28890-02-0Relevant academic research and scientific papers
Revisiting the Chemistry of Guaiacwood Oil: Identification and Formation Pathways of 5,11- and 10,11-Epoxyguaianes
Tissandié, Lo?c,Gaysinski, Marc,Brévard, Hugues,Meierhenrich, Uwe J.,Filippi, Jean-Jacques
, p. 526 - 537 (2017/03/09)
Guaiacwood oil from Bulnesia sarmientoi Lorentz ex. Griseb is a common natural ingredient of the perfume industry used in both domestic and luxury fragrances for its highly appreciated woody-rosy odor, as well as its excellent fixative properties. Despite its long and traditional use as a perfume ingredient, guaiacwood oil has not been extensively studied. Thus, the chemical characterization of its constituents by using a full array of GC-hyphenated techniques (GC-MS, GC × GC-MS, and pc-GC) combined with conventional chemical fractionation was undertaken. In the course of this work, 15 new sesquiterpenoids mostly belonging to the 5,11- and 10,11-epoxyguaiane families were identified. Each isolated compound was fully characterized by NMR and MS. Collectively, the specific chemical relationships observed between sesquiterpene oxides and alcohols permitted the formulation of probable formation pathways regarding their presence as natural constituents of guaiacwood extracts.
Doubly deuterium-labeled patchouli alcohol from cyclization of singly labeled [2-2H 1]farnesyl diphosphate catalyzed by recombinant patchoulol synthase
Faraldos, Juan A.,Wu, Shuiqin,Chappell, Joe,Coates, Robert M.
experimental part, p. 2998 - 3008 (2010/05/01)
Incubations of isotopically pure [2-2H1](E,E)- farnesyl diphosphate with recombinant patchoulol synthase (PTS) from Pogostemon cablin afforded a 65:35 mixture of monodeuterated and dideuterated patchoulols as well as numerous sesquiterpene hydrocarbons. Extensive NMR analyses ( 1H and 13C NMR, 1H homodecoupling NMR, HMQC, and 2H NMR) of the labeled patchoulol mixture and comparisons of the spectra with those of unlabeled alcohol led to the conclusion that the deuterium label was located at positions (patchoulol numbering system) C5 (both isotopomers, ca. 100%) and C12 (minor isotopomer, 30-35%), that is, an approximately 2:1 mixture of [5-2H1]- and [5,12- 2H2]-patchoulols. Low-resolution FIMS analyses and isotope ratio calculations further corroborated the composition of the mixture as mainly one singly deuterated and one doubly deuterated patchoulol. From a mechanistic point of view, the formation of [5,122H2] patchoulol is rationalized through the intermediacy of an unknown exocyclic [7,10:1,5]patchoul-4(12) ene (15-d1), which could incorporate a deuteron at the C-12 position on the pathway to doubly labeled patchoulol. The corresponding depletion of deuterium content observed in the hydrocarbon coproducts, β-patchoulene and α-guaiene (55% d0), identified the source of the excess label found in patchoulol-d2. Comparison of the PTS amino acid sequence with those of other sesquiterpene synthases, and examination of an active site model, suggested that re-orientation of leucine 410 side chain in PTS might facilitate the creation of a 2-pocket active site where the observed deuteron transfers could occur. The retention of deuterium at C5 in the labeled patchoulol and its absence at C4 rule out an alternative mechanism involving two consecutive 1,2-hydride shifts and appears to confirm the previously proposed occurrence of a 1,3hydride shift across the 5-membered ring. Anew, semisystematic nomenclature is presented for the purpose of distinguishing the three different skeletal structures of the patchoulane sesquiterpenes.
