- THE OCTANT RULE. XVI. CONFORMATION AND CIRCULAR DICHROISM OF SYN AND ANTI 2-METHYLBICYCLOHEXAN-3-ONES, THUJONE AND ISOTHUJONE
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(1S,5S)-exo-2(R)-Methylbicyclohexan-3-one (1) and (1S,5S)-endo-2(S)-methylbicyclohexan-3-one (2) were synthesized and their circular dichroism (CD) spectra run.Conformational analysis based on molecular mechanics calculations and Karplus equation analyses of vicinal H/H NMR coupling constants indicate boat-like sofa conformations for both 1 and 2, with very little ring distortion from the symmetry of the parent bicyclohexan-3-one.The lone dissymmetric ψ-axial and ψ-equatorial methyl groups of 1 and 2, respectively, are both octant consignate.The natural product analogs of 1 and 2, (-)-3-isothujone (3) and (+)-3-thujone (4) were prepared and examined similarly.Their α-methyl perturbers dominate the CD n-?* Cotton effects.
- Lightner, David A.,Pak, Chwang Siek,Crist, B. Vincent,Rodgers, Stephen L.,Givens, John W.
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- A six-step total synthesis of α-thujone and: D 6-α-thujone, enabling facile access to isotopically labelled metabolites
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The short synthesis of α-thujone relies on the functionalization of the readily available dimethylfulvene. Furthermore, the three main metabolites of the natural product were also synthesized. Since d6-acetone can be used as a starting material, the route developed allows for the facile incorporation of isotopic labels which are required for detecting and quantifying trace amounts via GC/MS analysis.
- Thamm, Irene,Richers, Johannes,Rychlik, Michael,Tiefenbacher, Konrad
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p. 11701 - 11703
(2016/10/04)
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- Kinetics of thermal rearrangements in the Δ2-thujene system: A full quadrisection of a perturbed bicyclo[3.1.0]hex-2-ene
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Further insight into the behavior of suppositional diradicals in a caldera is sought in the thermal rearrangements among the four "Δ 2-thujenes", two 1-isopropyl-4-methylbicyclo[3.1.0]hex-2-enes [(-)-cis-1 and (+)-trans-2] and two isomers, exo- and endo-3-isopropyl-6- methylbicyclo[3.1.0]hex-2-ene [(+)-exo-3 and (-)-endo-4]. Optically pure trans-3-isopropyl-5-vinylcyclopentene (5) is the final, strongly thermochemically favored product, the result of an intramolecular homodienyl shift of a methyl hydrogen atom in (-)-endo-4. The set of twelve specific rate constants, four sets of three each, that define the interrelations among the four isomers has been extracted from data acquired starting from each isomer. An attractive mechanistic hypothesis involving an, intermediate diradical of iso conformation, common, for example, to both (-)-cis-1 and (+)-exo-3 (as educts), that proceeds to an anticonformer common to both (+)-trans-2 and (-)-endo-4 does not lead to a satisfactory rationalization of the product distribution. Addition of a second mechanistic conceptual scheme, that of a diradical-in-transit behaving as if there were a measure of continuous bonding (for example, (+)-trans-2 proceeding directly to (-)-cis-1), improves agreement with experiment. Over a 30 °C range of temperature, there is no credible change in product distribution.
- Von E. Doering, William,Zhang, Ting-Hu,Schmidt, Eckhart K. G.
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p. 5688 - 5693
(2007/10/03)
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- Palladium-Catalysed Intramolecular Cyclisation of Olefinic Propargylic Carbonates and Application to the Diastereoselective Synthesis of Enantiomerically pure (-)-α-Thujone
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Intramolecular [Pd2(dba)3]/tri(2-furyl)phosphine-catalysed (dba = dibenzylideneacetone, PhCH= CHCOCH=CHPh) cyclisations of olefinic propargylic carbonates I provided alk-1-enyl-(3-aza)bicyclo[3.1.0]-hexanes VIII in good yields. A palladium cascade sequence I → II → III → IV → VII → VIII is proposed. Furthermore, chiral propargylic carbonates such as 23, 24 and 25 allowed diastereoselective formation of bicyclo[3.1.0]hexanes 29, 30 and 31, respectively. The first diastereoselective synthesis of the monoterpene, (-)-α-thujone 40 illustrates the potential of the method.
- Oppolzer, Wolfgang,Pimm, Austen,Stammen, Blanda,Hume, W. Ewan
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p. 623 - 639
(2007/10/03)
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- (-) 3 Isothujone, a small nonnitrogenous molecule with antinociceptive activity in mice
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(-) 3 isothujone and (+) 3 thujone were examined for antinociceptive activity using the hot plate and Nilsen tests. In the hot plate test (-) 3 isothujone (ED50 = 6.5 mg/kg) was found to be codeine like and equipotent with (-) Δ9 tetrahydrocannabinol while the racemic material was essentially half as potent as the levorotatory isomer. (+) 3 Thyjone was inactive in both antinociceptive tests as were several structural analogues of the 3 thujones. As with the THC's less antinociceptive activity was observed in the Nilsen test than in the hot plate assay. Acute toxicities for the 3 thujones were determined and vastly improved synthetic procedures have been developed for two long known but difficultly accessible 3 thujanols.
- Rice,Wilson
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p. 1054 - 1057
(2007/10/13)
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