Study On Synthesis Preparation Of GCLE

With the development of fermentation technique, the cost of penicillin has been reduced more, based on the similar of penicillin and cephalosporin, it has become the subject that people concern generally from penicillin to cephalosporin with chemical conversion.GCLE is another new and important intermediate to synthesize medication of cephalosporin besides 7-ACA and 7-ADCA. We can synthesize all manner of cephalosporin derivatives from GCLE. With the increase of product mix of domesticβ-lactamase modified 3-location antibiotic, as well as the improvement of GCLE's production process, GCLE will have large market. The application of GCLE, the study status, the synthesize technology and the prospect were introduced in this paper. We use the penicillin as starting material through oxidation, esterification, ring enlargement, deoxidation and halogenation and so on.The synthetic route starts from penicillin G, peroxyacetic acid(8.5%) as Oxidizing Agent to get penicillin G sulfoxide; esterifided with p-nitrobenzyl bromine to synthesize penicillin G sulfoxide ester; we synthesize 3-exomethylenecepham sulfoxide ester with phthalimide potassium and 4A molecular sieve as acid scavenger to open the ring, SnCl₄ as catalyzation to close the ring. The yield is over 60%. This synthetic route enhanced the yield, at the same time it has many excellence: gentle reaction condition, operation is simple and save, fitting the industrialization. The structures of mentioned product were confirmed by IR, ¹HNMR, physics analysis etc to be basically consistent with those of target products.We also attempt other method, which is using Morin conversion to get ring enlargement product, we find bad reproductivity, which is not conducive to productivity. At the same time, we attempt to deoxidize the ring enlargement production, use toluene as solvent, PCl₃ as chlorating agent, spasmolytol as organic base, changed organic base and solvent, reacted in low temperature to complete the preparation of 3- exomethylenecepham eicosanoic acid ester. But the result is not ideal, so we should continue to search the process.