Enantiomeric composition and prevalence of some bicyclic monoterpenoids in amber

Abstract

Among the more prevalent chiral monoterpenoid compounds in conifers are α‐pinene, β‐pinene, and smaller amounts of camphene and limonene. The most prevalent chiral monoterpenoid compounds in fossilized resin (referred to as amber in this paper) appear to be borneol, isoborneol, and camphene. Most of these compounds have easily measured enantiomeric excesses. The borneol and isoborneol in some amber samples have pronounced enantiomeric excesses despite the fact that they are tens of millions of years old. The enantiomeric ratios of the monoterpenoids in different ambers vary tremendously and often are distinct. However, in any single amber sample, the stereochemistry (absolute configuration) of the excess monoterpenoid enantiomers appears to be identical. The camphene in amber may be a secondary reaction product formed over time, possibly from the dehydration of borneol. Although a compound's original stereochemistry can be preserved, it also may diminish with the number and type of chemical transformations over geological time. The monoterpene enantiomeric ratios in modern conifer resins vary tremendously. Future stereochemical studies are outlined that could provide the data necessary for more exact geochemical interpretations and possibly for obtaining pertinent paleobiological information. © 1996 Wiley‐Liss, Inc.

Comparative transcriptomics unravel biochemical specialization of leaf tissues of Stevia (Stevia rebaudiana) for diterpenoid production

“…7E and 8C). GC-MS has proven to be effective in resolving stereoisomers of many terpenoid compounds (Armstrong et al, 1996;Huang and Armstrong, 2009). Because the peak observed in assays combining SrCPS and SrKSL has a different retention time with a similar mass spectrum as ent-copalol, we postulate that the unidentified compound could be a stereoisomer of ent-copalol.…”

History and Developments in Chromatographic Column Technology and Validation to 2001

“…Stereochemical analysis also can be of importance in 6.C. CONTRIBUTIONS BY OTHER CHROMATOGRAPHERS geochemistry [5,6,24,25], geochronology [26], biochemistry, and in some areas of materials science [7].…”

“…As in chromatography, considerable present research is now focusing on an assembly of macrocyclic building blocks to produce supramolecular structures with desired properties, including ligand-exchange processes, cyclodextrin phase arrays, enantioselective and molecular recognition as given in 13 papers on supramolecular chemistry at the 35th Midwest Regional Meeting of the American Chemical Society, Oct. [25][26][27]2000 in St. Louis, MO [2]. CE, capillary electrochromatography (CEC), and ultra-high-pressure liquid chromatography (UHPLC), which allows the use of very small particles generating plate numbers of 100,000 -200,000 or more.…”

Resolution of isoborneol and its isomers by GC/MS to identify “synthetic” and “semi‐synthetic” borneol products

“…The separation of enantiomers, (+)‐ and (−)‐ borneol as well as (+)‐ and (−)‐isoborneol by chiral gas chromatography (GC) was reported by us and other groups previously . Generally speaking, the main drawbacks of chiral column are high cost and durability.…”

“…10 The separation of enantiomers, (+)-and (−)-borneol as well as (+)-and (−)-isoborneol by chiral gas chromatography (GC) was reported by us and other groups previously. [10][11][12][13][14] Generally speaking, the main drawbacks of chiral column are high cost and durability. Our unpublished results also showed that applications of samples extracted from fermentation media or herbal ointment complexes usually led to irreversible damage of the βcyclodextrin-based chiral GC column after several runs.…”