Prepstar sd 1

Compound 3 was synthesized as previously reported. Briefly, a solution of the appropriate nitrone (5 mmol) and allyl alcohol (5.8 g, 6.8 mL, 100 mmol), in dimethylformamide (DMF) (100 mL), was heated in a sealed tube for 24 h at 140 °C. The solvent was evaporated at reduced pressure and the residue was first purified by flash chromatography column (Merck Group, Darmstadt, Germany) on silica gel (chloroform/methanol, 9:1) and then by a preparative HPLC (Varian PrepStar SD-1, Varian Inc. Palo Alto, CA, USA) [microsorb silica DYNAMAX-100 Å (21 × 250 mm) column, flow 3.5 mL/min] utilizing a mixed isocratic and linear gradient of 2-propanol (10%, 0–15 min, 10–15%, 15–20 min) in n-hexane. All spectroscopic data correspond to the literature ones. Compounds 3 was crystallized by dissolving it in a flask with ethanol and allowing a very slow and controlled evaporation of the solvent. Plate, clear and almost colorless crystals were then harvested.