title: New Sesquiterpene Lactones from Montanoa tomentosa subsp. xanthiifolia*.
abstract: 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.
authors.affiliation: Instituto de Química, Universidad Nacional Autónoma de México, Ciudad Universitaria, Circuito Exterior, Coyoacán, 04510 México, D.F.
authors.forename: A
authors.initials: A
authors.lastname: Lidia-Pérez
authors.forename: M B
authors.initials: MB
authors.lastname: Caballero
authors.forename: A
authors.initials: A
authors.lastname: Ortega
authors.forename: R
authors.initials: R
authors.lastname: Gaviño
authors.forename: A R
authors.initials: AR
authors.lastname: de Vivar