| Proteus belongs to intestinal bacteria and is one of the three bacterial pathogens that pose the greatest threat to human health announced by the World Health Organization in 2017.Their antibiotic resistance determines the urgent need to develop vaccines against these pathogens at present.This paper describes the first total synthesis of the common O-antigen(one,two,and three repeat units of the trisaccharide fragment)of Proteus mirabilis OE and Proteus vulgaris TG103.In this paper,the glycosylation reaction is carried out by selenoside donor and alkynyl ester donor,good selectivity and yield can be obtained.After the replacement of the linker of the terminal sugar chain,the adjustment of one of the acetoxy groups of the trisaccharide donor,and the adjustment of the order of deprotection,the optimal deprotection route was finally determined after repeated attempts.Finally,the target molecule was successfully obtained,it consistent with known natural product data reported in the literature.Bordetella Hinzii,a genetic relative of Bordetella pertussis,is at risk of zoonosis in humans and can spread continuously from person to person.It has important research significance.The O-antigen structure of Bordetella Hinzii ATCC 51730 contains Glc NAc3 NAc AN(2,3-di-acetamido-2,3-di-deoxy-glucuronamide)and Gal NAc3 NAc AN(2,3-di-acetamido-2,3-di-deoxy-galacturonamide).However,2,3-dideoxy-2,3-di-aminosugar is a scarce sugar and its efficient synthesis is challenging.Therefore,we developed a two-step one-pot method to obtain pyranoid 3-azido-2-nitro-1,2-cis-glycoside products from 2-nitro-glycal as raw materials,and then obtained 2,3-di-deoxy-2,3-di-aminosugars by reduction.This method has mild condition,high overall efficiency and wide application.We also applied this method to synthesis Oantigen of Bordetella hinzii ATCC 51730.We have already obtained key trisaccharide intermediate,which can be used for complete the total synthesis of trisaccharide and tetrasaccharide repeat unit. |
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