- Preparation method of chiral ligand(3S, 4S)-2, 5-dioxotetrahydrofuran-3, 4-bis(benzyl carbamate)
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The invention relates to the field of chiral transition metal catalysts, and relates to a preparation method of a chiral ligand(3S, 4S)-2, 5-dioxotetrahydrofuran-3, 4-bis(benzyl carbamate). The methodcomprises the following steps: taking internal compensation 1, 3-dibromosuccinic acid as a raw material; carrying out esterification reaction under the catalysis of acid to generate diester (I); carrying out nucleophilic substitution reaction on the compound (I) and amine to obtain a compound (II); carrying out a removal reaction on the compound (II) under the action of trifluoroacetic acid to obtain amino diester (III); carrying out acylation reaction on the compound (III) and acyl chloride to obtain amide (IV); and hydrolyzing the ester group of the compound (IV) into acid (V) under an alkaline condition, and finally performing intramolecular dehydration on the compound (V) to obtain the chiral transition metal catalyst intermediate. The invention provides a simple and convenient industrial production route for the chiral transition metal catalyst intermediate, the reaction operation is simple, the use of an expensive palladium reagent is avoided, and the cost is lower.
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Paragraph 0042-0044
(2020/06/17)
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- Synthesis of dimethyl acetylenedicarboxylate
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The invention discloses synthesis of dimethyl acetylenedicarboxylate. The synthesis steps comprise: (1) dissolving 2,3-dibromosuccinic acid in methanol, adding concentrated sulfuric acid to the reaction solution in a dropwise manner, continuously stirring, and carrying out a reaction for 2-3 h to obtain 2,3-methyl dibromosuccinate; and (2) dissolving the 2,3-methyl dibromosuccinate obtained in thestep (1) into ethanol, adding an alkali substance, stirring, carrying out a heating reflux reaction, and carrying out post-treatment to obtain dimethyl acetylenedicarboxylate. According to the present invention, the operation is simple, the requirement on the operation technology of the technician is not high, the production cost can be effectively saved, and the dimethyl acetylenedicarboxylate obtained through the method has the high purity and can be directly used for the next reaction.
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Paragraph 0013-0015; 0019; 0023
(2018/10/11)
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