. Then,
H-3, 15 and 16 were further assigned to be α-orientation by proposed
biosynthesis of compound 1 from strictamine (5) (Scheme 1) [20–22],
which were identical those of normavacurine. Furthermore, NOE correlation
of δH 1.67 (H3-18)/3.81 (H-15) in its ROESY spectrum, indicated E
configuration for the double bond of C-19/20 as normavacurine. Thus,
compound 1 was elucidated to be a Strychnos-alkaloid, normavacurine-
21-one