1.Optical resolution of (+/-)-all-trans-3-hydroxyretinal by use of high-performance liquid chromatography.
Ito M1, Katsuta Y, Koyama M, Murakami M, Iwaki N, Okano A, Tsukida K. J Nutr Sci Vitaminol (Tokyo). 1992 Apr;38(2):111-5.
Racemic all-trans-3-hydroxyretinal (3-OH-RAL) (1) was converted by a reaction with (-)-camphanic acid chloride (CpCl) into a diastereomixture of camphanates (2a) and (2b) which was separated by preparative high-performance liquid chromatography (HPLC) to give two esters (2a) and (2b) in pure state, respectively. Saponification of (2a) and (2b) independently afforded optically active (3S)- and (3R)-3-OH-RALs (3a) and (3b), respectively, whose absolute structures were determined by circular dichroism (CD) spectra. Racemic 3-OH-RAL was separated to two peaks by HPLC using chiral column (ChiraSpher, Merck). Cochromatography with authentic specimens (3a) and (3b) showed that the peak with a short retention time corresponded to (3R)-isomer and the other to (3S).
2.Novel synthetic approach for optical resolution of cryptophanol-A: a direct access to chiral cryptophanes and their chiroptical properties.
Brotin T1, Barbe R, Darzac M, Dutasta JP. Chemistry. 2003 Dec 5;9(23):5784-92.
The separation by crystallization of the pair of cryptophane diastereomers 1 a and 1 b, obtained in 1:1 ratio by treating racemic anti cryptophanol-A (2) with (-)-camphanic acid chloride, provided a substantial amount of optically pure material (diastereomeric excess>98 %). Subsequent hydrolysis afforded the optically pure cryptophanol-A enantiomers (+)-2 and (-)-2, which were submitted to nucleophilic substitution reactions to provide cryptophane-A (+)-3 and cryptophane monoester (-)-4 in optically pure form. The chiroptical properties of the new cryptophanes 1-4 were investigated by using circular dichroism spectroscopy, and the absolute configuration of the molecules was clearly established. These new cryptophanes represent additional interesting examples for studying the Cotton effect of interacting multichromophoric systems. Moreover, this novel approach presents numerous advantages over the other methods developed so far to obtain optically pure cryptophanes, and compounds (-)-2, (+)-2, and (-)-4 can give access to new enantiopure functionalized cryptophanes with host-guest properties similar to those of cryptophane-A.
3.Camphanic acid chloride: a powerful derivatization reagent for stereoisomeric separation and its DMPK applications.
Licea-Perez H1, Wang S1, Rodgers C1, Bowen CL1, Fang K1, Szapacs M1, Evans CA1. Bioanalysis. 2015 Dec;7(23):3005-17. doi: 10.4155/bio.15.219. Epub 2015 Nov 30.
BACKGROUND: Camphanic acid chloride has proven to be an efficient chiral derivatization reagent for determination of stereoisomers.
4.Vibrational absorption and circular dichroism studies of (-)-camphanic acid.
Buffeteau T1, Cavagnat D, Bouchet A, Brotin T. J Phys Chem A. 2007 Feb 15;111(6):1045-51. Epub 2007 Jan 24.
Vibrational absorption and circular dichroism (VCD) spectra of (-)-(1S,3R)-camphanic acid have been measured in deuterated chloroform solutions at different concentrations (0.005, 0.045, and 0.200 M) in the mid-infrared spectral range. Experimental spectra have been compared with the density functional theory (DFT) absorption and VCD spectra, calculated using the B3PW91 functional and cc-pVTZ basis set for three conformers of both the monomer and the dimer forms of (-)-(1S,3R)-camphanic acid. These calculations indicate that, in the dilute solution, the conformer with intramolecular hydrogen-bonding between the hydroxyl and lactone groups is of lowest energy and represents 70% of the different monomer conformers at room temperature, whereas, in concentrated solution, the dimer formed by intermolecular hydrogen-bonding of carboxyl groups of the two distinct monomer conformations is stabilized. The vibrational absorption and circular dichroism spectra calculated from the Boltzmann population of the individual monomer and dimer conformers are in very good overall agreement with the corresponding experimental spectra, allowing the absolute conformation and configuration of (-)-(1S,3R)-camphanic acid in dilute and concentrated solution, respectively.