Novel reactions of lycoctonine analogs: unusual pyrolysis of C4–COOH and hydrogenolysis of N–C6 bond

Pyrolysis of carboxylic acid group at C-4 of 2, an oxidation product from the C19-diterpenoid alkaloid lycoctonine 1, generated an unexpected but novel rearranged product 13 (37%). The structure of 13 was confirmed by its 2D NMR data and its single crystal X-ray crystallographic analysis. In addition, hydrogenolysis of 13 in the presence of acetic acid yielded the N–C6 bond fission products 16 and 17, which represents the first hydrogenolysis involving the breakage of the N–C6 bond of the diterpenoid alkaloids. Some new observations on the oxidation of lycoctonine 1 were described as well.