General Experimental Procedures Materials All reactions not involving aqueous solutions or reagents were performed under an atmosphere of argon in oven-dried glassware cooled under vacuum unless otherwise stated. For mixtures of solvents, the ratios given refer to the volumes used. All reagents were obtained from commercial suppliers and used without further purification. Flash column chromatography was performed using Merck Kieselgel (230-400 mesh). All chromatography solvents were distilled

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... fore use. NMR spectra were recorded at room temperature on Bruker DPX-400, DRX-500 and DRX-600 spectrometers using the deuterated solvent as internal deuterium lock; 1 H spectra at 400, 500 and 600 MHz respectively, and 13 C spectra at 100, 125 and 150 MHz. Chemical shifts are reported in parts per million (ppm) and internal references were the residual protic solvent: for d 1 -chloroform, δ H = 7.26 ppm and δ C = 77.0 ppm; for d 4 -methanol, δ H = 3.31ppm and δ C = 49.0 ppm; for d 6 -acetone δ H = 2.05 ppm and δ C = 29.84 ppm. Coupling constants (J) are reported in Hz and recorded to the nearest 0.1 Hz. In reporting the spectral data, the following abbreviations were used: br = broad, s = singlet, d = doublet, t = triplet, q = quartet. Spectra were assigned with information gained from DEPT, COSY, HMBC and HMQC experiments. Melting points were obtained on a Reichert hot stage apparatus and are uncorrected. IR spectra were recorded on a Perkin-Elmer Spectrum I FTIR spectrometer. Samples were applied neat. Only selected absorbances (ν max ) are reported. Peaks are reported in wavenumbers (cm -1 ). HRMS were recorded on a Waters Micromass LCT Premier spectrometer and were reported in units of m/z. Microanaysis was performed in the microanalytical laboratories at the Department of Chemistry, University of Cambridge. Optical rotations were measured on a Perkin Elmer 343 Polarimeter.