Abstract: The present disclosure provides a purification method for 3-amino-5-methylpiperidine with amino protected by Boc. The method includes adding a solvent to the crude product of 3-amino-5-methylpiperidine with amino protected by Boc, heating until it is dissolved to obtain a mixed solution; adding an acid and an amine crystallization auxiliary to the mixed solution, stirring and dispersing to obtain a dispersed solution; cooling the dispersed solution until crystallization, separating and drying same to obtain a salt crystal of 3-amino-5-methylpiperidine with amino protected by Boc. The present disclosure improves the product characters of 3-amino-5-methylpiperidine with amino protected by Boc after salifying and crystallization, thereby improving the yield and purity of the product, at the same time, it simplifies the operation steps of salifying and crystallization of 3-amino-5-methylpiperidine with amino protected by Boc, shortens the operation time, and reduces production costs.

Abstract: Provided in the present disclosure are a nemonoxacin malate active pharmaceutical ingredient with low combination impurities, and a preparation method thereof, specifically, provided in the present disclosure is a method for preparing the nemonoxacin malate active pharmaceutical ingredient, the method includes the following steps: 1) providing a C1-C3 alcohol/water mixed solvent in which nemonoxacin free base (Formula II) and D,L-malic acid are dissolved; and 2) performing cooling crystallization on a mixed solution obtained in the step 1), and then performing solid-liquid separation, washing and drying on a precipitated solid, so as to obtain the nemonoxacin malate active pharmaceutical ingredient.

Abstract: The present disclosure discloses a method for synthesizing quinolones intermediates by a continuous flow reaction. Specifically, according to the method, a microchannel reactor is used, which improves the selectivity and conversion rate of the reaction, and the conversion rate of compound ii is increased to more than 95% and the yield is increased to more than 85%; avoids the use of a solvent such as methanol, and methyl tert-butyl ether, etc., in the intermittent reaction process, which simplifies the post-processing method, shortens the overall operation time from about 24 hours to a few minutes, greatly improving the production efficiency, and realizing the continuity and automation of the whole process; and thus makes the product have high purity and high yield, which is suitable for industrial production.

Abstract: Provided in the present disclosure are a nemonoxacin malate active pharmaceutical ingredient with low combination impurities, and a preparation method thereof, specifically, provided in the present disclosure is a method for preparing the nemonoxacin malate active pharmaceutical ingredient, the method includes the following steps: 1) providing a C1-C3 alcohol/water mixed solvent in which nemonoxacin free base (Formula II) and D,L-malic acid are dissolved; and 2) performing cooling crystallization on a mixed solution obtained in the step 1), and then performing solid-liquid separation, washing and drying on a precipitated solid, so as to obtain the nemonoxacin malate active pharmaceutical ingredient.

Abstract: The present invention provides a crystal form of a thiofuran pyridazine compound, a preparation method therefor and an application thereof. The crystal form of the thiofuran pyridazine compound is (S)-2-(4-fluorophenyl)-4-(piperidine-3-aminomethyl)thieno[2,3-d] pyridazine-7-carboxamide hydrochloride of formula (I). The crystal form of the thiofuran pyridazine compound in the present invention has higher stability and is stored especially in high humidity conditions, and thus is suitable for preparing various forms of drugs.

Abstract: The present invention provides a method for preparing a chiral 4-aryl-?-amino acid derivative. The preparation method comprises hydrogenating an enamine compound having a structure as shown in Formula III in an organic solvent in the presence of a catalyst containing a transition metal and BIBOPs. The preparation method of the present invention uses a small amount of a selected asymmetric catalyst, and has a simple operation, mild reaction conditions, a high yield, a high stereoselectivity, and better industrial application and economic values.

Abstract: The present invention provides a method for preparing an intermediate compound of sitagliptin represented by formula I. The preparation method comprises: dissolving a compound represented by formula II into an organic solvent; and under the catalysis of fatty acid and effect of chlorosilane, performing a reduction reaction of carbon-carbon double bonds, so as to obtain the intermediate compound of sitagliptin represented by formula I, R being methyl or formoxyl. The preparation method of the present invention avoids precious metal as a catalyst, and accordingly, the cost is low, the post-treatment is simple, the product has a high yield, chemical purity and optical purity, and de % is greater than 99.6%, and the preparation method can be used in synthesis of sitagliptin and is suitable for industrial production.

Abstract: The present invention provides a method for preparing an intermediate compound of sitagliptin represented by formula I. The preparation method comprises: dissolving a compound represented by formula II into an organic solvent; and under the catalysis of fatty acid and effect of chlorosilane, performing a reduction reaction of carbon-carbon double bonds, so as to obtain the intermediate compound of sitagliptin represented by formula I, R being methyl or formoxyl. The preparation method of the present invention avoids precious metal as a catalyst, and accordingly, the cost is low, the post-treatment is simple, the product has a high yield, chemical purity and optical purity, and de % is greater than 99.6%, and the preparation method can be used in synthesis of sitagliptin and is suitable for industrial production.