Chiroptical properties of cyclic α-diketones

摘要: The chiroptical properties of dissymmetric cyclopentanedione, 3-methylcyclopentane-1,2-dione, and glyoxal structures are examined on a theoretical model in which the electronic wave functions obtained from semiempirical all-valence-shell molecular orbital calculations. Excited state constructed virtual orbital-configuration interaction approximation. rotatory strengths, dipole oscillator dissymmetry factors lower energy singletsinglet transitions eleven cyclopentanedione ten calculated reported. signs relative magnitudes strengths associated with two lowest singlet found to be extraordinarily sensitive ring substituents conformational parameters as well inherent chirality within α-dicarbonyl moiety structures. Vicinal effects play significant role determining strengths. For given configurational isomer an inherently group (i.e., P or M), strength transition opposite. This result suggests that cisoid may not useful models for cyclic α-diketone systems dicarbonyl moieties.