Synthesis of Two Natural Oleanolic Acid Saponins

3‐ O ‐[ β ‐ D ‐Glucopyranosyl‐(1→3)‐ α ‐ L ‐arabinopyranosyl]‐oleanolic acid‐28‐ O ‐[ β ‐ D ‐glucopyranosyl] ester 1 was synthesized concisely by a convergent strategy. Using stepwise fashion for the synthesis of saponin 2 , 3‐ O ‐{[ β ‐ D ‐glucopyranosyl‐(1→2)]‐[ α ‐ L ‐arabinopyranosyl‐(1→3)]‐ α ‐ L ‐arabinopyranosyl}‐oleanolic acid‐28‐ O ‐( β ‐ D ‐glucopyranosyl) ester, an abnormal phenomenon, that the terminal arabinosyl residue took the 1 C 4 conformation instead of typical 4 C 1 form, was observed. Deprotection or heating could not resume the normal conformation, which resulted in the product of 2 ′ not 2 .