Atropisomers of Cofacial Heteroaromatic Rings with Two Positive Charges. Derivatives of 1,8-Di(3‘-pyridyl)naphthalene

Abstract

The two nitrogen atoms in 1,8-di(3'-pyridyl)naphthalene were quaternized by the addition of either benzyl or methyl groups to give dications; the latter was oxidatively converted to the di(6'-pyridone). N-Oxidation gave the mono- and di-N-oxides. All these compounds in DMSO-d(6) show anti-syn atropisomerism at ambient temperatures by (1)H NMR analysis; similar amounts of both diastereomers are present.

Molecular balances for quantifying non-covalent interactions

“…15a-c). [49][50][51][52][53][54] The syn conformation was dominant for all of the compounds depicted in Fig. 15a.…”

“…15a-c). [49][50][51][52][53][54] The syn conformation was dominant for all of the compounds depicted in Figure 15a. The large upfield shielding of the 1 H-NMR methyl signals and the preference for the syn conformation can be attributed to the existence of favourable cation•••arene and CH•••areneinteractions between the positively polarised methyl substituents of one ring and electron-rich naphthalene face of the other.…”

“…Model systems used by Zoltewicz for studying aromatic stacking interactions. [49][50][51][52][53][54] In 2002, Waters examined substituent effects in offset stacking interactions using a related class of rotameric compounds (Figure 16a). 55 Whilst earlier studies had predominantly been performed in organic solvents, the polar nature of these cationic compounds enabled measurements to be obtained in aqueous solution.…”

Synthesis, chiral separation, and absolute configuration of bis‐(N‐aryl) atropisomeric triads: 1,2‐Bis‐[4‐methyl‐2‐(thi)oxo‐2,3‐dihydrothiazol‐3‐yl]‐benzene

“…In the antiform, the two large dipoles of the thiocarbonyl and (or) carbonyl face in opposite directions, the minimization of the dipole-dipole interactions resulting in an anti-form has been already advocated in a triad composed of two pyridine N-oxides attached to a naphthalene. 38,39 The methylmethyl steric interaction in the syn-form might also help to shift the equilibrium toward the sole anti-form. However, such methyl-methyl steric contribution is generally very weak as exemplified in previously reported triads in which both the anti-and syn-isomers were observed with a slight preference for the anti-form.…”

Atropisomeric diastereoisomers from nucleophilic attack on 8-acyl-1-naphthamides

“…1,8-Di-o-tolylnaphthalene can exist as two diastereoisomeric atropisomers: the trans is favoured 3.21 : 1 over the cis at 40 ЊC, and the cis isomer converts to the trans with a barrier of 100.8 kJ mol -1 at this temperature. 13 Barriers to interconversion of naphthalenes bearing meta-substituted phenyl 14, 15 or pyridyl [16][17][18] rings at the 1-and 8-positions are much lower, and these compounds do not exist as atropisomeric diastereoisomers. The conformation 19,20 and racemisation 21 of enantiomeric atropisomers of 8-substituted-1-naphthamides and their thioamide derivatives 22 have been described by Mannschreck and Kiefl, but there are no reported examples of diastereoisomeric non-biaryl atropisomers based on a 1,8disubstituted naphthalene system.…”