title: Circular dichroism of 9,10-dihydrophenanthrene derivatives reveals both the absolute configuration and conformation: a novel approach to Mislow's helicity rule.
abstract: The absolute configuration and the conformation of 9,10-trans-disubstituted 9,10-dihydrophenanthrenes, known chiral metabolites of phenanthrene-9,10-oxide, have been determined by circular dichroism. The absolute configuration assignment is based on the sign of the long-wavelength Cotton effect (A-band), which is conformation invariant and originates from benzylic chirality. This provides a new interpretation of the Mislow biphenyl-helicity rule for the case of the 9,10-dihydrophenanthrene chromophore. The sign of the B-band Cotton effect reflects the conformation of the biphenyl chromophore in 9,10-dihydrophenanthrenes. It is shown that the origin of chiroptical properties of 9,10-dihydrophenanthrenes is closely related to those of 5,6-trans-disubstituted 1,3-cyclohexadienes.
authors.affiliation: Department of Chemistry, A. Mickiewicz University Grunwaldzka, 6 60780 Poznań, Poland. gawronski@amu.edu.pl
authors.forename: Jacek
authors.initials: J
authors.lastname: Gawroński
authors.forename: Piotr
authors.initials: P
authors.lastname: Grycz
authors.forename: Marcin
authors.initials: M
authors.lastname: Kwit
authors.forename: Urszula
authors.initials: U
authors.lastname: Rychlewska