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Periploside A is a pregnane hexasaccharide identified from the Chinese medicinal plant Periploca sepium, which features a unique seven-membered formyl acetal bridged orthoester (FABO) motif and shows potent immunosuppressive activities. The total synthesis of this natural product is achieved in a total of 76 steps with the longest linear sequence of 29 steps and 9.2% overall yield. The FABO motif is constructed via a combination of Sinaÿ’s and Crich’s protocol for the formation of orthoester and acetal glycosides, respectively. The 2-deoxy-b-glycosidic linkages are assembled stereoselectively with judicious choice of the glycosylation methods.[2,3] The epimer at the spiro-quaternary carbon in the FABO motif has also been elaborated in a stereo-controlled manner. This epimer, as well as the synthetic analogs bearing FABO motif, retain largely the inhibitory activities of periploside A against the proliferation of T-lymphocyte, indicating the importance of the chemical connection of the FABO motif to their immunosuppressive activities.