Studies On The Syntheses Of Oligosaccharides Related To Serratia Marcescens

The O-antigen of bacterial LPS is particularly important because these parts act as antigenic determinant, that are valuable marhers of bacter infection. Syntheses of 0-oligosaccharides, which are such specific, are of present one of the importance of carbohydrate chemistry. Serratia marcercens, once were thought to be a kind of harmless gram-negative bacteria, widely distributed in soil, water and on the surfaces of plants. However, the clinic results have shown that they take responsibility for a number of serious infection in hospitals in recent years.Firstly we have synthesized 04 antigen of Serratia marcescens, then starting from L-rhamnose, glucose and gluNH₂·HCl, we have synthesized two pentasaccharide related to S. marcescens through more than thirty steps by using a series of protection, deprotection, anomeric activation and glycosylation. We have used trifluoroacetoxyl as a C-1 leaving group developed and studied in our laboratory for the glycosylation to successfully synthesize the disaccharide 26 because its donor's activity is low. We have used the inversion procedure (IP) method to synthesize the two trisaccharides 48 and 49 in good yields. Except that we have also used trichloroacetimide as an alternative method in the glycosylation steps. We have synthesized fifty-six saccharides including thirty-three monosaccharides, fifteen disaccharides, seven trisaccharides, and two pentasaccharides. The structures of all compounds were characterized by ¹H-NMR, ¹³C-NMR, 2D-NMR, IR, FAB-MS, and TOF-MS.