New Sesquiterpene Lactones from Montanoa tomentosa subsp. xanthiifolia*.
A chemical examination of MONTANOA TOMENTOSA subsp. XANTHIIFOLIA afforded in addition to some known compounds, four new sesquiterpene lactones: 4beta,5alpha-epoxy-8alpha-isobutyryloxy- TRANS-germacr-1(10)-en-12,6beta-olide ( 1A), 4beta,5alpha-epoxy-7alpha-hydroxy-8alpha-isobutyryloxy- TRANS-germacr-1(10)-en-12,6beta-olide ( 1B), (1 R,4 S)-1,5-cyclo-5alpha-hydroxy-8alpha-isobutyryloxy-7alpha, 10alpha-oxagermacran-12,6beta-olide ( 2A), and 4beta-hydroxy-8alpha-isobutyryloxy-7alpha,10alpha-oxaguaian-12,6beta-olide ( 3). The structures were determined mainly by spectroscopic methods. The structure of 1B was confirmed by an X-ray analysis.
Lidia-Pérez
A
A
Instituto de Química, Universidad Nacional Autónoma de México, Ciudad Universitaria, Circuito Exterior, Coyoacán, 04510 México, D.F.
Caballero
M B
MB
Ortega
A
A
Gaviño
R
R
de Vivar
A R
AR