Kott Laila, Petrovic Jelena, Phelps Dean, Roginski Robert, Schubert Jared
Takeda Pharmaceuticals International Co., Analytical Development Small Molecules, 40 Landsdowne St., Cambridge, MA 02139 USA.
Appl Spectrosc. 2014;68(10):1108-15. doi: 10.1366/13-07112. Epub 2014 Oct 1.
The chiral configuration of three of the four chiral centers in the investigational drug MLN4924 is locked by an intermediate (1S,2S,4R)-4-amino-2-(hydroxymethyl)cyclopentanol (designated as INT1a). The intermediate INT1a is a key component to the molecule, but its multiple chiral centers and lack of chromophore make it challenging to analyze for chiral purity of the desired enantiomer when it is contaminated with a small amount of its undesired enantiomer. Vibrational circular dichroism (VCD) is a technique that uses the infrared (IR) regions of the electromagnetic spectrum and as INT1a contains IR active groups, we considered using VCD to determine the chiral purity of INT1a. Since the VCD spectra of enantiomers are of equal intensity and opposite in sign, it was possible to construct calibration curves to detect the presence of low levels of this compound in the presence of its enantiomer. By normalizing the observed intensities of the VCD signals with the observed IR spectra, a partial least squares model was constructed having a root mean squared error of cross validation of 0.46% absolute over a range of 97 to 99.9% pure enantiomer (or 97-99.8% enantiomeric excess). This work demonstrates that VCD can be used for the low-level detection of a compound in the presence of its enantiomer and thus eliminates the need for an ultraviolet chromophore and chromatographic separation of the two enantiomers.
研究药物MLN4924中四个手性中心里有三个的手性构型通过中间体(1S,2S,4R)-4-氨基-2-(羟甲基)环戊醇(命名为INT1a)得以固定。中间体INT1a是该分子的关键组分,但其多个手性中心以及缺乏发色团使得当它被少量不需要的对映体污染时,分析所需对映体的手性纯度具有挑战性。振动圆二色性(VCD)是一种利用电磁光谱红外(IR)区域的技术,由于INT1a含有红外活性基团,我们考虑使用VCD来测定INT1a的手性纯度