Characterization of Organic Compounds

Unless otherwise noted, all reagents and solvents were purchased from commercial sources and used without further purification. All reactions were performed under nitrogen atmosphere unless otherwise noted. The NMR spectra were obtained using a 400 or 500 MHz spectrometer. All ¹H NMR spectra are reported in δ units ppm and are referenced to tetramethylsilane (TMS) if conducted in CDCl₃ or to the central line of the quintet at 2.49 ppm for samples in d₆-DMSO. All chemical shift values are also reported with multiplicity, coupling constants and proton count. All ¹³C NMR spectra are reported in δ units ppm and are referenced to the central line of the triplet at 77.23 ppm if conducted in CDCl₃ or to the central line of the septet at 39.5 ppm for samples in d₆-DMSO. Coupling constants (J values) are reported in hertz. Column chromatography was carried out on SILICYCLE SiliaFlash silica gel F60 (40–63 μm, mesh 230–400). High-resolution mass spectra were obtained using a SX-102A mass spectrometer (JEOL USA, Inc., Peabody, MA), a LCT mass spectrometer (Micromass Inc., Beverly, MA) or a Q-tof Ultima API mass spectrometer. All melting points were taken in glass capillary tubes on a Mel-Temp^® apparatus and are uncorrected. All test compounds had a purity ≥ 95% as determined by either elemental analysis or high performance liquid chromatography (HPLC) analysis, unless otherwise noted. The elemental composition of compounds agreed to within ± 0.4% of the calculated values. Chemical and enantiomeric purities were determined using high performance liquid chromatography (HPLC) analysis on a Hewlett-Packard 1100 Series instrument equipped with a quaternary pump and a Daicel Chiralpak AD column (250 × 4.6 mm). UV absorption was monitored at λ = 254 nm. The injection volume was 1 μL. HPLC gradient was 50 % n-hexane and 50 % i-propanol with a flow rate of 1.0 mL/min. In some cases, chemical purity was determined using a Agilent 1100 HPLC instrument equipped with a quaternary pump and a Zorbax® SB-C8 column (30 × 4.6 mm, 3.5 μm). UV absorption was monitored at λ = 254 nm. The injection volume was 5 μL. HPLC gradient went from 5 % acetonitrile and 95 % water to 95 % acetonitrile and 5 % water (both solvents contain 0.1% trifluoroacetic acid) over 1.9 min with a total run time of 2.5 min and a flow rate of 3.0 mL/min.