Stereostructure and thermodynamic stability of atropisomers of ortho-substituted 2,2′-diaryl-1,1′-binaphthalenes

A series of ortho-substituted 2,2′-aryl-1,1′-binaphthalenes were prepared via Negishi arylation of 2,2′-diiodo-1,1′-binaphthalene in good to high yields (65–95%) as an equilibrium mixtures of up to three atropisomers (unlike,unlike, like,unlike, and like,like). Thermodynamic stability parameters of the atropisomers were evaluated from VT NMR spectra by regression analysis. The DFT parameters calculated using CAM-B3LYP functional comprising solvent permittivity were, apart from the toluene solution, which was expected to interact with the aromatic solute, in qualitative agreement with the experimental values. In the case of the ditolyl derivative, the population of the atropisomers was confirmed by CD spectroscopy via comparison with the population-weighted averaged spectrum computed using the M06 functional. X-ray structure analyses of particular atropisomers of the dianisyl, dianilinyl, and dinaphthyl derivatives are also presented and discussed.

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(R)-2,2’-Bis(2-methoxyphenyl)-1,1’-binaphthaleneC34H26O2[α]D20=+139.9 (c 0.51, CH2Cl2)Source of chirality: (R)-2,2′-diiodo-1,1′-binaphthaleneAbsolute configuration: (R)

(R)-2,2’-Bis[2-(dimethylamino)phenyl]-1,1’-binaphthaleneC36H32N2[α]D20=+66.7 (c 0.53, CH2Cl2)Source of chirality: (R)-2,2′-diiodo-1,1′-binaphthaleneAbsolute configuration: (R)

(S)-2,2′-Bis(2-methylphenyl)-1,1′-binaphthaleneC34H26[α]D20=-76.5 (c 0.50, CH2Cl2)Source of chirality: (S)-2,2′-diiodo-1,1′-binaphthaleneAbsolute configuration: (S)

(R)-2,2’-Bis(2-isopropylphenyl)-1,1’-binaphthaleneC38H34[α]D20=+74.6 (c 0.93, CH2Cl2)Source of chirality: (R)-2,2′-diiodo-1,1′-binaphthaleneAbsolute configuration: (R)

(R,S,S)-1,2’:1’,1″:2″,1″′-QuaternaphthaleneC40H26[α]D20=+888.3 (c 1.05, CH2Cl2)Source of chirality: (R)-2,2′-diiodo-1,1′-binaphthaleneAbsolute configuration: (R,S,S)