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.