反应详情

A mixture of 5.50 g (25.3 mmol) of ethyl valerate S-methylisothiosemicarbazone (from Step B), 6.55 g (31.5 mmol) of [(2'-cyanobiphenyl-4-yl)methyl]amine (EP 0412594 published Feb. 13, 1991, Merck Case No. 17959IA), and 57 ml of dry EtOH was stirred under N2 at room temperature for 6 days and then concentrated in vacuo at ≤30° C. The residue was chromatographed on a column of silica gel (38×8.8 cm) packed in CH2Cl2. Gradient elution with 0.5-2% MeOH in CH2Cl2 and concentration of combined product fractions gave 6.86 g (71%) of the title compound as a yellow gum; satisfactory purity by TLC in 19:1 CH2Cl2 -MeOH. NMR indicated a mixture of syn and anti isomers.

1. concentrationconcentrated in vacuo at ≤30° C
2. customThe residue was chromatographed on a column of silica gel (38×8.8 cm)
3. washGradient elution with 0.5-2% MeOH in CH2Cl2 and concentration of combined product fractions