Diisopropylethylamine → (3RS)-3-{5-[2-(2-o-tolylamino-benzoxazol-6-yl)-acetylamino]-pyrid-2-yl}-butyric acid ethyl ester

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Reaction Steps

A stirred solution of 2-o-tolylamino-benzoxazol-6-acetic acid (0.42 g, Reference Example 2) in dimethylformamide (15 mL) was treated with O-(7-azabenzotriazol-1-yl)-1,1,3,3-tetramethyluronium hexafluorophosphate (0.57 g), then with diisopropylethylamine (0.4 g) and then with a solution of ethyl (3RS)-3-(5-aminopyrid-2-yl)butyrate (0.3 g, Reference Example 5) in dimethylformamide (5 mL). The mixture was stirred at room temperature for 5 hours then left to stand over night and then evaporated to low bulk. The residue was partitioned between water and ethyl acetate. The organic phase was washed with dilute acetic acid, then with water, then with aqueous bicarbonate solution (5%), then with water, then with brine, then dried and then evaporated. The residue was subjected to flash chromatography on silica eluting with ethyl acetate to give the title compound (0.5 g) as a colourless glass. TLC: RF=0.36 (eluting with ethyl acetate). MS: 473 (MH+).

Provenance & Evidence