Felix J. Parodi

Sesquiterpenes and thiarubrines from Ambrosia trifida and its transformed roots

Abstract The roots of giant ragweed ( Ambrosia trifida ) afforded β-farnesene, β-bisabolene and squalene. In addition, thiarubrine B and its related thiop

Studies on the biosynthesis of thiarubrine A in hairy root cultures of Ambrosia artemisiifolia using 13C-labelled acetates

Abstract The 13C NMR spectra of thiarubrine A and B have been completely assigned. In a biosynthetic study using hairy root cultures of Ambrosia artemisiifolia, the 13C NMR spectra of thiarubrine A labelled by incorporation of [1-13C]-, [2-13C]- and [1,2-13C2]-acetate showed patterns of enrichment consistent with a biosynthetic pathway in which the 13-carbon 1,2-dithiin arises from a longer-chain precursor, most likely a 14-carbon homologue, by carbon-carbon scission.

Guaianolides from Baccharis salicina

Abstract Chemical analysis of Baccharis salicina afforded two new guaianolides, bacchariolides A and B, and the known flavone centaureidin. Their structures were elucidated by spectroscopic methods.

Jamaicolides A-D, four sesquiterpene lactones from Calea jamaicensis

Abstract Chemical analysis of Calea jamaicensis , the type species for the genus Calea , yielded in addition to a chromene and two flavonoids, four new sesquiterpene lactones, jamaicolides A-D, which include two guaianolides, a heliangolide, and a 12,8α-germacranolide. The structures of the new compounds were established by spectroscopic methods.

The first biomimetic conversion of a germacrolide-4-epoxide into a xanthanolide

Boron trifluoride catalysed cyclization of the germacrolide-4-epoxide dihydroparthenolide (1) provided two known guaianolides and the xanthanolide (4), the latter transformation representing the first biomimetic conversion of a germacrolide into a xanthanolide.

Complete Carton-13 Assignments of the Sesquiterpene Lactone 11,13,-Dihydroparthenolide Using 2D-Inadequate

Abstract The complete 13C NMR resonances for the sesquiterpene lactone 11,13-dihydroparthenolide were established by the application of 2D-INADEQUATE.

Heteronuclear Relayed Correlation NMR Spectroscopy of a Guaianolide 1(10)-Epoxide

Abstract Complete 13C NMR resonance assignments of a guaianolide 1(10)-epoxide were performed by the use of 2D Heteronuclear Relayed NMR Spectroscopy. This technique allowed detection of connectivities between carbons and directly attached protons and concomitant correlations between vicinal protons.

Stereochemical Study of Desacylguayulin a Using Modern NMR Techniques

Abstract The relative configuration and solute conformation of desacylguayulin A was established using modern NMR techniques. Application of COSY, NOESY, CONOESY, homo- and heteronuclear J-resolved, DEPT and NOEDIFF allowed assignments of all 1H and 13C NMR resonances.

Biomimetic Transformations of a Guaianolide-L(10)-β-Epoxide and the Molecular Structures of Three Guaianolides

Abstract A reinvestigation of the boron trifluoride-mediated transformations of the guaianolide-1(10)-β-epoxide [1] provided the previously obtained cis-eudesmanolide [5] and the fluoroguaianolide [2] as well as two new lactones, the trans-guaianolide [4] and the cis-guaianolide [3]. The molecular structures of compounds 1, 3, and 4 were determined by single crystal X-ray diffraction. The mechanisms of formation of the four lactones from epoxide 1 can be formulated via the carbocationic intermediates A and B.