
TY  - JOUR
A1  - Beecham, AF 
A1  - Collins, DJ 
T1  - The circular dichroism of a,b-unsaturated ketones. I. Circular dichroism in the singlet-singlet and singlet-triplet n «p* transitions of steroidal 4-en-3-ones
JF  - Australian Journal of Chemistry
JO  - Aust. J. Chem.
Y1  - 1980
VL  - 33
IS  - 10
SP  - 2189
EP  - 2197
KW  - 
UR  - https://doi.org/10.1071/CH9802189 
N2  - The circular dichroism from 22 steroidal 4-en-3-ones in cyclohexane solution has been recorded through the wavelength range 400-265 nm. It is shown that both the singlet-triplet and the singlet-singlet n &#8594; &#960;* electronic transitions contribute. Through examination of evidence from c.d. and X-ray structure analysis, it is concluded that the conformation of the chromophore and its immediate environment remains constant under the conditions of measurement. In three of the 6&#946;- substituted compounds the normal, highly structured, negative Cotton effect from the singlet-singlet n &#8594; &#960;* transition is modified by positive c.d. with the same vibrational structuring. The origin of the positive contribution is discussed. 
ER  -

