Structure and synthesis of new natural heteroyohimbine N-oxides

Abstract Natural 4,R-akuammigine N-oxide, (1) 4,S-akuammigine N-oxide, (2) and 4,R-tetrahydroalstonine N-oxide (3) have been isolated from species of Uncaria. (Rubiaceae). Their stereochemistry has been established from NMR spectra. Synthesis of 1,2,3 and of 4,R-ajmalicine N-oxide and 4,R-3-isoajmalicine N-oxide by peracid oxidation of the bases is described.