Design,Synthesis And Bioactivity Of Carbohydrate Natural Products And Derivatives

This paper was mainly about novel pesticide discovery based on carbohydrates,which possess structure variability,good environment compatibility and excellent bioactivities.Three parts were contained in this paper:Design,synthesis and bioactivities of novel carbohydrate modified macrolactam.Synthesis studies of natural product Orsellide C and its oxime ester derivatives;Synthesis studies of natural oligosaccharides related to certain biological activities.Part I:Design,synthesis and bioactivities of novel carbohydrate modified macrolactams derivatives.Fluvirucins are bioactive macrolactam glycosides isolated from actinomycetes.All these compounds were found to exhibit antifungal activity against various strains of Candida sp.?dermatophytes?influenza A virus and anthelmintic activity.However,tedious synthetic steps limit its application in agricultural production.Therefore,we paid considerable attention to the design,synthesis and activity evaluation of fluvirucins derivatives as potential pesticides.First,3-azido-3,6-deoxy-L-talofuranose was prepared using D-glucose as the starting material.And 3-Azido-3,6-deoxy-L-talofuranose modified pentadecanlactam derivatives were obtained by the coupling of 3-azido-3,6-deoxy-L-talofuranose donor and macrolactams acceptor.The rest of the carbohydrate modified macrolactams derivatives were obtained by the same way.The initial bioactivity results were studied.Part ?:Synthesis studies of natural product Orsellide C and its oxime ester derivatives The antibacterial orsellides A-E,novel esters consisting of orsellinic acid and a 6-deoxyhexose,isolated from Chaetomium sp.(strain Go 100/9)are rare examples for fungal metabolites containing deoxyhexose building blocks that are normally characteristic for bacterial secondary metabolites.An efficient method was developed for the derict synthesis of this 6-deoxyhexose from commercially available L-rhamnose,and its application in the synthesis of natural product Orsellide C and its oxime ester derivatives.Thirty novel carbohydrate modified oxime ester derivatives were designed and synthesized from commercially available L-rhamnose as the starting materials.The structures of the target compounds were characterized by 1H NMR?13C NMR and MS.The original fungicidal activities results showed that some of the compounds exhibited good fungicidal activities against 8 kinds of pathogenic germs at the concentration of 50 ?g/mL.Part ?:Synthesis of high-mannose-type 3,6-branched mannosaccharides related to N-Glycans 2,3-O-Isopropylidene-?-D-mannopyranosides are important building blocks in the synthesis of mannose-containing derivatives,methods have been reported for the preparation of these compounds.In this paper we developed a direct and regioselective 2,3-O-isopropylidenation of ?-D-mannopyranosides method,and its application in the synthesis of mannose oligosaccharides.Three High-Mannose-Type 3,6-branched mannosaccharides related to N-Glycan were synthesized using Alloc as key protection group,The structures of target compounds and intermediates were characterized by 1H NMR,13C NMR,and HRMS.