Compound 1 was obtained as white powder. Its molecular formula
of C19H20N2O2 was established by 13C NMR and HR-ESI-MS data (m/z
309.1596 [M + H] +, calcd. for 309.1603), indicating 11 indices of
hydrogen deficiency. The UV spectrum showed the characteristic maximal
absorptions of indole alkaloid at 219 and 271 nm [18]