- Syntheses of the optically active terpene hydroxyphenylselenides
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The optically active hydroxyphenylselenides derived from the p-menthane, carane, and pinane systems have been obtained. Two methods of hydroxyphenylselenides synthesis have been compared. The first method is based on the reaction of alkenes with N-(phenylseleno)succinimide in the presence of water, and the second from epoxides as a result of the reaction with sodium benzeneselenolate. The influence of the substrate structures on the composition of the obtained products has been demonstrated.
- Scianowski, Jacek,WeLniak, MirosLaw
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scheme or table
p. 1440 - 1447
(2010/03/24)
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- Syntheses and reactions of terpene β-hydroxyselenides and β-hydroxydiselenides
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A convenient method for the synthesis of optically active trans-hydroxyselenides and trans-hydroxydiselenides from the bicyclic terpene group based on the reactions of sodium selenide or sodium diselenide with cis- and trans-(+)-3-carane, trans-(+)-2-carane and (-)-β-pinane epoxides is described. The corresponding cis-hydroxy and cis-methoxydiselenides were obtained in the reaction of sodium diselenide with β-hydroxy- and β-methoxytosylates. The influence of a hydroxy group at the β-position on the diastereomeric ratio of the products of the asymmetric methoxyselenenylation of styrene has been established by composition of the products, crystal structure analyses, and theoretical calculations using a DFT method on the B3LYP level (6-311G(d)).
- Scianowski, Jacek,Rafinski, Zbigniew,Wojtczak, Andrzej,Burczynski, Krzysztof
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body text
p. 2871 - 2879
(2010/03/30)
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- Enantioselective baeyer-villiger oxidation catalyzed by palladium(II) complexes with chiral P,N-ligands
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(Chemical Equation Presented) Asymmetric Baeyer-Villiger reaction of symmetrical cyclobutanones 1a-j with urea-hydrogen peroxide (UHP) can be catalyzed by a complex of Pd(II) and the new terpene-derived P,N-ligand 7. The resulting lactones 2a-j were obtained in high yields and with good enantioselectivity (≤81% ee).
- Malkov, Andrei V.,Friscourt, Frederic,Bell, Mark,Swarbrick, Martin E.,Kocovsky, Pavel
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p. 3996 - 4003
(2008/09/20)
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- METHODS AND INTERMEDIATES FOR THE SYNTHESIS OF DELTA-9 TETRAHYDROCANNABINOL
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Processes are disclosed for the synthesis of Delta-9 tetrahydrocannabinol which result in an improved Y-THC/Y-THC ratio, and intermediates are disclosed that may be used in the synthesis of Delta-9 tetrahydrocannabinol such that improved Y-THCIY-THC ratios are achieved. The intermediates may be cyclic compounds prepared from 2-Carene. There is also provided a scaleable process for the preparation of (+)-p-menth-2-ene-1, 8-diol,, another intermediate used in the synthesis of delta-9-tetrahydrocannibinol.
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Page/Page column 3/7; 16-17
(2008/06/13)
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- The enantioselective syntheses of bisabolane sesquiterpenes Lepistirone and Cheimonophyllon E
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The synthetic approach to the bisabolane sesquiterpenes Lepistirone 1 and Cheimonophyllon E 2 involves the transformation of (+)-2-carene (5) into the p-menthane furans 8 and 11. Regio- and stereoselective alkylation, and standard reactions complete the e
- Brocksom, Timothy John,Zanotto, Paulo R.,Brocksom, Ursula
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p. 2397 - 2398
(2007/10/03)
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- Synthesis of new chiral 2,2′-bipyridine ligands and their application in Copper-catalyzed asymmetric allylic oxidation and cyclopropanation
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A series of modular bipyridine-type ligands 1 and 3-9 has been synthesized via a de novo construction of the pyridine nucleus. The chiral moieties of these ligands originate from the isoprenoid chiral pool, namely, β-pinene (10 → 1), 3-carene (14 → 3 and 5), 2-carene (28 → 4), α-pinene (43 → 6-8), and dehydropregnenolone acetate (48 → 9), respectively. Copper(I) complexes, derived from these ligands and (TfO)2Cu (1 mol%) upon an in situ reduction with phenylhydrazine, exhibit good enantioselectivity (up to 82% ee) and unusually high reaction rate (typicaly 30 min at room temperature) in allylic oxidation of cyclic olefins (52 → 53). Copper-catalyzed cyclopropanation proceeded with ≤76% enantioselectivity and ~3:1 to 99:1 trans/cis-diastereoselectivity (54 → 55 + 56). The level of the asymmetric induction is discussed in terms of the ligand architecture that controls the stereochemical environment of the coordinated metal.
- Malkov, Andrei V.,Pernazza, Daniele,Bell, Mark,Bella, Marco,Massa, Antonio,Teply, Filip,Meghani, Premji,Kocovsky, Pavel
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p. 4727 - 4742
(2007/10/03)
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- Substrate-induced diastereoselectivity in the dimethyldioxirane epoxidation of simple alkenes and dienes
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Various alkenes and dienes, such as (R)- or (S)-limonene 2, 2-carene 6, 3-carene 8, (R)-α-pinene 10, (S)-α-pinene 12, and endo-dicyclopentadiene 14 were transformed into the corresponding mono- and bis-epoxides by epoxidation with dimethyldioxirane (as an acetone solution). The selectivity observed in these epoxidations is explained by the assumption of hydrogen bonding between bridge protons and the dioxirane.
- Asouti,Hadjiarapoglou
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p. 1847 - 1850
(2007/10/03)
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- Modular pyridine-type P,N-ligands derived from monoterpenes: Application in asymmetric Heck addition
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Novel (diphenylphosphinophenyl)pyridine ligands (+)-8, (+)-15, (-)-21, and (-)-26 were synthesized from (-)-β-pinene, (+)-3-carene, (+)-2-carene, and (-)-α-pinene, respectively, via Kro?hnke annulation as the key step, and shown to effect ≤88% ee in Heck addition (27→28). Ligands (+)-15 and (-)-21 are quasi-enantiomeric; ligands 8 and 26 can be prepared in both enantiomeric forms from (+)- and (-)-enantiomers of α- and β-pinene, respectively.
- Malkov, Andrei V.,Bella, Marco,Stará, Irena G.,Ko?ovsky, Pavel
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p. 3045 - 3048
(2007/10/03)
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- Acid-catalysed Terpenylations of Olivetol in the Synthesis of Cannabinoids
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Examination of the toluene-p-sulphonic acid-catalysed reaction of (1S,2S,3R,6R)-(+)-trans-car-2-ene epoxide with olivetol shows that, inconsistently with the accepted mechanism, (3R,4R)-(-)-o- and -p-cannabidiols are produced as well as (3R,4R)-(-)-Δ1- and Δ6-tetrahydrocannabinols.Evidence is now presented that, as in Petrzilka's reaction employing chiral p-mentha-2,8-dien-1-ols, the reacting species is the delocalised (4R)-p-mentha-2,8-dien-1-yl cation (9).Similar terpenylation using (1S,3S,4R,6R)-(+)-trans-car-3-ene epoxide shows that besides the reported (-)-Δ6-THC, o- and p-cannabidiols, Δ1-THC and Δ4,8-iso-THC can also be produced.The nature of the products, the chirality, and the characteristics of the reaction implicate again the delocalised cation (9).Its formation via Kropp-type rearrangement is excluded and a pathway leading to (4R)-p-mentha-2,6,8-triene, which on protonation gives (9), is proposed.Protonated on C-8, the triene can be trapped and isolated as (4R)-p-mentha-2,6-dien-8-ol.The latter, made in (+/-)-form from citral, proved to be an excellent terpenylating agent for producing cannabinoids.Terpenylation of olivetol by the pinanes (1S,4S,5S)-(-)-cis-verbenol and (1R,5S,7R)-(+)-cis-chrysanthenol is compared.A major drawback of the latter is partial racemisation which occurs in the verbenone-chrysanthenone isomerisation during its photochemical preparation.Whilst Δ1-THC cannot be directly obtained from verbenol, its tertiary allylic cation permits a much higher yielding terpenylation than the secondary cation from chrysanthenol.
- Crombie, Leslie,Crombie, W. Mary L.,Jamieson, Sally V.,Palmer, Christopher J.
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p. 1243 - 1250
(2007/10/02)
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