Propynal → 2-(3-Ethoxycarbonyl-pyridin-2-yl)-piperazine-1,4-dicarboxylic acid di-tert-butyl ester

참여 물질

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To a solution of bis(1,1-Dimethylethyl) 2-[(1Z)-1-amino-3-(ethyloxy)-3-oxo-1-propen-1-yl]-1,4-piperazinedicarboxylate (may be prepared as described in Intermediate 4; 500 mg) in toluene (100 mL), propiolaldehyde (1.0 eq) was added at room temperature. After completion of addition, the reaction mixture was stirred for 2 h at room temperature and then heated to 90° C. Completion of reaction was followed by TLC. TLC showed disappearance of starting material in 5 h. Toluene was removed by vacuo then the residue was diluted with ethyl acetate (100 mL) and washed with water (2×50 mL) followed by brine solution (50 mL) and dried over anhydrous sodium sulphate, concentrated under vacuum to get 600 mg of crude product. The crude product was purified by column chromatography over 100-200 mesh silica gel by using 10%-30% ethyl acetate in pet ether as solvent, which yielded the title compound (200 mg).

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