Synthesis
A solution of 0.05 M Na2HPO4 (10.0 mL) was added to a 25-mL solution of undiluted commercial household bleach (Clorox). The pH of the resulting buffered solution (0.55 M in NaOCl) was adjusted to pH 11.3 by addition of a few drops of 1 M NaOH solution. This solution was cooled to 0 °C and then added at once to a 0 °C solution of the manganese catalyst (260 mg, 0.4 mmol) and cis-o-methylstyrene (1.18 g, 10 mmol) in 10 mL of CH2Cl2. The two-phase mixture was stirred at room temperature, and the reaction progress was monitored by TLC. After 3 h, 100 mL of hexane was added to the mixture and the brown organic phase was separated, washed twice with 100 mL of H2O and once with 100 mL of saturated NaCl solution, and then dried (Na2SO4). After solvent removal, the residue was purifified by flflash chromatography on silica gel to afford the epoxide (0.912 g, 68%). The ee of the epoxide was determined to be 84% by 1 H NMR analysis in the presence of Eu(hfc)3.
Reference: Zhang, W.; Jacobsen, E. N. J. Org. Chem. 1991, 56, 2296−2298.
