Yield:85006-31-1 96.5%

Reaction Conditions:

Stage #1:4-methyl-3-oxotetrahydro-2-thiophencarboxylic acid methyl ester with iron(III) chloride;1,3,5-trichloro-2,4,6-triazine;hydroxylamine hydrochloride in N,N-dimethyl-formamide at 70 - 90; for 4 h;
Stage #2: with ammonium hydroxide for 0.5 h;Reagent/catalyst;Temperature;

Steps:

1-5
Example 5 Dissolve 87 g (0.5 mole) of 2-methoxycarbonyl-4-methyl-3-oxotetrahydrothiophene in 435 ml of N,N-dimethylformamide, and add 2.43 g (0.015 mole) Anhydrous ferric chloride and 2.77 g (0.015 mol) of cyanuric chloride, and then48.6 g (0.7 mol) of hydroxylamine hydrochloride were added, and the reaction was kept at 70-90°C for 4 hours. The solvent was evaporated under reduced pressure (-0.9Mpa) to obtainAdd 600 ml of 25percent ammonia water to the obtained residue and stir for half an hour, and then filter to obtain a filter cake. The filter cake is washed with 500 ml of water anddried to obtain 82.5 g of methyl 3-amino-4-methyl-2-thiophenecarboxylate. 98.3percent, the yield is 96.5percent.

References:

CHANGZHOU WOTENG CHEMICAL TECH CO LTD;Changzhou Woteng Chemical Technology Co., Ltd.;LI HONGGONG;Li Honggong;WEI XINGHONG;Wei Xinghong;YUAN ZHIWEI;Yuan Zhiwei CN108299382, 2018, A Location in patent:Paragraph 0007-0011

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