Jafrine, a novel and labile β-carboline alkaloid from the flowers of Tagetes patula

An inherently unstable and structurally novel tetrahydro β-carboline alkaloid, (+) jafrine () was isolated from the petroleum ether extract of Tagetes patula flowers. Its structure and stereochemistry has been determined with the help of spectroscopic analysis and the synthesis of racemate, (±) jafrine starting from available (±) tetrahydroharmine (). The effect of solvent polarity on the ratio of amide rotamers of jafrine during NMR studies is discussed. The transformation of jafrine as well as 4-N-acetyl tetrahydroharmine (), into 2-acetyl tryptamine derivatives by auto-oxidation was observed and its detail is presented. This process may be used as a synthetic tool for the preparation of tryptamine derivatives.