Diisopropylethylamine → (3RS)-3-{5-[2-(4-methyl-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-(4-methyl-2-o-tolylamino-benzoxazol-6-yl)acetic acid (0.13 g, Reference Example 9) in dimethylformamide (5 mL) was treated with O-(7-azabenzotriazol-1-yl)-1,1,3,3-tetramethyluronium hexafluorophosphate (0.166 g), diisopropylethylamine (0.153 mL) and then with a solution of ethyl (3RS)-3-(4-aminopyrid-2-yl)butyrate (0.091 g, Reference Example 5) in dimethylformamide (5 mL). After stirring for 1 hour and then standing at room temperature over night the reaction mixture was diluted with water and then extracted with t-butyl methyl ether. The extracts were dried over magnesium sulphate and then evaporated to give (3RS)-3-{5-[2-(4-methyl-2-o-tolylamino-benzoxazol-6-yl)acetylamino]pyrid-2-yl}butyric acid ethyl ester as a gum. A solution of this gum in ethanol was treated with aqueous lithium hydroxide solution (1M) and after stirring at room temperature for 1 hour the mixture was partially evaporated. The residue was acidified to pH 6-7 by addition of concentrated hydrochloric acid. This mixture was extracted with ethyl acetate. The extracts were dried over magnesium sulphate and then evaporated to give the title compound (0.012 g) as a cream solid. MS (ES negative): 457(MH−).

Provenance & Evidence