Example 3
General methods: All non-aqueous reactions were performed in oven-dried glassware under an inert atmosphere of dry nitrogen. All the reagents and solvents were purchased from Aldrich (St. Louis, Mo.), Alfa-Aesar (Ward Hill, Mass.), Combi-Blocks (San Diego, Calif.), Ark Pharm (Libertyville, Ill.) and used without further purification. Analytical thin-layer chromatography was performed on Silica Gel GHLF 10×20 cm Analtech TLC Uniplates (Analtech, Newark, Del.) and were visualized by fluorescence quenching under UV light. Biotage SP1 Flash Chromatography Purification System (Charlotte, N.C.) (Biotage SNAP Cartridge, silica, 50 g & 100 g) was used to purify the compounds. 1H NMR and 13C NMR spectra were recorded on a Varian Inova-500 spectrometer (500 MHz) (Agilent Technologies, Santa Clara, Calif.) or a Bruker Ascend 400 (400 MHz) (Billerica, Mass.) spectrometer. Chemical shifts are reported in ppm on the δ scale and referenced to the appropriate solvent peak. Mass spectra were collected on a Brucker ESQUIRE electrospray/ion trap instrument in the positive and negative modes. High resolution mass spectrometer (HRMS) data were acquired on a Waters Xevo G2-S QTOF (Milford, Mass.) system equipped with an Acquity I-class UPLC system.