6627-74-3Relevant articles and documents
Enantioselective enzymatic resolution of racemic alcohols by lipases in green organic solvents
Belafriekh, Abderahmane,Secundo, Francesco,Serra, Stefano,Djeghaba, Zeineddine
, p. 473 - 478 (2017/03/23)
The effects of two eco-friendly solvents, 2-methyltetrahydrofuran (MeTHF) and cyclopentyl methyl ether (CPME), on the enzyme activity and enantioselectivity of Novozym 435, Candida rugosa lipase (CRL), Porcine pancreas lipase (PPL), Lipase AK, Lipase PS, and Lipozyme, a series of commercial lipases, in the enantioselective transesterfications of racemic menthol, racemic sulcatol and racemic α-cyclogeraniol were studied. Vinyl acetate was chosen as the acyl donor and the reactions were carried out at water activity 0.06. The activity of lipases in CPME was similar to that observed in other largely employed organic solvents [toluene and tert-butyl methyl ether (MTBE)], and was slightly lower in MeTHF. However, for most of the lipases tested, the enantioselectivity was higher in the eco-friendly solvents. Lipase AK exhibited a high enantioselectivity (E?=?232) for the resolution of racemic menthol but the reaction rate was low. Lipase formulation (the enzyme was frozen and lyophilized in potassium phosphate buffer without and with 5% (w/v) of sucrose, D-mannitol, or methoxy poly(ethylene glycol)) was tested with this lipase in order to improve its activity, which increased up to 4.5 times, compared to the untreated enzyme. CALB was found to be a useful biocatalyst for the resolution of racemic sulcatol, where high activity and enantioselectivity were obtained (E?≥?1000). For the resolution of the racemic primary alcohol α-cyclogeraniol, most of the lipases tested were active but not enantioselective, except lipase PS which displayed a moderate enantioselectivity (E?=?19). The effect of the presence of a low percentage of two ionic liquids (ILs) 1-Butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([BMIM][TFSI]) (5% (v/v)) and 1-Butyl-3-methylimidazoliumtetrafluoroborate ([BMIM][BF4]) (1% (v/v)) in the medium was also investigated. Only in the case of CRL the ILs slightly increased the enantioselectivity from E?=?91 to E?=?103 and E?=?120 for [BMIM][TFSI] and [BMIM][BF4], respectively. However, in all cases ILs caused a decrease of enzyme activity.
Synthesis of the spirochroman core of dihypoestoxide and stereochemical proposal for the natural product
Uroos, Maliha,Hayes, Christopher J.
supporting information; experimental part, p. 5294 - 5297 (2011/02/22)
The tricyclic spirochroman core of dihypoestoxide has been synthesized from geranoic acid in seven steps using a hetero-Diels-Alder cycloaddition as a key step, thus providing support for the proposed biosynthesis of the natural product. Furthermore, analysis of the 13C NMR data obtained for all four diastereoisomers of the synthetic spirochroman core has allowed us to propose a full stereochemical assignment for dihypoestoxide.
Lipase-mediated resolution of the hydroxy-cyclogeraniol isomers: application to the synthesis of the enantiomers of karahana lactone, karahana ether, crocusatin C and γ-cyclogeraniol
Serra, Stefano,Gatti, Francesco G.,Fuganti, Claudio
experimental part, p. 1319 - 1329 (2009/12/01)
A comprehensive study on the lipase PS-mediated resolution of different hydroxy-geraniol isomers is reported. A number of α-, β- and γ-isomers bearing a 2-, 3- or 4-hydroxy functional group were synthesised regioselectively and then submitted to the lipase-mediated kinetic acetylation. The latter experiments showed that the 2-hydroxy isomers 4, 5 and 14 (α, γ and β, respectively) as well as cis-3-hydroxy α-cyclogeraniol 7 and cis-4-hydroxy γ-cyclogeraniol 10 could be easily resolved by this procedure. The enantiomeric purity of the main part of these compounds was increased by recrystallisation and the enantiopure diols obtained were used as building blocks for the synthesis of the natural terpenoids karahana lactone, karahana ether and crocusatin C and for the preparation of the synthetic intermediate γ-cyclogeraniol. The absolute configurations of the enantiomers of the diols 7, 10, 14 and 19 were determined by chemical correlation with the known compounds 40, 41, 39 and 41, respectively.
Isolation, synthesis, and anti-tumor activities of a novel class of podocarpic diterpenes
Xiong, Yi,Wang, Kuiwu,Pan, Yuanjiang,Sun, Hongxiang,Tu, Jue
, p. 786 - 789 (2007/10/03)
A novel unusual 17-carbon diterpenoid, named (+)-7-deoxynimbidiol, was isolated from the stalks of Celastrus hypoleucus (Oliv.) Warb. Its racemate and derivatives were synthesized, and the inhibitory activities of these compounds against four cultured human-tumor cell lines were evaluated. The structure-activity relationship was discussed.
Y-zeolite-catalyzed cyclizations of terpenols
Yu, Wei,Bian, Fengling,Gao, Yuan,Yang, Li,Liu, Zhong-Li
, p. 59 - 62 (2007/10/03)
Depending on the metal doped and the activation temperature, Y-zeolites can catalyze a diversity of reactions of geraniol (1), linalool (2) and nerol (3). Compound 1 can be transformed to α- and/or γ-cyclogeraniol (4 and 5) highly efficiently.
Biomimetic cyclization of small terpenoids promoted by zeolite NaY: Tandem formation of α-ambrinol from geranyl acetone
Tsangarakis, Constantinos,Stratakis, Manolis
, p. 1280 - 1284 (2007/10/03)
Zeolite NaY promotes efficiently the biomimetic cyclization of small acyclic terpenes. Geranyl and neryl acetone undergo a novel tandem 1,5-diene cyclization/carbonyl-ene reaction to form the natural product α-ambrinol isolated in >65% yield.
Superacidic cyclisation-lipase-mediated kinetic resolution as a short route from achiral linear isoprenoid alcohols to scalemic cyclic isomers
Serebryakov, Edward P.,Gamalevich, Galina D.,Kulcitki, Veacheslav N.,Ungur, Nicon D.,Vlad, Pavel F.
, p. 59 - 60 (2007/10/03)
(±)-α-Cyclogeraniol and (±)-drim-7-en-11-ol acetates obtained via the FSO3H-induced cyclisation of geraniol and (E)-farnesol and subsequent acetylation were hydrolysed in the presence of hog pancreas lipase (PPL) to afford (R)-(+)-α-cyclogeraniol (ee ～30% at the optimal conversion C = 20±2%) and (5R,9R,10R)-(+)-drim-7-en-11-ol (ee 78.5% at C = 30%), respectively; (±)-15-acetoxyisoagath-12-ene, obtained similarly from all-E-geranylgeraniol, is resistant to PPL-mediated hydrolysis, but is hydrolysed in the presence of lipase from Candida cylindracea to afford (10S,14R)-(-)-isoagath-12-en-15-ol of 69-80% ee in ～3% yield.
Model insect antifeedants. Synthesis of azadiradione fragments through acyl radicals cyclizations and stannane coupling reactions
Fernandez-Mateos, Alfonso,Coca, Gustavo Pascual,Gonzalez, Rosa Rubio,Hernandez, Carolina Tapia
, p. 4817 - 4828 (2007/10/03)
A diastereoselective and versatile synthesis of the model insect antifeedant 16 related to azadiradione has been achieved in nine steps starting from α-cyclocitral 1. The key steps involve intramolecular alkene addition of an acyl radical and a Stille coupling reaction of a vinyl iodide with a stannylfuran.
Limonoid model insect antifeedants. A stereoselective synthesis of azadiradione C, D, and E fragments through intramolecular diazo ketone cyclization
Fernandez Mateos,Lopez Barba
, p. 3580 - 3585 (2007/10/02)
A stereoselective synthesis of model compound 18 of the insect antifeedant azadiradione has been accomplished starting from α-cyclocitral in 12 steps in 15% overall yield. The strategy for the synthesis is based on an intramolecular cyclopropanation of a diazo ketone and subsequent selective cleavage of a cyclopropyl ketone. Reactivity differences in the cleavage of the key cyclopropyl ketone 13 and its homolog 12 lacking the furyl ring are explored.
Superacidic low-temperature cyclization of terpenols and their acetates
Vlad, P. F.,Ungur, N. D.,Nguen Van Hung,Perutsky, V. B.
, p. 2391 - 2403 (2007/10/03)
The superacidic low-temperature cyclization of terpenols and their acetates be fluorosulfonic acid represents a highly efficient chemo- and structurally selective and stereospecific process.Homoallylic alcohols (α-isomers of cycloterpenols) are the products of cyclization of terpenols; the configuration of the hydroxymethyl group in the products is predetermined by the configuration of the allylic double bond in aliphatic or partially cyclized precursors.The cyclization of terpenyl acetates yields monoacetates of fully cyclized diastereomeric primary-tertiary γ-diols.Their stereochemistry also depends on the configuration of the allylic double bond in the starting substrates. - Key words: terpenols; terpenyl acetates; cyclization, fluorosulfonic acid, drimanes, isoagathanes, scarlanes.
