Sedum alkaloids-VI : Resolution enhanced proton NMR and 13C NMR spectroscopic studies on the solution conformation of Sedum acre alkaloids

The preferred solution conformation of 9 Sedum alkaloids and derivatives (sedinine, dihydrosedinine. 8-episedinine, diacetylsedinine, sedinone, 2-episedinone, sedacrine, 2-episedacrine and sedacryptine) was established by high resolution ¹H and¹³C NMR spectroscopy. These compounds may be divided into three classes based on the existence or the absence of an intramolecular hydrogen bond between the nitrogen atom and the hydroxyl group at C8 or at C10. In all of them (except sedacryptine) the N-CH₃ group was found to be axially oriented.