Charge-Transfer Band of 7-Norbornenone. Circular Dichroism of (1R)-2-Deuteriobicyclohept-2-en-7-one and (1R)-2-Methylbicyclohept-2-en-7-one

Article abstract of DOI:10.1021/ja00405a002

(1R)-<2-²H>Bicyclo<2.2.1>hept-2-en-7-one (1), bicyclo<2.2.1>hept-2-en-7-one (7-norbornenone) (2), and (1R)-2-methylbicyclo<2.2.1>hept-2-en-7-one (3) were prepared from (1R)-7,7-dimethoxybicyclo<2.2.1>heptan-2-one p-toluenesulfonylhydrazone of known absolute configuration and optical purity.Circular dichroism spectra of deuterio ketone 1 (Δε₂₇₃^max-0.033, δε₂₂₄^max-0.028, and Δε₂₁₃^max+0.029) and methyl ketone 3 (Δε₂₇₅^max-0.62, Δε₂₂₆^max+2.10, and Δε₂₀₈^max-3.0) confirm the existence of a new low-lying electronic transition near 225 nm whose existence and origin have been questioned during the past 20 years.The partial charge-transfer nature of this band is supported by preliminary calculations in the localized orbital random phase approximation.