- Eleuthesides and their analogs: VII. Synthesis of menthane derivatives by the Diels-Alder reaction of levoglucosenone with (2E,4E)-hexa-2,4-dien-1-yl acetate
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The Diels-Alder reaction of levoglucosenone with (2E,4E)-hexa-2,4-dien-1-yl acetate was used to synthesize chiral functionalized derivatives of isopropyl(methyl)cyclohexene fused to a carbohydrate fragment.
- Pilipenko,Sharipov,Valeev
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Read Online
- Catalytic Asymmetric Allylic Substitution with Copper(I) Homoenolates Generated from Cyclopropanols
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By using copper(I) homoenolates as nucleophiles, which are generated through the ring-opening of 1-substituted cyclopropane-1-ols, a catalytic asymmetric allylic substitution with allyl phosphates is achieved in high to excellent yields with high enantioselectivity. Both 1-substituted cyclopropane-1-ols and allylic phosphates enjoy broad substrate scopes. Remarkably, various functional groups, such as ether, ester, tosylate, imide, alcohol, nitro, and carbamate are well tolerated. Moreover, the present method is nicely extended to the asymmetric construction of quaternary carbon centers. Some control experiments argue against a radical-based reaction mechanism and a catalytic cycle based on a two-electron process is proposed. Finally, the synthetic utilities of the product are showcased by means of the transformations of the terminal olefin group and the ketone group.
- Shi, Chang-Yun,Yin, Liang,Zhang, Qi,Zhou, Si-Wei
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supporting information
p. 26351 - 26356
(2021/11/09)
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- Step-Economic Synthesis of Biomimetic β-Ketopolyene Thioesters and Demonstration of Their Usefulness in Enzymatic Biosynthesis Studies
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Studies on the biosynthetic processing of polyene thioester intermediates are complicated by limited access to appropriate substrate surrogates. We present a step-economic synthetic access to biomimetic β-ketopolyene thioesters that is based on an Ir-catalyzed reductive Horner-Wadsworth-Emmons olefination. New β-ketotriene and pentaenethioates of pantetheine and N-acetylcysteamine were exemplarily synthesized via short and concise routes. The usefulness of these compounds was demonstrated in an in vitro assay with the ketoreductase domain MycKRB from mycolactone biosynthesis.
- Hahn, Frank,Ro?, Theresa,Schr?der, Marius,Wunderlich, Johannes
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supporting information
(2020/07/04)
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- Synthesis method of laspeyresia pomonella sex pheromone
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The invention relates to a synthesis method of laspeyresi pomonella sex pheromone. The method comprises the steps as follows: (1) methanol is added to methyl sorbate as a raw material, and an intermediate A sorbic alcohol is obtained through 5% palladium-carbon catalytic hydrogenation reduction; (2) the intermediate A sorbitol obtained in (1) and acetic anhydride are subjected to a reaction in ethyl acetate, triethylamine and water to obtain an intermediate B sorbic acetate; (3) 6-chlorohexanol is subjected to a reaction with trimethylchlorosilane in toluene in the presence of ethyl acetate and triethylamine, after the reaction, water is added, stirring and layering are performed, and an intermediate C6-chlorohexanol trimethylsilyl ester is obtained; (4) the intermediate B sorbic acetate and the intermediate C6-chlorohexanol trimethylsilyl ester are subjected to a reaction with sodium sand in a toluene solution, then, water and sulfuric acid are dropwise added, layering and rectification are performed, and a target product E8,E10-dodecadiene-1-ol is obtained. The synthesis method has the advantages as follows: the laspeyresi pomonella sex pheromone is synthesized from available rawmaterials, the reaction route is short, and the selectivity and product yield can be increased.
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Paragraph 0030-0032; 0039-0041
(2019/09/17)
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- One Stone for Three Birds-Rhodium-Catalyzed Highly Diastereoselective Intramolecular [4+2] Cycloaddition of Optically Active Allene-1,3-dienes
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RhCl(PPh3)3-catalyzed [4+2] intramolecular cycloaddition of optically active axially chiral allene-dienes afforded cis-fused [3.4.0]-bicyclic products with three chiral centers in good yields with an excellent chemo- and diastereoselectivity. A pair of enantiomers of such products was generated highly selectively from both enantiomers of starting allene-dienes, indicating that the axial chirality dictated the absolute configurations of the three in situ generated chiral centers with a very high efficiency of chirality transfer.
- Han, Yulin,Qin, Anni,Ma, Shengming
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p. 486 - 496
(2019/04/04)
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- Biocatalysed reduction of carboxylic acids to primary alcohols in aqueous medium: A novel synthetic capability of the zygomycete fungus Syncephalastrum racemosum
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Abstract The zygomycete fungus Syncephalastrum racemosum shows the remarkable capability of reducing carboxylic acids to primary alcohols in water medium, at ambient temperature and pressure. The reaction does not require molecular hydrogen, and in most cases affords quantitative transformations. The results herein reported highlight the basic molecular scaffold that can be accepted by the fungus, the effects due to substituents, and also the possibility that carboxylic acids can be generated in the reaction medium by enzymatic hydrolysis of the corresponding methyl esters. This biocatalysed reduction implements the scarcely supplied enzymatic toolbox for the conversion of carboxylic groups into primary alcohols, which can be exploited for the optimisation of sustainable synthetic procedures.
- Brenna, Elisabetta,Cannavale, Flavia,Crotti, Michele,Parmeggiani, Fabio,Romagnolo, Alice,Spina, Federica,Varese, Giovanna Cristina
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- SYNTHESIS OF OLEFINIC ALCOHOLS VIA ENZYMATIC TERMINAL HYDROXYLATION
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In certain aspects, the present invention provides methods for producing terminally hydroxylated alkenes and alkynes by contacting an unsaturated or saturated hydrocarbon substrate with a hydroxylase enzyme. Exemplary terminal hydroxylases useful for carrying out the methods of the invention exhibit strong selectivity towards one terminal carbon of a hydrocarbon substrate and include, but are not limited to, non-heme diiron alkane monooxygenases, cytochromes P450 (e.g., cytochromes P450 of the CYP52 and CYP153 family), as well as long chain alkane hydroxylases. In some embodiments, the terminally hydroxylated alkene or alkyne is further converted to a terminal alkenal. In certain embodiments, terminally hydroxylated alkenes and alkynes are useful as insect pheromones which modify insect behavior. In other embodiments, terminally hydroxylated alkenes and alkynes are useful intermediates for producing pheromones via acetylation or oxidation of the alcohol moiety.
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Paragraph 0314; 0315
(2016/01/30)
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- Z-Stereoselective semi-reduction of alkynes: Modification of the Boland protocol
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Highly Z-selective semi-reduction of alkynes has been achieved by adding TMSCl to a mixture of Zn(Cu/Ag), water, and methanol. The conjugated Z-alkenes have been prepared in high yields at ambient temperature. The formation of isomeric E-alkenes and over-reduction to alkanes were suppressed in our modified Boland reduction protocol. The methodology was extended to the preparation of Z-substituted stilbenes.
- Mohamed, Yasser M.A.,Hansen, Trond Vidar
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p. 3872 - 3877
(2013/06/27)
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- Reduction of carboxylic acids using esters of benzotriazole as high-reactivity intermediates
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Herein, we describe a simple and practical protocol for the reduction of carboxylic acids via the in situ formation of hydroxybenzotriazole esters followed by reaction with sodium borohydride to give the corresponding alcohols. The reaction proceeds with excellent yields in the presence of water. Georg Thieme Verlag Stuttgart - New York.
- Morales-Serna, Jose Antonio,Garcia-Rios, Erendira,Bernal, Jorge,Paleo, Ehecatl,Gavino, Ruben,Cardenas, Jorge
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scheme or table
p. 1375 - 1382
(2011/06/19)
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- Supramolecular catalyst for aldehyde hydrogenation and tandem hydroformylation-hydrogenation
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The chemoselective reduction of aldehydes and the tandem hydroformylation-hydrogenation of terminal alkenes are possible with a supramolecular catalyst that operates by a novel mechanism involving substrate activation by hydrogen bonding and subsequent metalligand bifunctional hydrogenation (see scheme).
- Diab, Lisa,Smejkal, Tomas,Geier, Jens,Breit, Bernhard
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supporting information; experimental part
p. 8022 - 8026
(2010/02/28)
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- Direct conversion of polyconjugated compounds into their corresponding carboxylic acids by Acetobacter aceti
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The conversion of polyconjugated aldehydes or alcohols into their corresponding acids was carried out using Acetobacter aceti. The analytical results were compared with those of the acids chemically obtained using a Horner-Wittig reaction.
- Pini, Elena,Bertacche, Vittorio,Molinari, Francesco,Romano, Diego,Gandolfi, Raffaella
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p. 8638 - 8641
(2008/12/21)
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- Iridium-catalyzed intermolecular allylic etherification with aliphatic alkoxides: Asymmetric synthesis of dihydropyrans and dihydrofurans
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Hindered chiral ethers with one or two stereocenters are now readily available by allylic etherification of primary and secondary alkoxides (see reaction). When an Ir-phosphoramidite complex is used as the catalyst, the reaction proceeds with high regio-, enantio-, and diastereoselectivity. Np = 1-naphthyl.
- Shu, Chutian,Hartwig, John F.
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p. 4794 - 4797
(2007/10/03)
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- Efficient intramolecular Diels-Alder reactions of ester-tethered 1,7,9-decatrienoates catalyzed by bis-aluminated trifluoromethanesulfonamide
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Bis-aluminated trifluoromethanesulfonamide generated in situ by mixing TfNH2 (1 mol) and methylaluminum reagent (2 mol) is an effective catalyst for the IMDA reaction of ester-tethered 1,7,9-decatrienoates. Graphical Abstract
- Saito, Akio,Yanai, Hikaru,Taguchi, Takeo
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p. 12239 - 12247
(2007/10/03)
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- POLYUNSATURATED LINEAR ALDEHYDES AND THEIR DERIVATIVES WITH ANTI-RADICAL AND ANTI-TUMORAL ACTIVITY
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The invention relates to polyunsaturated linear aldehydes and derivatives thereof which can be extracted from the feathers or tissues of parrots of prepared synthetically with antioxidant, antitumoral and anti-inflammatory activity, and which are useful in the prevention and treatment of cardiovascular, inflammatory, atherosclerotic, proliferative cell and tumour damage and the prevention of alterations caused by ageing.
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Page/Page column 7
(2008/06/13)
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- Pentadienyl type lithium and potassium species: The regioselectivity of their reactions with electrophiles
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Seven structurally distinct pentadienyl type lithium and potassium compounds were screened against a variety of electrophiles in order to assess the regioselectivity of the trapping reactions. Organoborates and analogs thereof (fluorodimethoxyborane) proved to be perfectly regioreliable attacking only unsubstituted terminal positions and thus providing, after oxidation, exclusively primary allylic alcohols. 2,4-Pentadienyllithiums or -potassiums, that carry a methyl group at the 1- or 3-position, exhibit the same extreme regioselectivity towards halotrialkylsilanes or carbon dioxide. Although the unsubstituted parent compounds combine with such electrophiles still preferentially at the terminal position, considerable proportions of branched products are concomitantly formed as well (1/3-attack ratios ranging from 2:1 to >20:1). Hydroxyalkylating and alkylating reagents such as formaldehyde, oxirane or butyl iodide invariably afford regioisomeric mixtures generally varying in composition between 3:1 and 1:3. The condensation reaction with halotrialkylsilanes appears to follow a concerted (SN2-like) rather than an addition/elimination (ate complex-mediated) mechanism.
- Schlosser,Zellner,Leroux
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p. 1830 - 1836
(2007/10/03)
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- A short synthesis of conjugated unsaturated alcohols
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Isomerization of acetylenic pentafluorophenyl esters in the presence of phosphines gives rise to activated dienoic esters, which can be reduced directly in a simple one pot procedure to the corresponding conjugated unsaturated alcohols 6-10. The higher reactivity of the pentafluorophenyl esters in comparison to alkyl esters allows their selective isomerization.
- Kazmaier, Uli
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p. 1491 - 1496
(2007/10/03)
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- Asymmetric synthesis of bicyclopropane derivatives
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Both syn- and anti-bicyclopropane derivatives have been efficiently prepared with good relative and absolute stereocontrol using reagent controlled asymmetric cyclopropanation reactions. Double Simmons-Smith cyclopropanation of 2,4-dien-1-ols stereoselectively gave the corresponding anti-bicyclopropane derivatives.
- Barrett, Anthony G. M.,Doubleday, Wendel W.,Tustin, Gary J.
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p. 15325 - 15338
(2007/10/03)
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- A novel strategy for regio- and stereocontrol in [4 + 2] cycloadditions. Intramolecular Diels-Alder reaction of a sllyl acetal triene
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The synthesis of the novel silyl acetal-containing triene 1 is described. Triene 1 underwent regiospecific and highly stereo selective intramolecular Diels-Alder reaction to give bicycle 5. Acidic methanolysis of 5 gave hydroxylactone 2, whose structure was established by X-ray crystallography.
- Craig, Donald,Reader, John C.
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p. 6585 - 6588
(2007/10/02)
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- Method for preparing an aldehyde or alcohol by reduction of a carboxylic acid
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The inventive method is particularly advantageous for the preparation of an unsaturated alcohol or aldehyde by the reduction of a corresponding unsaturated carboxylic acid since the unsaturated double bond in the starting acid is not hydrogenated by the reaction of reduction. The method comprises first reacting the starting acid with an alkyl chloroformate to form an intermediate compound by the dehydrochlorination and the intermediate compound is then reduced by using sodium borohydride as the reducing agent. The proportion of the aldehyde to alcohol in the product mixture can be controlled by modifying the amount of the reducing agent and/or the reaction time.
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- An Approach to Cytochalasan Synthesis: Macrolide Formation by an Intramolecular Diels-Alder Reaction. X-Ray Structure of Methyl (1RS, 2SR, 5RS, 6RS)-2,5-Dimethyl-1-hydroxy-6-cyclohex-3-ene-1-carboxylate
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When heated in toluene under reflux, under high dilution conditions, trans,trans-hexadeca-12,14-dienoyl-oxymaleic anhydride (4) cyclised via an intramolecular Diels-Alder reaction to give the macrocyclic lactone (5) in 27percent yield together with 5percent of a regioisomer (23). (1RS, 2SR, 5RS, 6RS)-2,5-Dimethyl-1-octanoyloxycyclohex-3-ene-1,6-dicarboxylic acid anhydride (11) was converted into the methyl (1RS, 2SR, 5RS, 6RS)-2,5-dimethyl-1-octanoyloxy-6-benzylcarbonylcyclohex-3-ene-1-carboxylate (33), but selective reduction of this ketone was unsuccessful.The structure of one of the reduction products, methyl (1RS, 2SR, 5RS, 6RS)-2,5-dimethyl-1-hydroxy-6-cyclohex-3-ene-1-carboxylate (35) was confirmed by an X-ray structure determination.
- Bailey, Stephen J.,Thomas, Eric J.,Vather, Sunil M.,Wallis, John
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p. 851 - 860
(2007/10/02)
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- Selectivity in Allylic Substitution with Organometallics through Neighbouring Co-ordination. Part 2. Reactions of 2-Allylthiobenzothiazoles with Organocopper Reagents
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Efficient control of the regioselectivity in allylic substitutions with Grignard reagents in the presence of copper(I) bromide has been achieved by using 2-allylthiobenzothiazoles as electriphiles.The SN2:SN2' product ratio depends on the degree of co-ordination between the allylic reagent and the organometalic species.
- Calo, Vincenzo,Lopez Luigi,Carlucci, Walter
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p. 2953 - 2956
(2007/10/02)
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- Novel Synthesis of (Z)-3-Hexen-1-ol and cis-Jasmone
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Both (Z)-3-hexen-1-ol and cis-jasmone were synthesised via 1,4-selective hydrogenation of conjugated dienes in the presence of arene Cr(CO)3 or Cr(CO)6 catalysts as the key step.
- Furuhata, Akimichi,Onishi, Ken,Fujita, Akira,Kogami, Kunio
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p. 1757 - 1760
(2007/10/02)
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- Dienyl methacrylates
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Compound of the formula CH2 =C(CH3)CO2 R wherein R is an alkadienyl or cycloalkadienyl group which contains the 1,3- or 1,4-diene carbon skeleton, homopolymers and copolymers of the compound, and curable finishes containing the homopolymer and/or copolymer.
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