52646-93-2Relevant articles and documents
A general strategy for the stereoselective synthesis of the furanosesquiterpenes structurally related to pallescensins 1-2
Serra, Stefano
, (2019/05/24)
Here, we describe a general stereoselective synthesis of the marine furanosesquiterpenes structurally related to pallescensins 1-2. The stereoisomeric forms of the pallescensin 1, pallescensin 2, and dihydropallescensin 2 were obtained in high chemical and isomeric purity, whereas isomicrocionin-3 was synthesized for the first time. The sesquiterpene framework was built up by means of the coupling of the C10 cyclogeranyl moiety with the C5 3-(methylene)furan moiety. The key steps of our synthetic procedure are the stereoselective synthesis of four cyclogeraniol isomers, their conversion into the corresponding cyclogeranylsulfonylbenzene derivatives, their alkylation with 3-(chloromethyl)furan, and the final reductive cleavage of the phenylsulfonyl functional group to afford the whole sesquiterpene framework. The enantioselective synthesis of the α-, 3,4-dehydro-γ- and γ-cyclogeraniol isomers was performed using both a lipase-mediated resolution procedure and different regioselective chemical transformations.
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.
A simple and efficient highly enantioselective synthesis of α-ionone and α-damascone
Bovolenta, Marcella,Castronovo, Francesca,Vadala, Alessandro,Zanoni, Giuseppe,Vidari, Giovanni
, p. 8959 - 8962 (2007/10/03)
An efficient highly enantioselective (ee ≥99%) synthesis of α-ionone and α-damascone is described. Both enantiomers of title compounds were synthesized through two straightforward pathways diverging from enantiopure (R)- or (S)-α-cyclogeraniol. These versatile building blocks were obtained by regioselective ZrCl4-promoted biomimetic cyclization of (6S)- or (6E)-(Z)-6,7-epoxygeraniol, respectively, followed by deoxygenation of the so formed secondary alcohol. The chiral information was encoded by a highly regioselecive Sharpless asymmetric dihydroxylation of inexpensive geranyl acetate.
Stereoselective synthesis of (+)-ferruginyl methyl ether and (+)-sugiyl methyl ether
Yonghong, Gan,Xinfu, Pan
, p. 130 - 132 (2007/10/03)
A facile stereoselective synthetic procedure to (+)-ferruginyl methyl ether and (+)-sugiyl methyl ether has been developed with high stereoselectivity and overall yield.
Stereoselective synthesis of (-)-6,7-dehydroferruginyl methyl ether
Gan, Yonghong,Li, Anpai,Pan, Xinfu,Chan, Albert S. C.,Yang, Teng-Kuei
, p. 781 - 787 (2007/10/03)
A stereoselective synthetic route to (-)-6,7-dehydroferruginyl methyl ether was developed from (S)-(-)-α-cyclocitral. Copyright (C) 2000 Elsevier Science Ltd.
153. Synthese von optisch aktiven, natuerlichen Carotinoiden und strukturell verwandten Naturprodukten. IV. Synthese von (3R,3'R,6'R)-Lutein
Mayer, Hans,Ruettimann, August
, p. 1451 - 1455 (2007/10/02)
The synthesis of (3R,3'R,6'R)-lutein (19) according to the building principle C25+C15=C40 is reported utilizing (R)-4-hydroxy-2,6,6-trimethyl-2-cyclohexen-1-one (4) as a readily available key intermediate.
