Synthesis of a coronene analogue containing an amide bond by Pd-mediated intramolecular C C bond formation of 2-halogenated 4-(alkylamino)benzoic acid cyclic trimer

Synthesis, crystal structure, and properties of methyl-substituted coronene amide analogue

“…The absorption spectrum of 2 without methyl substituents exhibited maxima at 319 and 305 nm and weak maxima at 350 and 379 nm. 21 The absorption spectrum of 3 was similar to that of 2, indicating the similar electronic structure of these compounds. The UV-vis absorption spectra of 3 in tetrahydrofuran and ethyl acetate were similar to that in chloroform, and a notable solvent effect was not observed ( Fig.…”

“… 22 Cyclic triamide 6 was expected to be synthesized from 9 by employing our previous method. 21 To our delight, the introduced three methyl groups do not interfere with these reactions. That is, the reduction of the nitro group of 9 using tin chloride afforded amine 10, and the reductive amination using 10 and isobutyraldehyde afforded N -isobutyl compound 11.…”

“…This result indicated that the rotation of the amide–Ar bond in 6 is suppressed in comparison with that of 4, 26 corresponding to the substrate used in our previously reported palladium reaction without methyl groups. 21 The detailed reaction mechanism for the conversion of anti -6 to 3 is unclear at this point.…”

“…Recently, our group has synthesized 2, a new C 3 symmetrical coronene analogue with three peripheral amide linkages, by the cyclic trimerization of 2-bromo-4-(isobutylamino)benzoic acid, followed by palladium-mediated intramolecular biarylation. 21 The novelty of our procedure is the construction of peripheral bonds of coronene analogue first, followed by the formation of central benzene unit. However, the yield of 2 was low (7%) due to biarylation between the undesired positions.…”