Chiralpak ig column

Optical rotations were measured using an Autopol VI polarimeter. IR spectra were obtained from Perkin-Elmer 577 spectrometers. Ultraviolet absorption spectra were recorded in MeCN (25 μg/mL) on a UV-2401 PC spectrophotometer. ECD spectra were recorded in MeCN (50 μg/mL) on a Chirascan-plus spectrometer (Applied Photophysics Ltd., Surrey, United Kingdom). NMR spectra were measured in DMSO-d₆ on Bruker AV-400 and Bruker AV-600 spectrometers and calibrated by the solvent peak used. Mass spectrometry was performed on a SYNAPT G2-Si HDMS (Waters Corp., Manchester, United Kingdom) with an electrospray ion source (Waters, Milford, MA) connected to a lock-mass apparatus, which performed real-time calibration correction. Column chromatography was performed with CHP20P MCI gel (75–150 μm, Mitsubishi Chemical Corporation, Japan) and Sephadex LH-20 (GE Healthcare Bio-Sciences AB, Sweden). A Waters 2535 Series machine equipped with a X-bridge C₁₈ column (4.6 × 250 mm, 5 μm) was used for HPLC analysis, and a preparative X-bridge Prep C₁₈ OBD column (19 × 250 mm, 5 μm) was used for sample preparation. Enantioseparations were performed by a Waters Acquity UPC² system (Waters, Milford, MA, United States) with a sample manager, binary solvent manager, compensation solvent pump and column manager on a Daicel Chiralpak IG column (5 μm, 250 × 4.6 mm).

Racemic biotin was synthesized according to a previous report^{23 (link)} Optical resolution by high-performance liquid chromatography (HPLC) was conducted using an HPLC system (LC-20AD pump and SPD-20A detector, Shimadzu Co.) equipped with a CHIRALPAK IG column (Daicel Co., 4.6 mm (ID) × 250 mm, 5 mm). Solute elution was performed at a wavelength of 205 nm. Chromatographic conditions: column temperature, 40 °C; eluent, methanol/acetic acid = 100/0.1 (v/v); flow rate, 1.0 mL/min. [α]_D^{26 (link)} = − 86.2° (c = 1.78, 0.1 M aqueous NaOH). [lit.²⁷ D-biotin: [α]_D^{22 (link)} =  + 91° (c = 1.0, 0.1 M aqueous NaOH)].