular bifurcated intra­molecular C—H⋯N,O contact. The crystal structure features γ-packing of the aromatic moieties, while the parallel packing of alkyl chains resembles that of alkanes.

In the title mol­ecule, C₂₇H₂₇NO, the naphthalene and quinoline groups are both planar and subtend a dihedral angle of 15.47 (7)°. They are nearly coplanar with the cis-vinyl bridge and the hex­yloxy chain, which adopts an all-trans conformation, resulting in transannular bifurcated intra­molecular C—H⋯N,O contact. The crystal structure features γ-packing of the aromatic moieties, while the parallel packing of alkyl chains resembles that of alkanes.

Synthesis, crystal structures and properties of carbazole-based [6]helicenes fused with an azine ring

Novel carbazole-based [6]helicenes fused with an azine ring (pyridine, pyrazine or quinoxaline) have been prepared through a five-step synthetic sequence in good overall yields. Commercially available 2,3-dihaloazines were used as starting materials. To discern the effect of merging an azine moiety within a helical skeleton, the X-ray structures, UV–vis absorption and fluorescence spectra of the helicenes were investigated and compared to that of the parent carbazole-based [6]helicene (7H-phenanthro[3,4-c]carbazole).

Crystal structure of 5,15-dihexyl-5,15-di-hydro-benzo[2,1-b:4,3-c']dicarbazole hexane 0.375-solvate

The title compound, C38H40N2·0.375C6H14, crystallizes in the monoclinic space group P21/c and has a host-guest structure with the helicene molecules forming a porous structure and mol-ecules of hexane inserted into the holes. The dihedral angles between the two carbazole sections of the right- and left-handed helicenes are 27.44 (3) and 25.63 (3)°, respectively. There are no classical π-π inter-actions or hydrogen-bonding inter-actions present between adjacent mol-ecules in the crystal structure. The hexane solvent mol-ecule shows positional disorder.