Study Of Stereoselective Synthesis Of α-deoxyglycoside And Synthesis Of Marine Nature Product Marangucycline B

Deoxysugar is a component of many natural products and plays an important role in many biological processes.The stereoselective synthesis of deoxyglycosides remains one of the biggest challenges in carbohydrate chemistry.Marangucycline B,which contains deoxysugar structural units and show good antitumor activity,is a marine natural product isolated from Streptomyces sp.SCSIO 11594 in recent years.And we explore the method of stereoselective synthesis of deoxyglycoside bonds and synthesis of Marangucycline B,a marine natural product containing deoxyglycoside bonds.The thesis is divided into three parts:1.Cu（II）catalyzed stereoselective synthesis of 2-deoxygalactoside.In this part,synthetic approach to 2-deoxygalactosides was developed with per-benzylated galactal as a raw material and Cu Br₂as an easily available catalyst.This method had a wide range of substrates,including not only alcohol acceptors,amino acid acceptors,sugar acceptors and phenol acceptors,but also galactal donors protected by different protective groups.At the same time,it also had the advantages of using small amount of catalyst（5 mol%）,mild reaction conditions（at room temperature）,short reaction time（1-3 h）,moderate to good reaction yields（61～95%）and high stereoselectivity（α:β>30:1）.What’s more,the trisaccharide was successfully synthesized through this method,which provided a new method for the synthesis of other oligosaccharides containing singleα-deoxyglycoside.2.Study on stereoselective synthesis of HMF-Enulosides.In this part,a magnetic magnetic nano Fe₃O₄@C@Al（III）catalyzed Ferrier rearrangement reaction between peracetylated glycal donor and HMF acceptor was developed.Seven kinds of HMF-2,3-unsaturated glycoside compound were synthesized with 59～91%yield and the selectivity of the product wereα:β=16:1～>30:1,which solved the problem of the selectivity was not single in the current method synthesis of HMF-2,3-unsaturated glycoside compounds.After deprotection of the obtained product,six kinds of HMF-2,3-unsaturated sugar alcohol compounds were obtained,and the selectivity of the product did not change.Finally,the deacylated products were selectively oxidized,and four HMF-Enulosides compounds were obtained with single selectivity,which realizing the stereoselective synthesis of HMF-Enulosides compounds.3.Study on synthesis of marine natural product marangucycline B.Marine natural product Marangucycline B is a new compound with anti-tumor activity containing deoxyglycoside structural units isolated and extracted from Streptomyces marinus in recent years.In this section,the synthesis of Marangucycline B was preliminary explored.Using 2,6-dideoxyglucose donor,1,5-dihydroxynaphthol and2,5-dimethyl-4-methoxybromobenzene as starting materials,the dienophiles and dienosomes used in the construction of key tetracyclic intermediates by Diels-Alder ring closure reaction were synthesized separately.