Dissymmetric chromophores. 7. Optical activity of conjugated cisoid dienes: experimental-theoretical study of 5-alkyl-1,3-cyclohexadienes

Lightner, David A.; Bouman, Thomas D.; Gawroński, Jacek; Gawrońska, K.; Chappuis, Jacques L.; Crist, B. Vincent; Hansen, Aage E.

doi:10.1021/ja00408a007

Cited by 42 publications

(30 citation statements)

References 7 publications

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“…Finally, we consider it worth noting that, as reported by Lightner et al in 198l 26 and recently by Hansen and Bak, 27 ab initio calculations of the lowest-energy CEs of chiral 1,3-cyclohexadienes confirm the overriding importance of consignate chirality contributions or perturbations by axial allylic and homoallylic groups or, in their absence, by opposite consignate chirality contributions from the doubly allylic C5-C6 bond or from more distant groups. 26 For the twisted cisoid 1,3-butadiene moiety itself, in which the 1 and 4 positions are not linked by two sp 3 hybridized carbons, as they are in 1,3-cyclohexadienes, these calculations agree with the original diene helicity rule 28 by predicting a positive, though not necessarily very strong, 27 CE for P diene chirality.…”

Section: Resultssupporting

confidence: 76%

“…26 For the twisted cisoid 1,3-butadiene moiety itself, in which the 1 and 4 positions are not linked by two sp 3 hybridized carbons, as they are in 1,3-cyclohexadienes, these calculations agree with the original diene helicity rule 28 by predicting a positive, though not necessarily very strong, 27 CE for P diene chirality. As seen here, structural and substituent effects clearly determine the strength of the lowest-energy CEs of chiral nonhomoannular cisoid conjugated dienes.…”

Section: Resultsmentioning

confidence: 63%

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Diene chirality and cotton effects of nonhomoannular cisoid conjugated dienes: Circular dichroism and crystal structure of a steroidal 19‐nor‐1(10),9(11)‐diene derived from westphalen's diol diacetate

Burgstahler¹,

Jahansouz²,

Véliz³

et al. 2002

Chirality

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Nonhomoannular cisoid conjugated dienes exhibit negative lowest energy pi-->pi* Cotton effects when they have P diene chirality and positive CEs when they have M diene chirality. We investigated this relationship further with a variety of such dienes by MM2 conformational energy-minimization calculations and by an X-ray crystal structure of a steroidal 19 nor 1(10),9(11) diene. CEs are stronger when each double bond of the diene is endocyclic in a different ring and weaker when only one of the double bonds is endocyclic or when neither double bond is endocyclic. They are also stronger when axial allylic and homoallylic substituents with CH/pi interactions are present that exert consignate chirality contributions.

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Section: Resultssupporting

confidence: 76%

Section: Resultsmentioning

confidence: 63%

Diene chirality and cotton effects of nonhomoannular cisoid conjugated dienes: Circular dichroism and crystal structure of a steroidal 19‐nor‐1(10),9(11)‐diene derived from westphalen's diol diacetate

Burgstahler¹,

Jahansouz²,

Véliz³

et al. 2002

Chirality

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“…In the present case, the calculated rotational strengths (R) of the lowest energy diene p-p* transitions generally differ for conformers having P and M helicity ( Table 2). Previous studies have shown that 1,3-cyclohexadiene and 1,2-cis-dihydrodiol conformers contribute rotational strength in accordance with the sign of diene torsion angle g. 26,38 The presence of a bromine (e.g., 4a) or a cyano substituent at C(3) may reverse the relationship.…”

mentioning

confidence: 96%

“…Using the chiroptical data for dihydrodiols listed in Table 4 and elsewhere, 38 we can additionally predict the ACs of other halogenated cis-dihydrodiols 2e-2g, 3e, 3f, and 5a-5f. As in our previous publication, 27 we used the analogy between the properties of Cl, Br, and I, as well as between Me and Et substituted cis-dihydrodiols.…”

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confidence: 99%

Determination of absolute configuration of conformationally flexible cis‐dihydrodiol metabolites: Effect of diene substitution pattern on the circular dichroism spectra and optical rotations

et al. 2007

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Absolute configurations of a number of cis-dihydrodiols (cis-1,2-dihydroxy-3,5-cyclohexadienes), synthetically useful products of TDO-catalyzed dihydroxylations of 1,2- and 1,3-disubstituted benzene derivatives, have been determined by a comparison of calculated and experimental CD spectra and optical rotations and by methods involving X-ray crystallography, 1H NMR spectra of diastereoisomeric derivatives, and by stereochemical correlations. The computations disclosed a significant effect of the substituents on conformational equilibria of cis-dihydrodiols and chiroptical properties of individual conformers. The assigned absolute configurations of cis-dihydrodiols have allowed the validity of a simple predictive model for TDO-catalyzed arene dihydroxylations to be extended.

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“…Our results support the allylic bond polarization (ABP) mode15J1 and show that the diene quadrant rule of Moriarty et a1.12 is not applicable to (-)-a-phellandrene. Lightner et al 13 have performed ab initio RPA computations on 5-alkyl-1,3-cyclohexadienes and applied a different type of analysis to the optical activity of the So -S 2 transition based on localized molecular orbitals. (Idealized geometries incorporating planar double bonds were used in the computation).…”

Section: Resultsmentioning

confidence: 99%

Electronic optical activity of (−)‐α‐phellandrene

1983

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Molecular orbital computations on the sign and magnitude of the Cotton effect of (-)-a-phellandrene (a conjugated diene) and the separate twisted butadiene chromophore were performed using configuration interaction (CI) and the random phase approximation (RPA) methods with a standard minimal basis set of STO/3G orbitals. The relative contributions to the rotatory strength of (-)-a-phellandrene which arise from a twist in the diene unit, the allylic axial bond, and nonplanarity of either one or both of the C=C double bonds were determined by examining various molecular geometries. This theoretical study confirms that the allylic axial substituent/bond provides the largest contribution to the longwavelength Cotton effect. It is found that the rotatory strength arising from distortion of the planar geometry of the double bonds tends to cancel the rotatory strength arising from the sense of twist of the diene unit. The computed energies suggest that molecular geometries where the trisubstituted bond is kept planar, and where twisting is allowed about the cis double bond, may be favored over geometries where torsion is allowed about both double bonds.

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Dissymmetric chromophores. 7. Optical activity of conjugated cisoid dienes: experimental-theoretical study of 5-alkyl-1,3-cyclohexadienes

Cited by 42 publications

References 7 publications

Diene chirality and cotton effects of nonhomoannular cisoid conjugated dienes: Circular dichroism and crystal structure of a steroidal 19‐nor‐1(10),9(11)‐diene derived from westphalen's diol diacetate

Diene chirality and cotton effects of nonhomoannular cisoid conjugated dienes: Circular dichroism and crystal structure of a steroidal 19‐nor‐1(10),9(11)‐diene derived from westphalen's diol diacetate

Determination of absolute configuration of conformationally flexible cis‐dihydrodiol metabolites: Effect of diene substitution pattern on the circular dichroism spectra and optical rotations

Electronic optical activity of (−)‐α‐phellandrene

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