Minor Constituents of Lippia integrifolia

Abstract

Three new sesquiterpenes (1-3) possessing the 2,6,6,9-tetramethyltricyclo[5 .4.0.0Z'*]undecane (lippifoliane) skeleton were isolated as minor constituents of Lippia integrifolia. Their structures and stereochemistry were elucidated from nmr data including double resonance experiments, COSY, and nOe, and by comparison of their "C-nmr spectra with those of lippifoli-1 (6)-en-5 -one.Following the studies on the chemical constituents of the aromatic shrub Lippiu integrifoo(iu (Griseb.) Hieron (Verbenaceae) (1-5), we report herein the isolation, structure elucidation, and full spectral analyses of three new substances 1-3 found as minor components in the essential oil of this plant. These tricyclic sesquiterpenes are structurally related to lippifoli-1(6)-en-5-one 141, previously isolated as one of the major constituents (2,3). RESULTS AND DISCUSSIONCompounds 1 and 2 showed [MI' at mlz 236 in agreement with the molecular formula CI5H2*O2. The 'H-nmr spectra of 1 (Table 1) showed H-6 as a doublet (J=ca.

Sesquiterpenes from Lippia integrifolia Essential Oil

“…Partial catalytic hydrogenation of africa-1,5-diene (3) also afforded 2 and 7 (identified by GC-MS). The relative configurations of 2, 3, and 7 were thus confirmed by correlation with isoafricanol (6). Unfortunately, the absolute configuration is still unknown.…”

“…The structure of 5 was verified by 2D NMR techniques ( 1 H-1 H COSY, HMQC, HMBC, and NOESY). Catala `n et al reported the isolation of 3R-hydroxy-6-asteriscene from L. integrifolia 6 with a cis configuration of H-2 and H-9 (based on the large coupling constant of 11.0 Hz), as is the case in asteriscanolide, which has been studied by X-ray diffraction. 13 The coupling constant of 10.7 Hz between H-2 and H-9 observed in 5 (see the 1…”

Chemical composition, seasonal variation and a new sesquiterpene alcohol from the essential oil of Lippia integrifolia

“…Identification of the individual components was based on (a) computer matching with commercial mass spectra libraries (NBS75K, NIST, WILEY), [15][16][17] comparison with spectra available in our files [5][6][7][8]11,12 and literature data; [13][14][15][16][17][18] (b) comparison of their GC retention indices (RI) on an HP-5 column.…”

“…a Identification by comparison with mass spectrum reported in the literature 13. b Identification by comparison with mass spectra reported in the literature5,7,11,12,21 and in our files. c Known also as bulnesol.…”

Enantiospecific synthesis of the tricyclic core structure of lippifolianes

“…2 Subsequently, the research groups of Catalan and Joseph-Nathan reported the isolation of three more derivatives of lippifolianes 5-7, Chart 1. 3 Recently, the absolute configuration of lippifolianes along with that of the africananes have been assigned by JosephNathan et al on the basis of the analysis of circular dichroism data in combination with density functional theory minimum energy molecular models. 4 The tricyclo [5.4.0.0 2,4 ]undecane 1 was also present as an integral part in a few diterpenoids.…”