New method for preparing 2-amino-5-CBZ-4,5,6,7-tetrahydrothiazolo [5,4-C] pyridine

Abstract

The invention discloses a new method for preparing 2-amino-5-CBZ-4,5,6,7-tetrahydrothiazolo [5,4-C] pyridine. The new method comprises the following steps: performing a mixing and heating reaction onN-tert-butyloxycarbonyl-4-piperidone with sulfur and cyanamide in pyridine, performing cooling, performing filtration, performing washing with an organic solvent, performing drying to obtain pale yellow solid products, performing a mixed low-temperature reaction on the pale yellow solid products and trifluoroacetic acid in dichloromethane, performing concentration, uniformly mixing concentrated substances with triethylamine in dichloromethane, dropwise adding benzyl chloroformate at low temperature, performing a stirring reaction, performing quenching with water, performing extraction with dichloromethane, washing organic phases with water and salt water, performing drying, performing filtration, performing concentration to obtain crude products, and performing pulping with ethyl acetate so as to obtain a final product namely yellow solids. According to the method disclosed by the invention, raw materials low in price are used for replacing original raw materials high in price for preparing end products, the original defects of many by-products during bromination and ring-closing are overcome, the operation is simple, purification is convenient, the cost is reduced, the yield is high, and industrial production and cost control are facilitated.

Description

technical field [0001] The invention relates to the technical field of preparation methods of organic compounds, in particular to a new method for preparing 2-amino-5-CBZ-4,5,6,7-tetrahydrothiazolo[5,4-C]pyridine. Background technique [0002] So far, there are only two reports on the synthesis of the target product by two processes (as follows), [0003] [0004] [0005] The above two types of processes are mainly through the Br 2 Bromination with the starting material, followed by ring closure with thiourea to obtain the target product 2-amino-5-CBZ-4,5,6,7-tetrahydrothiazolo[5,4-C]pyridine. [0006] The existing problems of the original process mainly include the following points: [0007] 1. The high price of raw materials is not conducive to cost control; [0008] 2. The bromination step is not conducive to control, it is easy to produce a variety of by-products of bromine, and it is not conducive to processing; [0009] 3. The acidity of the thiourea ring-cl...

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Problems solved by technology

[0007] 1. The high price of raw materials is not conducive to cost control;

[0008] 2. The bromination step is not conducive to control, it is easy to produce a variety of by-products of bromine, and it is not conducive to processing;

[0009] 3. The acidity of the thiourea ring-closing step is too strong, and the reaction is easy to remove boc, resulting in low yield;

[0010] 4. The polarity of the by-products after ring closure is not much different from that of the product, so they must be purified by passing through columns, recrystallization, etc., which is not conducive to industrial production

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