Comparison of CD spectra of (2-methylphenyl)- and (2,6-dimethylphenyl)-phenylmethanols leads to erroneous absolute configurations.
Enantiopure (2,6-dimethylphenyl)phenylmethanol (+)-(3) and analog (+)-(4) were prepared and their CD spectra were found opposite to that of (2-methylphenyl)phenylmethanol (R)-(-)-(2), the absolute configuration of which was previously established by X-ray crystallography. Therefore the S absolute configuration was once assigned to (+)-3 and (+)-4. After that we have succeeded in the X-ray analyses of chiral dichlorophthalate esters of (+)-3 and (+)4, which clearly indicated R absolute configuration. It is thus evident that comparison of the CD spectra of alcohols 2, 3, and 4 leads to erroneous absolute configurations.
Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Aoba, Sendai, Japan.
Masashi
M
Kosaka
Shunsuke
S
Kuwahara
Masataka
M
Watanabe
Nobuyuki
N
Harada
Gabriel E
GE
Job
William H
WH
Pirkle