- Preparation method of articaine hydrochloride intermediate
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The invention relates to a preparation method of an articaine hydrochloride intermediate. The method is characterized by comprising the steps of dissolving 2-methoxycarbonyl-4-methyl-3-oxotetrahydrothiophene into a solvent; then, sequentially adding a catalyst, cyanuric chloride and hydroxylamine hydrochloride; then, carrying out a reaction under the condition of heat preservation; after the reaction is finished, evaporating solvent under reduced pressure, and adding ammonia water into the obtained residue for neutralizing; after that, filtering to obtain a filter cake, washing the filter cakewith water, and then drying to obtain the finished product 3-amino-4-methyl-2-methyl-thiophenecarboxylate. The method has the advantage that the yield of the prepared articaine hydrochloride intermediate, i.e., 3-amino-4-methyl-2-thiophene methyl formate is high and reaches 90% or above.
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Paragraph 0007-0011
(2020/06/16)
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- A rapid conversion of 3-oxothiolanes into 3-aminothiophenes
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3-Oxotetrahydrothiophenes can be rapidly converted into 3-aminothiophenes by refluxing with hydroxylamine hydrochloride in a polar solvent, usually acetonitrile.
- Barker, John M.,Huddleston, Patrick R.,Wood, Michael L.
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p. 2565 - 2568
(2007/10/03)
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- Process for the preparation of thiophene derivatives and also new dihydrothiophene 1-oxides
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Process for the preparation of thiophene derivatives and also new dihydrothiophene 1-oxides. Thiophene derivatives having an--optionally substituted--amino group on the thiophene ring are prepared by dehydrogenating dihydrothiophenes, substituted in a manner identical to that of the desired thiophene derivatives, by means of H2 O2, the dihydrothiophenes being reacted with H2 O2 in a first reaction stage in a neutral medium to give the corresponding sulfoxides, which are then rearranged into the thiophene derivatives by means of acid in the second reaction stage. The dihydrothiophene 1-oxides formed as intermediates in this reaction are new compounds. Like the thiophene derivatives formed from them by rearrangement with acid, they are intermediates, mainly in the sector of plant protection agents and pharmaceuticals.
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- Process for preparing thiophene derivatives
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A process for the preparation of 3-aminothiophenes or acid-addition salts thereof, which comprises reacting the corresponding 3-oxotetrahydrothiophenes with an acid-addition salt of hydroxylamine in the presence of a polar inert solvent and in the absence of a base at a temperature in the range of from 0° to 200° C.
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