Direct Domino Synthesis of Azido-Dienoic Acids: Potential Linker Units
Synlett : Accounts and Rapid Communications in Synthetic Organic Chemistry
S2 General Methods: All glassware was oven dried at 80 ºC before use and all reactions were performed under an atmosphere of argon unless otherwise stated. All solvents were distilled from appropriate drying agents prior to use. All reagents were used as received from commercial suppliers unless otherwise stated. Neat infra-red spectra were recorded using a Perkin-Elmer Spectrum 100 FT-FTIR spectrometer. Wavelengths ( ) are reported in cm -1 . Mass spectra were obtained using a Finnigan MAT
... a Finnigan MAT 8200 or (70 eV) or an Agilent 5973 (70 eV) spectrometer, using electrospray ionization (ESI). Accurate mass determinations were obtained on a Brucker APEX III FT-MS (7 T magnet). All 1 H-NMR and 13 C-NMR experiments were recorded using Bruker DPX-300, AV-400, AV-500 and AV-600 spectrometers at 300 K. Chemical shifts ( ) are quoted in ppm and coupling constants (J) are quoted in Hz. The 7.27 and 2.05 ppm resonance of residual CDCl 3 and CD 3 COCD 2 H for proton spectra and 77.16 and 29.84 ppm resonance of CDCl 3 and CD 3 COCD 3 for carbon spectra were used as internal references. Reaction progress was monitored by thin layer chromatography (TLC) performed on aluminium plates coated with keiselgel F 254 with 0.2 mm thickness. Visualisation was achieved by a combination of ultraviolet light (254 nm) and acidic potassium permanganate or anisaldehyde. Flash column chromatography was performed using silica gel 60 (230-400 mesh, Merck and co.). All the reactions were performed using a stock ethereal solution of bicyclic lactone 1 prepared according to the literature in a concentration typically ranging from 0.15M to 0.25M. No significant change in yields depending on the concentration of 1 was noted in the reactions reported on this study (provided that the concentration is in the range 0.15-0.25M).