Yield:21759-69-3 92%

Reaction Conditions:

in methanol;water at 10 - 20;

Steps:

6.1 preparation of methyl (E)-3-(methylamino)but-2-enoic acid ester

In a three-necked flask, methyl 3-oxobutanoate (50 g, 0.8 mol) was dissolved in methanol (100 mL) After cooling to below 10 ° C, the aqueous solution of methylamine (35%, 76 ° C) was slowly added dropwise. After dripping at room temperature overnight. The next day GC-MS The reaction was complete, diluted with ethyl acetate (500 mL), washed with saturated brine (200 mL x 3), partitioned, and the organic phase was used Dried over anhydrous sodium sulfate and concentrated to a white solid which was washed with petroleum ether (200 mL x 2) to give the title compound (51 g, Yield 92%).

References:

CN106316975,2017,A Location in patent:Paragraph 0293-0295