Chiroptical studies. Part 101. An empirical analysis of circular dichroism data for steroidal and related transoidαβ-unsaturated ketones

An empirical analysis of c.d. data for steroidal and related transoidαβ-unsaturated ketones substantially confirms existing helicity ‘rules’ for the n→π* and π→π* Cotton effects, and shows that the signs and magnitudes of Δε depend essentially upon the structural class of the bicyclic component containing the chromophore. The third c.d. band, in the region 200–220 nm, has the characteristics expected for the olefinic π_x→π_y* transition, and is relatively insensitive to the immediate environment of the carbonyl group.