- Method for synthesizing beta-damascenone
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The invention discloses a method for synthesizing beta-damascenone. The method mainly comprises the following steps: oxidizing citral through sodium chlorite; carrying out catalytic cyclization through concentrated phosphoric acid to obtain alpha-cyclogeranic acid; eliminating the alkalinity of the alpha-cyclogeranic acid under the action of thionyl chloride to obtain cyclogeranenone; carrying outaddition on the cyclogeranenone and allylmagnesium chloride and carrying out acidic isomerization to obtain alpha-damascenone; carrying out epoxidation on the alpha-damascenon through peroxyacetic acid, and carrying out alkaline ring opening through potassium carbonate; catalytically heating and dehydrating through para-toluenesulfonic acid to obtain the beta-damascenone. The method disclosed bythe invention has the advantages that raw materials are cheap and easy to obtain, reaction conditions are moderate and the operation is simple and convenient; another useful spice alpha-damascenone can be synchronously synthesized and the method is a method which is suitable for industrial production of the beta-damascenone.
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Paragraph 0048; 0051; 0052
(2019/01/14)
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- Total synthesis of viridicatumtoxin B and analogues thereof: Strategy evolution, structural revision, and biological evaluation
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The details of the total synthesis of viridicatumtoxin B (1) are described. Initial synthetic strategies toward this intriguing tetracycline antibiotic resulted in the development of key alkylation and Lewis acid-mediated spirocyclization reactions to form the hindered EF spirojunction, as well as Michael-Dieckmann reactions to set the A and C rings. The use of an aromatic A-ring substrate, however, was found to be unsuitable for the introduction of the requisite hydroxyl groups at carbons 4a and 12a. Applying these previous tactics, we developed stepwise approaches to oxidize carbons 12a and 4a based on enol- and enolate-based oxidations, respectively, the latter of which was accomplished after systematic investigations that revealed critical reactivity patterns. The herein described synthetic strategy resulted in the total synthesis of viridicatumtoxin B (1), which, in turn, formed the basis for the revision of its originally assigned structure. The developed chemistry facilitated the synthesis of a series of viridicatumtoxin analogues, which were evaluated against Gram-positive and Gram-negative bacterial strains, including drug-resistant pathogens, revealing the first structure-activity relationships within this structural type.
- Nicolaou,Hale, Christopher R. H.,Nilewski, Christian,Ioannidou, Heraklidia A.,Elmarrouni, Abdelatif,Nilewski, Lizanne G.,Beabout, Kathryn,Wang, Tim T.,Shamoo, Yousif
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supporting information
p. 12137 - 12160
(2014/11/08)
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- Total synthesis and structural revision of viridicatumtoxin B
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Will the real viridicatumtoxin B please stand up: The total synthesis of viridicatumtoxin B resulted in its structural revision and opens the way for analogue construction and biological evaluation of this complex tetracycline-like antibiotic. The highly convergent strategy employed allows for swift construction of the entire carbocyclic framework of the molecule. Copyright
- Nicolaou,Nilewski, Christian,Hale, Christopher R. H.,Ioannidou, Heraklidia A.,Elmarrouni, Abdelatif,Koch, Lizanne G.
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supporting information
p. 8736 - 8741
(2013/09/12)
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- Synthesis of the spirochroman core of dihypoestoxide and stereochemical proposal for the natural product
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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.
- Uroos, Maliha,Hayes, Christopher J.
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scheme or table
p. 5294 - 5297
(2011/02/22)
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- Improved synthesis of methyl 3-oxo-2,6,6-trimethylcyclohex-1-ene-1- carboxylate, an A-ring intermediate for (±)strigol
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Methyl 3-oxo-2,6,6-trimethylcyclohex-1-ene-1-carboxylate was synthesised over eight steps from the starting material of citral instead of α-ionone. KMnO4, HC(OEt)3 and O2/TEMPO/CuCl were substituted for NaIO4, CH3I and pyridinium chlorochromate, respectively. Every step was simplified and gave a 48% overall yield. The procedure is suitable for large scale production.
- Qianchao,Shiqing, Pi,Xinzhi, Chen
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p. 494 - 496
(2008/09/21)
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- NOVEL CYCLOHEXENE CARBOAMIDES AND CARBOTHIOAMIDES
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A compound or a mixture of compounds comprising an aromachemical compound of the formula (I): wherein: formula (II), is formula (III), or formula (IV); R is a straight or branched chain, saturated or unsaturated hydrocarbyl group; preferably, alkyl or alkenyl, having l-8 carbon atoms; R1 is a straight or branched chain, saturated or unsaturated hydrocarbyl group; preferably, alkyl or alkenyl, having l-8 carbon atoms; x is an integer from l to 8; y is an integer from 0 to 4, and Z is 0 or S, as well as compositions, products, preparations or articles having improved aroma, fragrance or odor characteristics containing as active ingredient such compound or mixture of compounds.
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Page/Page column 10-11
(2008/06/13)
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- Isolation, synthesis, and anti-tumor activities of a novel class of podocarpic diterpenes
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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.
- Xiong, Yi,Wang, Kuiwu,Pan, Yuanjiang,Sun, Hongxiang,Tu, Jue
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p. 786 - 789
(2007/10/03)
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- Stereoselective synthesis of (-)-6,7-dehydroferruginyl methyl ether
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A stereoselective synthetic route to (-)-6,7-dehydroferruginyl methyl ether was developed from (S)-(-)-α-cyclocitral. Copyright (C) 2000 Elsevier Science Ltd.
- Gan, Yonghong,Li, Anpai,Pan, Xinfu,Chan, Albert S. C.,Yang, Teng-Kuei
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p. 781 - 787
(2007/10/03)
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- Stereoselective synthesis of (+)-ferruginyl methyl ether and (+)-sugiyl methyl ether
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A facile stereoselective synthetic procedure to (+)-ferruginyl methyl ether and (+)-sugiyl methyl ether has been developed with high stereoselectivity and overall yield.
- Yonghong, Gan,Xinfu, Pan
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p. 130 - 132
(2007/10/03)
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- HETEROCUMULENES IN ACYLATION REACTIONS. 1. MECHANISM OF ACID HYDROLYSIS OF 2,6,6-TRIMETHYL-1-CARBONYLCYCLOHEX-2-ENE AND ITS THIO AND N-ISOPROPYLIMINO ANALOGS
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It was established that γ-protonation of the substrate takes place preferentially during the acid hydrolysis of 2,6,6-trimethyl-1-carbonylcyclohex-2-ene and its thio and N-isopropylimino analogs.The contribution from γ-protonation increases with increase in the polarity of the medium, the activity of H+, and the electronegativity of the heteroatom.The experimental results were confirmed by theoretical calculations (MNDO).
- Lyashchuk, S. N.,Skrypnik, Yu. G.,Bezrodnyi, B. P.
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p. 109 - 114
(2007/10/02)
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- NEW APPROACH TO THE CYCLIZATION OF TERPENOIDS
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The cyclization of pseudoionone, geranic acid, and its nitrile in the presence of catalytic amounts of acid at elevated temperature proceeds with high yield, while the corresponding cyclic products are formed predominantly as α-isomers.
- Kron, A. A.,Burdin, E. A.,Novikov, N. A.,Aul'chenko, I. S.
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p. 1901 - 1904
(2007/10/02)
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- Hydration Reactivity of Persistent Conjugated Ketenes
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The acid, neutral, and base hydrations of the crowded alkenylketene 1 and the arylketenes i-PrCPh=C=O (2) and t-BuCPh=C=O (3) have been measured, together with solvent isotope effects and general acid catalysis of the hydration of 1.The arylketenes 2 and 3 are the first for which acid-catalyzed hydration has been demonstrated.These ketenes show significantly lower reactivity than simple ketenes, and this is interpreted as the result of both steric and electronic factors operating in mechanisms involving rate-limiting proton transfer to carbon (the γ-carbon in 1) for the acid-catalyzed reaction, while both the neutral and hydroxide-induced reactions involve rate-limiting nucleophilic attack in the plane of the ketene on the carbonyl carbon.
- Allen, Annette D.,Stevenson, Andrew,Tidwell, Thomas T.
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p. 2843 - 2848
(2007/10/02)
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- Synthesis of (+/-)-trixagol by an electrophilic cyclization of an allylsilane
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1,5-Dienes containing an allylsilane are cyclized by Lewis acids to methylenecyclohexanes.The trimethylsilyl group exerts a strong activating and directing influence on the regioselectivity of this cyclization.The monocyclic compound 10 was converted into the diterpene, (+/-)-trixagol (3).
- Armstrong, Rosemary J.,Weiler, Larry
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p. 2530 - 2539
(2007/10/02)
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- Condensation of β-Cyclocitral with Benzaldehyde
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β-Cyclocitral 1b condenses with benzaldehyde in the presence of base catalysts giving the 2-benzopyrans 4, 5 and 6, and in the presence of acid catalysts giving exclusively the aldehyde 7.The cyclocitrals 1a and 1b are both isomerized by strong base anion exchange resin, but their aldehyde-protected derivatives 2 and 3 are not.Some tests used to characterize the aldehydes and their condensation products are described.
- Frank, Arlen W.
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p. 549 - 554
(2007/10/02)
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