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Circular dichroism and absolute configuration of Aza‐ and Thiaflavanones
Author(s) -
Antus Sándor,
BaitzGács Eszter,
Kajtár Judit,
Snatzke Günther,
Tőkés Adrienne L.
Publication year - 1994
Publication title -
liebigs annalen der chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 0170-2041
DOI - 10.1002/jlac.15619940509
Subject(s) - helicity , circular dichroism , cotton effect , chemistry , chromophore , absolute configuration , enantiomer , spectral line , ring (chemistry) , stereochemistry , flavanone , crystallography , photochemistry , physics , organic chemistry , particle physics , flavonoid , quantum mechanics , antioxidant
The correlation between the absolute configuration and CD of aza‐ and thiaflavanone ( 1, 2 ) is discussed: the 2 R configuration for the laevorotatory enantiomers has been established by a comparison of their CD data with those of ( S )‐(−)‐ 3 . For the Cotton effect within the n → π * band of 1 and 2 the same helicity rule is valid as for the homochirally analogous flavanones ( 3 ). Starting from ( S )‐(−)‐flavanone ( 3 ) and cholesterol ( 5 ), we have synthesized the chromane derivatives 4 and 20 , respectively. The 1 L b band of the chromane chromophore has been unequivocally identified in the range between 255 and 290 nm in the CD spectra of 4 and 20 . For this Cotton effect the opposite helicity rule is valid as compared with the homochirally analogous tetralins: the P/M helicity of the hetero ring leads to a negative/positive CD within the 1 L b band. The modification of the helicity rule can be explained with the help of Petruska's “q values”.