(S)-3-[1-(4-Methoxybenzenesulfonyl)-(4S,5S)-4,5-diphenyl-4,5-dihydro-1H-imidazol-2-yl]-1,1'-binaphthalene-2,2'-diyl Hydrogen Phosphate

Experimental procedure: The mixture of 1 (3.1 mg, 0.0042 mmol) and Ca(OMe)₂ (0.4 mg, 0.0042 mmol) in methanol (0.08 mL) is stirred for 1 h. After removal of the solvent under reduced pressure, N-(2-pyridinesulfonyl)cyclohexaneaziridine (20.0 mg, 0.084 mmol) in toluene (1.68 mL) and molecular sieves 4Å (8.4 mg) are successively added, and the whole mixture is stirred at -20 °C. Then, trimethylsilylisothiocyanate (14.2 µL, 0.101 mmol) is added. After the disappearance of aziridine in the reaction mixture monitored by TLC, the water (3.0 mL) is added. The aqueous layer is extracted with CH₂Cl₂, the combined organic layer is dried over Na₂SO₄. Removal of solvent under reduced pressure gives the crude product, which is purified by flash chromatography on silica gel (hexane : ethyl acetate = 50 : 50) to afford the corresponding product as a white solid (24.8 mg, 88% ee) in 99% yield.