FIRST DIRECT AND DETAILED STEREOCHEMICAL ANALYSIS OF STRICTOSIDINE

Using the easy lactamization of vincoside (4), epimer-free strictosidi ne (1) was prepared from secologanin (2) and tryptamine (3). 2D NMR me thods were used to determine unambiguously the H-1- and C-13-NMR chemi cal shifts, the H-1-H-1 and C-13-H-1 coupling constants, and the H-1-H -1 NOE interactions in strictosidine (1). A minimal number of spectros copic parameters (11 coupling constants, 3 NOEs) and some theoretical considerations have made it possible to select the single species of t he 648 selected stereoisomers and to confirm directly the S configurat ion at the newly formed C-3 chiral center, the P helicity of the dihyd ropyran and tetrahydropyridine rings, and the conformations around C-1 4 and the glycosidic bridge.