Study Of Synthesis Of C-3 Branched Azasugars And Deprotection Of N-t-Butyloxycarbonyl Group Mediated By Selectfluor

This thesis consists of two sections.The first section is the study on the synthesis of C-3 branched derivatives with branched polyhydroxylated cyclic nitrone as the key intermediate,and the second part is the study of the efficient and high selective removal of N-t-butyloxycarbonyl group mediated by selectfluor.1.Study of synthesis of C-3 branched azasugarsAzasugars have important applications in the treatment of diabetes,cancer and viral infection due to their potent inhibitory activities against glycosidases.In this study,the 1,4-dideoxy-1,4-imino-L-xylitol skeleton structure was selected as the research object.With branched cyclic nitone as key intermediate,synthesis of a series of branched derivatives can be realized with high efficiency and selectivity.In this thesis,1,2:5,6-di-O-isopropylidene-?-D-glucofuranose was first oxidized to ketone,and then put under Grignard addition to afford compound 2-12.Configuration of the newly introduced methyl group was confirmed as S.The nitrone precursor 2-29 was then obtained after selective hydrolysis and conversion of the protective groups.Based on precursor 2-29,the first synthesis of the C-3 branched nitrone was finally successfully realized after a series of trials,and used as the key intermediate in the synthesis of the branched azasugar 2-32.??Efficient and Chemoselective Deprotection of N-t-Butyloxycarbonyl Group Mediated by SelectfluorSelectfluor is a widely used fluorinated reagent.To explore new functions of the reagent,it is very important to discover and understand its reaction characteristics. Based on stoichiometric selectfluor,selective removal of single N-t-butyloxycarbonyl group of the N-double protected amino acids was achieved for the first time.Compared with other methods,the deprotection method has the advantages of simple operation,high efficiency and high selectivity.Its application value has been expanded and verified in the deprotection reaction of a series of amino acid derivatives,and has helped to successfully realize the synthesis of purine derivatives that have potential applications in medicine.