Circular dichroism of monocyclic and bicyclic lactones. Restricted and rigid model compounds for the ester chromophore

The circular dichroism of some aliphatic amino acid derivatives. A reexamination

“…In addition, our results (Table II) on the amino acids in their zwitterionic forms (at pH 7) confirm previous reports that protonated amino groups9 and carboxylate anions6•6 do not show any Cotton effect in the 230-270µ region.…”

1,4-Dimethyl-2,5-dioxabicyclo[2.2.1]heptane-3,6-dione: optical resolution, absolute configuration and circular dichroism

“…In contrast to the experimental VCD spectra 4 of dilactones (-)-1 and (-)-3, the similarity of their CD spectra (Figure 2), as well as the spectra of (S,S)-4, 12 allowed us to analyse the influence of structural features of their monocyclic dilactone rings upon the magnitude of the Cotton effect. The latter is proportional to the rotatory strength for the CD bands having almost Gaussian shapes (Figure 2).…”

“…2 Thus, we experimentally supported a correlation, which was suggested previously 2,3 for bridging 1,4-dialkyl dilactones, between the sign of the n-π* Cotton effect and the inherent dilactone ring chirality of the boat enantiomeric form of the S-type 11 [B S , (+)-j 1 (O-CO-C-O), (-)-n-π* Cotton effect] or N-type 11 [B N , (-)-j 1 , (+)-n-π* Cotton effect]. The CD spectra 12 of con-formationally flexible (S,S)-lactide 4 {∆e 221 = -5.7 [(MeO) 3 P=O], ∆e 218 = -5.9 [(CF 3 ) 2 CHOH)]} stabilised 12 in the boat conformation (B S ) by equatorial methyl groups are also consistent with this correlation.…”