Synthesis and Chiroptical Properties of Arylimines of Cholest-4-ene-3,6-dione

In the hope of generating a new class of materials with
large optical
rotations, various arylamines were condensed with cholest-4-ene-3,6-dione
(2) to give 3-arylimino steroids. These compounds possess
moderately high specific rotations ([α]D ∼300–800)
and strong circular dichroism. One such derivative, 3-(4-methoxyphenylimino)­cholest-4-en-6-one
(3), crystallizes as the (E)-imine and
upon dissolution undergoes mutarotation to an equilibrium mixture
of (E)- and (Z)-isomers with a half-life
of approximately 1 h at room temperature, as judged by both NMR spectroscopy
and polarimetry.