A solution of N-[3-(2-dimethylaminoethoxy)-4-methoxyphenyl]-2'-methyl-4'-(5-methyl-1,2,4-oxadiazol-3-yl)biphenyl-4-carboxamide (E1, 0.2 g, 0.41 mmole) in 1,2-dichloroethane (5 ml) was treated at room temperature with 1-chloroethyl chloroformate (0.12 ml, 1.12 mmole) followed by diisopropylethylamine (0.15 ml, 0.86 mmole). The mixture was stirred for 2 hours at room temperature. After removal of solvent in vacuo the residue was treated with methanol (8 ml) and heated under reflux for 30 minutes. The reaction mixture was concentrated in vacuo and the residue treated with saturated aqueous potassium carbonate (10 ml) and extracted with dichloromethane (3×10 ml). The combined organic extracts were dried and concentrated in vacuo. Flash column chromatography on silica gel eluting with 5% MeOH/CH2Cl2 gave the title compound as a light pink solid (0.13 g, 68%) mp 97°-99° C.
