Resolution and Determination of the Absolute Configuration of a Twisted Bis-Lactam Analogue of Tröger's Base: A Comparative Spectroscopic and Computational Study.
(2015) In Journal of Organic Chemistry 80(16). p.8142-8149- Abstract
- The first reported twisted bis-lactam, a racemic Tröger's base (TB) analogue (2), was resolved into its enantiomers on a chiral stationary phase HPLC column. The absolute configuration of (+)-2 was determined to be (R,R)-2 by comparing experimental and calculated vibrational circular dichroism (VCD) and electronic circular dichroism (ECD) spectra. The absolute configuration of (-)-2 was determined by comparing experimental and calculated electronic circular dichroism (ECD) spectra. The corresponding theoretical spectra were calculated using the lowest energy conformation of (R,R)-2 and (S,S)-2 at the B3LYP/6-31G(d,p) level of theory. The absolute configuration of (+)-2 was also determined to (R,R)-2 by anomalous X-ray diffraction (AXRD) in... (More)
- The first reported twisted bis-lactam, a racemic Tröger's base (TB) analogue (2), was resolved into its enantiomers on a chiral stationary phase HPLC column. The absolute configuration of (+)-2 was determined to be (R,R)-2 by comparing experimental and calculated vibrational circular dichroism (VCD) and electronic circular dichroism (ECD) spectra. The absolute configuration of (-)-2 was determined by comparing experimental and calculated electronic circular dichroism (ECD) spectra. The corresponding theoretical spectra were calculated using the lowest energy conformation of (R,R)-2 and (S,S)-2 at the B3LYP/6-31G(d,p) level of theory. The absolute configuration of (+)-2 was also determined to (R,R)-2 by anomalous X-ray diffraction (AXRD) in a chiral space group P212121 using Cu-irradiation resulting in a very low Flack parameter of -0.06(3), despite the heaviest element being an oxygen atom, thus unambiguously confirming the results from the spectroscopic studies. We conclude that, for the Tröger's base (TB) analogue (2), we may rank the reliability of the individual methods for AC determination as AXRD ≫ VCD > ECD, while the synergy of all three methods provides very strong confidence in the assigned ACs of (+)-(R,R)-2 and (-)-(S,S)-2. (Less)
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- author
- organization
- publishing date
- 2015
- type
- Contribution to journal
- publication status
- published
- subject
- in
- Journal of Organic Chemistry
- volume
- 80
- issue
- 16
- pages
- 8142 - 8149
- publisher
- The American Chemical Society (ACS)
- external identifiers
-
- pmid:26244379
- wos:000360103000032
- scopus:84939783025
- pmid:26244379
- ISSN
- 1520-6904
- DOI
- 10.1021/acs.joc.5b01236
- language
- English
- LU publication?
- yes
- id
- c2b83bbb-b72d-4ad5-bc6c-5267d573664c (old id 7844660)
- date added to LUP
- 2016-04-01 10:36:15
- date last changed
- 2022-04-04 19:37:28
@article{c2b83bbb-b72d-4ad5-bc6c-5267d573664c, abstract = {{The first reported twisted bis-lactam, a racemic Tröger's base (TB) analogue (2), was resolved into its enantiomers on a chiral stationary phase HPLC column. The absolute configuration of (+)-2 was determined to be (R,R)-2 by comparing experimental and calculated vibrational circular dichroism (VCD) and electronic circular dichroism (ECD) spectra. The absolute configuration of (-)-2 was determined by comparing experimental and calculated electronic circular dichroism (ECD) spectra. The corresponding theoretical spectra were calculated using the lowest energy conformation of (R,R)-2 and (S,S)-2 at the B3LYP/6-31G(d,p) level of theory. The absolute configuration of (+)-2 was also determined to (R,R)-2 by anomalous X-ray diffraction (AXRD) in a chiral space group P212121 using Cu-irradiation resulting in a very low Flack parameter of -0.06(3), despite the heaviest element being an oxygen atom, thus unambiguously confirming the results from the spectroscopic studies. We conclude that, for the Tröger's base (TB) analogue (2), we may rank the reliability of the individual methods for AC determination as AXRD ≫ VCD > ECD, while the synergy of all three methods provides very strong confidence in the assigned ACs of (+)-(R,R)-2 and (-)-(S,S)-2.}}, author = {{Runarsson, Ögmundur and Benkhäuser, Christian and Christensen, Niels Johan and Artacho Ruiz, Josep and Ascic, Erhad and Harmata, Michael and Snieckus, Victor and Rissanen, Kari and Fristrup, Peter and Lützen, Arne and Wärnmark, Kenneth}}, issn = {{1520-6904}}, language = {{eng}}, number = {{16}}, pages = {{8142--8149}}, publisher = {{The American Chemical Society (ACS)}}, series = {{Journal of Organic Chemistry}}, title = {{Resolution and Determination of the Absolute Configuration of a Twisted Bis-Lactam Analogue of Tröger's Base: A Comparative Spectroscopic and Computational Study.}}, url = {{http://dx.doi.org/10.1021/acs.joc.5b01236}}, doi = {{10.1021/acs.joc.5b01236}}, volume = {{80}}, year = {{2015}}, }