A Simple, Convenient and Expeditious Approach to Cineol

Bugarčić, Živadin D.; Dunkić, Jelena D.; Mojsilović, Biljana M.

doi:10.1002/chin.200507178

Cited by 7 publications

(16 citation statements)

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“…Eucalyptol synthesis has so far only been realized by subjecting the preformed cyclic α-terpineol either to harsh acidic conditions 21 or by employing a two-step procedure via phenylselenoetherification. 22 The mechanism of the eucalyptol formation (Scheme 1a) from NOH (18) within I was studied in more detail. After the formation of the key intermediate α-terpineol (3-OH), the C-C double bond has to be activated via protonation to initiate the second cyclization (Scheme 2a, grey box).…”

Section: Resultsmentioning

confidence: 99%

Terpene Cyclizations inside a Supramolecular Catalyst: Leaving-Group-Controlled Product Selectivity and Mechanistic Studies

et al. 2017

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The tail-to-head terpene cyclization is arguably one of the most complex reactions found in nature. The hydrogen-bond-based resorcinarene capsule represents the first man-made enzyme-like catalyst that is capable of catalyzing this reaction. Based on noncovalent interactions between the capsule and the substrate, the product selectivity can be tuned by using different leaving groups. A detailed mechanistic investigation was performed to elucidate the reaction mechanism. For the cyclization of geranyl acetate, it was found that the cleavage of the leaving group is the rate-determining step. Furthermore, the studies revealed that trace amounts of acid are required as cocatalyst. A series of control experiments demonstrate that a synergistic interplay between the supramolecular capsule and the acid traces is required for catalytic activity.

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Section: Resultsmentioning

confidence: 99%

Terpene Cyclizations inside a Supramolecular Catalyst: Leaving-Group-Controlled Product Selectivity and Mechanistic Studies

et al. 2017

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“…Following the description of Bugarčić et al [13] for the unlabeled compound, H 3 ]-a-terpineol (2, 50 mg; 0.32 mmol) and pyridine (28 mg, 0.34 mmol) were dissolved in 2 mL anhydrous dichloromethane and phenylselenyl chloride (69 mg; 0.34 mmol) was added at room temperature. The solution was stirred for 1 h and was then successively washed with HCl (1 mol/L, 3 Â 2 mL), saturated NaHCO 3 (2 Â 2 mL) and brine.…”

Section: Synthesis Of [9-2 H 3 ]-18-cineole (4)mentioning

confidence: 99%

“…The latter was dissolved in toluene (20 mL), extracted with water and the combined aqueous extracts were re-extracted with dichloromethane. The dichloromethane phases were combined, dried over Na 2 SO 4 (13).…”

Section: Synthesis Of Unlabeled 9-hydroxy-18-cineolementioning

confidence: 99%

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Quantification of 1,8‐cineole and of its metabolites in humans using stable isotope dilution assays

Horst

Rychlik

2010

Molecular Nutrition Food Res

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The metabolism of 1,8-cineole after ingestion of sage tea was studied. After application of the tea, the metabolites 2-hydroxy-1,8-cineole, 3-hydroxy-1,8-cineole, 9-hydroxy-1,8-cineole and, for the first time in humans, 7-hydroxy-1,8-cineole were identified in plasma and urine of one volunteer. For quantitation of these metabolites and the parent compound, stable isotope dilution assays were developed after synthesis of [(2)H(3)]-1,8-cineole, [9/10-(2)H(3)]-2-hydroxy-1,8-cineole and [(13)C,(2)H(2)]-9-hydroxy-1,8-cineole as internal standards. Using these standards, we quantified 1,8-cineole by solid phase microextraction GC-MS and the hydroxyl-1,8-cineoles by LC-MS/MS after deconjugation in blood and urine of the volunteer. After consumption of 1.02 mg 1,8-cineole (19 μg/kg bw), the hydroxycineoles along with their parent compound were detectable in the blood plasma of the volunteer under study after liberation from their glucuronides with 2-hydroxycineole being the predominant metabolite at a maximum plasma concentration of 86 nmol/L followed by the 9-hydroxy isomer at a maximum plasma concentration of 33 nmol/L. The parent compound 1,8-cineole showed a low maximum plasma concentration of 19 nmol/L. In urine, 2-hydroxycineole also showed highest contents followed by its 9-isomer. Summing up the urinary excretion over 10 h, 2-hydroxycineole, the 9-isomer, the 3-isomer and the 7-isomer accounted for 20.9, 17.2, 10.6 and 3.8% of the cineole dose, respectively.

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“…The procedure works smoothly resulting in quantitative formation of the cyclic ethers. Prompted by this finding, we considered it synthetically interesting and profitable for our purposes to extend this method to other representative alkenols in order to describe a general procedure for a rapid and efficient cyclization reaction of alkenols with phenylselenyl halides [25,26]. Various substituted tetrahydrofuran and tetrahydropyran rings were obtained that depended on the structure of the starting alkenols.…”

Section: Resultsmentioning

confidence: 98%