Synthetic Investigation Toward The D-Ring-Functionalized Oleanane-Type Saponins

1.Synthetic Investigation toward the D-Ring-Functionalized Cytotoxic Oleanane-Type Saponins Pithedulosides D and EAs a subunit group of oleanane-type saponins,D-ringfunctionalized oleananetype saponins are drawing increasing attention from both pharmacologists and chemists because of their outstanding bioactivities.,We decided to launch a program to investigate the synthesis of the other two D-ringfunctionalized oleanane-type saponins,Pithedulosides D and E.Which were isolated from the aerial parts of Albizia inundata and proven to possess remarkable cytotoxity against a series of cancer cell lines.Through orchestrated application of Yu and Schmidt glycosylations,the investigation has culminated in the first total synthesis of Pithedulosides D and E.Benefitting from the applied convergent synthetic strategy,the echinocystic acids could be synthesized in overall yields of as high as 71 and 76 % through four linear steps.2.The sythetic exploration toword the D-Ring-Functionalized Oleanane-type Saponins Concinnoside C and DBased on the previous synthesis study of the oleanane-type triterpene saponins Pitheduloside D and E,we interested in the other two compounds of this familyConcinnoside C and D.By screening experimental conditions,the extraction efficiency of the protoescigens has been improved.Under the current theoretical knowledge of organic synthesis,a reasonable experimental route was designed to explore the transformation of six different hydroxyl groups of the protoescigen,which provided the foundation for the completion of the non-commercial acacic acid lactone.The exploration of novel ortho-(para-methoxyphenylethynyl)phenyl(MPEP)donor ‘s application in glucosamine and arabinose,which has accumulated the experience of its substrate scopes.