Theoretical study of the conformational arrangement of 3-benzylidene-2,4-pentanedione and its substructures

The quantum chemical PCILO method was employed for calculation of conformational maps of 3-benzylidene-2,4-pentanedione. The analogous conformational maps of simpler substructures were also investigated to enable investigating the respective interactions. Steric interactions of the acetyl group with the phenyl group and of both acetyl groups were found to play a dominant role. One acetyl group is turned by 60° from the s-cis position, the other is in an s-trans conformation when being in the energetically more favourable sterical arrangement. The obtained data were compared with the experimental results.