Differentiation between 3,4- and 4,15-Epoxyeudesmanolides by Electrospray Ionization Tandem Mass Spectrometry

Table 1

Assignments of the main product ions of the protonated epoxyeudesmanolides 1 and 2 and their respective relative intensities.

Assignment	1	2
A ([M + H]^+)	365 (31)/368	379 (29)/381
B (A − R1OH)	263 (40)/264	263 (23)/264
C (B − H2O)	245 (100)/245	245 (100)/245
D (B − CO)	235 (12)/236	—
E (C − H2O)	227 (87)/227	227 (42)/227
F (C − CO and D − H2O)	217 (62)/218	217 (19)/218
G (E − H2O)	209 (<5)/
H (E − CO and F − H2O)	199 (67)/199	199 (81)/199
I (F − CO)	189(5)/	189 (<5)/
J (H − H2O)	181 (56)/181	181 (21)/181
K (H − CO)	171 (21)/	171 (23)/
L (I − CO)	145 (10)/

Relative intensity lower than 5%. The relative intensities are given between parentheses. Data from the experiments with labelled hydrogen ([M + 4D]⁺ for 1 and [M + 3D]⁺ for 2) are given after bars.