Chiral exploration of 6,12‐diphenyldibenzo[b,f][1,5]diazocine with stable conformation

Abstract

A first optical resolution of 6,12-diphenyldibenzo[b,f][1,5]diazocine with stable boat conformation was achieved by chiral supercritical fluid chromatography (SFC). The absolute configurations of enantiomers were first assigned and determined by X-ray crystal structure based on CIP-rules. The high optical rotation and circular dichroism spectrum were well explained by electronic helix theory. Owing to the high stabilization of boat conformation, the chiral configuration could be maintained at very high temperature, more than 200 °C, which was proved by Density Functional Theory calculations.

Facile Synthesis of Nitrogen-Doped [(6.)m8]nCyclacene Carbon Nanobelts by a One-Pot Self-Condensation Reaction

“…The phenyl or 4- tert -butylphenyl substituents on the eight-membered rings tilt away from the belts, while the 4- n -butylphenyl groups in the optimized geometries of 3 and 4 are almost perpendicular to the anthracene units. The average dihedral angles at the eight-membered rings are 70, 70, 74, and 83°, respectively, which are close to those of most reported structures containing [1,5]­diazocines (about 72–75°), − implying a slightly strained structure in these belts. The benzene, naphthalene, and anthracene units in 1 – 3 are slightly bent outward, while the anthracene moiety in 4 is slightly bent inward.…”

“…In one of our experiments, we obtained 6,12-diphenyldibenzo­[1,5]­diazocine by accident from a refluxed toluene solution of 2-aminobenzophenone and diphenyl phosphate (DPP) with more than 80% yield (Figure b). This one-pot self-condensation cyclization can be dated back to 1896, and it has been achieved under various reaction conditions with excellent yields. − The [1,5]­diazocine can be regarded as a 1,5-nitrogen-doped COT, and its X-ray structure clearly reveals a tub-shaped structure with a bending angle of about 75° (Figure b), which is desirable for the formation of nanobelts containing eight-membered rings. Inspired by this highly efficient self-condensation cyclization reaction and Gleiter’s strategy, we expected that similar reactions starting from precursors carrying bis­( o -aminobenzophenone)­s could give [1,5]­diazocine-containing nanobelts in one pot.…”

“…The benzene, naphthalene, and anthracene units in 1 – 3 are slightly bent outward, while the anthracene moiety in 4 is slightly bent inward. Axial chirality is found in the crystallographic structures of 1 and 2 at a 1:1 racemic ratio (Figure b,e), and the respective R and S isomers pack into 1D channels − by intermolecular [C–H···π] and van der Waals interactions (Figure c,f). The radii of the inner cavities are determined to be 2.32, 3.15, 4.14, and 5.86 Å, respectively (Figure i).…”

Facile Synthesis of a Fully Fused, Three-Dimensional π-Conjugated Archimedean Cage with Magnetically Shielded Cavity

“…One of the orientations was selected for clarity and analysis (Figure e). Axial chirality, induced by the position of nitrogen atoms, is observed in the crystal unit cell with R and S isomers at a 1:1 racemic ratio (Figure f). Short contact analysis suggests the presence of various intermolecular interactions between 1 and o -DCB as a pair of host–guest complex, including π···π (3.573 Å), C–H···π (2.492/2.330/2.211/2.535 Å), and halogen···π (3.307/3.628 Å) interactions (Figure g).…”

“…One of the orientations was selected for clarity and analysis (Figure 2e). Axial chirality, 46 induced by the position of nitrogen atoms, is observed in the crystal unit cell with R and S isomers at a 1:1 racemic ratio (Figure 2f). Short contact analysis suggests the presence of various intermolecular interactions between 1 and 2g).…”