Method for preparing 4-acetoxy-2-azetidinone

Abstract

The invention relates to a method for preparing 4-acetoxy-2-azetidinone, which comprises the following preparation technique steps: a) cyclization reaction; b) hydrolysis reaction; c) filtration; d) extraction; e) concentration; and f) refining. In the invention, the 'one-pot' method and the milder reaction condition are adopted, the technique and equipment are simpler, the improved after-treatment can be more reasonable and more effective, and the whole technique is very easy for realizing industrial production. Finally, the product is refined by adopting the solvent crystallization method, so that the product quality is better, the yield is higher, and the technique is simple, wherein the overall yield of the product is 65-70%, which is 40-50% higher than the yield in the document.

Description

technical field [0001] The invention relates to the field of chemical industry and chemical medicine preparation method. In particular it relates to a process for the production of 4-acetoxy-2-azetidinone. technical background [0002] 4-Acetoxy-2-azetidinone (4-AA for short), CAS: 28562-53-0, its chemical structural formula is: [0003] [0004] 4-AA is a key intermediate of a new type of carbapenem antibiotics, and is also a key intermediate for the preparation of β-lactamase inhibitors or some new anti-tumor drugs. It has a wide range of uses, but there is no such product in China. As for the literature report on synthesis, foreign literatures about its synthesis mainly include US Patent No. 3,663,535 and Organic Syntheses, 65, 135-9, 1987. Among them, the U.S. Patent No. 3,663,535 adopts a two-step reaction. The first step of the ring-forming reaction uses an excessive amount of vinyl acetate as the reaction solvent. The temperature of the entire dropwise addition a...

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Problems solved by technology

[0004] 4-AA is a key intermediate of a new type of carbapenem antibiotics, and is also a key intermediate for the preparation of β-lactamase inhibitors or some new anti-tumor drugs. It has a wide range of uses, but there is no such product in China. The literature reports on the synthesis aspect, the foreign literatures about its synthesis mainly include US Patent US3663535 and Organic Syntheses, 65, 135-9, 1987

We have found through many tests in the laboratory that when the temperature of the aqueous solution is lowered below 0°C, there are more undissolved solids and agglomerated solids precipitated by freezing, which leads to great resistance to stirring when the dropwise addition reaction is started. Stirring is very difficult, and sufficient stirring cannot be achieved. Therefore, the reaction temperature is difficult to control, there are many side reactions, and the yield is very low. If this process is used for industrial production, ordinary equipment cannot stir normally, and special equipment is required; in addition, after the reaction is completed When post-processing, because the brine solution is very thick and there are many solids, the boundaries of the layers are unclear and difficult to separate, and according to the US patent, it is necessary to use a large amount of starting material vinyl acetate as a solvent extraction8 Only once can the complete extraction be ensured, which not only consumes more and more expensive material vinyl acetate, the layering is not easy to operate, but also makes the post-processing trivial and troublesome, the product yield is affected, and the cost is increased; again, in the final product On purification, the U.S. patent has adopted high temperature (95 ℃) high vacuum distillation (10 -3 torr) method, because the product itself is not too stable, it is easy to decompose and produce impurities under high temperature, which will also lead to a decrease in yield on the one hand, poor product quality, and higher energy consumption on the other hand

Organic Syntheses, 65,135~9, in 1987 document, also exist in the second step reaction process and stir difficulty, be difficult to industrialization, and the problem such as yield is not high, and also must lower reactant temperature after the first step reaction finishes to -40°C, which increases the difficulty of industrialization, and finally, when the product is purified, it is treated with n-hexane and then frozen into a solid. The final product is not easy to crystallize, the product quality is not high, and the yield is only about 44%.

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