反应详情

(−)-(R)—N—((R)-2-Hydroxy-1-phenylethyl)-2-methyl-5-phenylpentanamide was prepared from (±)-2-methyl-5-phenylpentanoic acid (20mb(i)/20mc(i)) in the same manner as (S)—N—((R)-2-hydroxy-1-phenylethyl)-2-methyl-5-phenylpentanamide (19mb(i)) described above. Silica gel chromatography provided separation of the title compound from its diastereomer (19mb(i)) to provide the desired product (30.2 g, 33%) as a white solid; TLC Rf 0.33 (solvent system: 50:50 v/v ethyl acetate-heptane); HPLC retention time 13.25 minutes, Gemini 5μ C18 250×4.6 mm, at ultraviolet wavelength of 210 nm, 1 mL/min, 60:40:0.1 methanol-water-acetic acid, purity 99.36% (R), 0.64% (S); [α]Tλ=α/cl, [α]21.9D=−0.066/(0.01573 g/2 mL)(0.5)=−16.78° (c=0.7865, CHCl3).

1. customSilica gel chromatography provided
2. customseparation of the title compound from its diastereomer (19mb(i))