- Synthesis of Pyranocyclopentaindolines Representing the Western Sections of Janthitrem B, JBIR-137, and Shearinine G
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The synthesis of the ABCD tetracyclic partial structures of the fungal indole diterpenes janthitrem B, JBIR-137, and shearinine G is reported. The route starts from 5-formylated indoline that is coupled to a dihydropyran moiety, followed by Prins cyclization. A diene was obtained that was oxygenated in a divergent manner. The hydroxylated tetracyclic western half of janthitrem B was obtained in eight steps and 10 % overall yield. We also share our experience with alternative approaches passing via alkynylated precursors. This includes the gold-catalyzed cycloisomerization of a 6-ethynyl-5-prenylindoline.
- Fresia, Marvin,Lindel, Thomas
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supporting information
(2022/02/05)
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- In-situ IR Spectroscopy Study of Reactions of C3 Oxygenates on Heteroatom (Sn, Mo, and W) doped BEA Zeolites and the Effect of Co-adsorbed Water
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The reactions of acetone and hydroxyacetone over heteroatom doped BEA zeolites (Sn, Mo, and W) in the presence and absence of H2O vapor are investigated using infrared spectroscopy. Acetone is converted to mesityl oxide over Sn-BEA exclusively. At higher temperatures, larger oxygenates such as phorones, aromatics, and coke form. The presence of co-adsorbed water in Sn-BEA suppresses tautomerization. H2O vapor is also beneficial for minimizing coke formation at high temperatures. Hydroxyacetone is converted into 2-hydroxypropanal over Sn-BEA, exhibiting high affinity to Sn sites up to 400 °C. Sn-BEA catalyzes conversion of hydroxyacetone into the enol in the absence of H2O, but exposure to H2O induces the formation of 2-hydroxypropanal and subsequent conversion to acrolein. The Lewis acid descriptors are used to rationalize the reaction pathways. For the isomerization of hydroxyacetone into 2-hydroxypropanal, the hardness of acid sites influences the reaction and correlates with the overall Lewis acidity of the catalysts, respectively. However, the size of the exchanged metal significantly affects aldol condensation, where keto and enol forms of acetone adsorb to active sites simultaneously.
- Najmi, Sean,So, Jungseob,Stavitski, Eli,McDermott, William P.,Lyu, Yimeng,Burt, Sam P.,Hermans, Ive,Sholl, David S.,Sievers, Carsten
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p. 445 - 458
(2020/12/01)
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- Improved synthesis method of isophorone
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The improved isophorone synthesis method comprises the following steps: selecting 2, 2, 6 and 6 - tetramethyl -4 - piperidone to prepare 1 -nitroso 2, 2, 6 and 6 - tetramethyl -4 - piperidone in a market. The large-site alkali-resistant catalyst is potassium isopropoxide. Any one of sodium isopropoxide, potassium tert-butoxide, sodium tert-butoxide, potassium n-butoxide, sodium n-butoxide, potassium isobutanol, sodium isobutanol, potassium n-pentanol, and sodium isoamyl alcohol. To the method, by adopting a large sterically hindered base as a catalyst, the reaction is improved, a large amount of impurities are avoided, the main content is improved from 50% to 90%, the yield is improved from 44% to 80% . the full-process operation is simple and controllable, the cost is low, and industrial production is easy to realize.
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Paragraph 0042; 0044; 0046-0047; 0049-0050; 0052-0053; ...
(2021/09/08)
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- Aldol Condensation Versus Superbase-Catalyzed Addition of Ketones to Acetylenes: A Quantum-Chemical and Experimental Study
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The mechanism of aldol condensation of ketones in KOH/DMSO superbasic media has been investigated using the B2PLYP(D2)/6-311+G**//B3LYP/6-31+G? quantum-chemical approach. It is found that the interaction of three ketone molecules resulting in the formation of the cyclohex-2-enone structure [isophorone or 3,5-dicyclohexyl-5-methylspiro(5.5)undec-2-en-1-one] is thermodynamically more favorable than the interaction of two, three, or four molecules of ketone, resulting in the formation of linear products of the condensation. The formation of the condensation products with the isophorone skeleton can significantly hinder the cascade reactions of ketones with acetylenes [to afford 6,8-dioxabicyclo(3.2.1)octanes or acylcyclopentenols] promoted by superbases. In particular, the kinetically more preferable reactions of autovinylation of 2-methyl-3-butyn-2-ol and autocondensation of acetone are the reasons why interaction of acetone with acetylene does not lead to the products of the cascade assemblies. The predominant formation of the products of these side reactions is confirmed experimentally.
- Orel, Vladimir B.,Vitkovskaya, Nadezhda M.,Bobkov, Alexander S.,Semenova, Nadezhda V.,Schmidt, Elena Yu.,Trofimov, Boris A.
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p. 7439 - 7449
(2021/06/21)
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- Platinum-(phosphinito-phosphinous acid) complexes as bi-talented catalysts for oxidative fragmentation of piperidinols: An entry to primary amines
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Platinum-(phosphinito-phosphinous acid) complex catalyzes the oxidative fragmentation of hindered piperidinols according to a hydrogen transfer induced methodology. This catalyst acts successively as both a hydrogen carrier and soft Lewis acid in a one pot-two steps process. This method can be applied to the synthesis of a wide variety of primary amines in a pure form by a simple acid-base extraction without further purification.
- Membrat, Romain,Vasseur, Alexandre,Moraleda, Delphine,Michaud-Chevallier, Sabine,Martinez, Alexandre,Giordano, Laurent,Nuel, Didier
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p. 37825 - 37829
(2019/12/03)
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- A new peroxo-route for the synthesis of Mg-Zr mixed oxides catalysts: Application in the gas phase acetone self-condensation
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We propose in this manuscript a new peroxo-mediated procedure for preparing magnesia-zirconia mixed oxides, with Mg/Zr molar ratio between 1 and 3, with enhanced distribution of basic sites. The mixed magnesia-zirconia oxides have been prepared from the gelled complex by Pechini-type method. The MgO-ZrO 2 materials have been characterized and used as catalysts for acetone aldol condensation. The proposed preparation method provides a high degree of molecular homogeneity and favours the formation of magnesia-stabilized zirconia phase. Acetone gas-phase self-condensation was carried out over these catalysts as model reaction requiring the presence of basic sites. The condensation yields diacetone alcohol and mesityl oxide as mean C6 products, and phorones, isophorones and mesitylene as C9 products. In comparison to Mg-Zr oxide prepared by co-precipitation, these new materials present better conversions and higher selectivity to linear dimers and trimers (as mesitylene), whereas the selectivity for isophorones is significantly lower.
- Krivtsov, Igor,Faba, Laura,Díaz, Eva,Ordó?ez, Salvador,Avdin, Viacheslav,Khainakov, Sergei,Garcia, Jose R.
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- Cr, Zr-incorporated hydrotalcites and their application in the synthesis of isophorone
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Cr3+ and Zr4+ cation-incorporated hydrotalcites (HTs) were prepared by coprecipitation method. Corresponding mixed oxide were obtained by the thermal decomposition of HTs at 773 K for 8 h and applied in the synthesis of isophorone (IP) from acetone. From the characteristic results, both Cr3+ and Zr4+ were introduced into the lattice of hydrotalcite producing the more disordered HT structures. Compared with Mg-Al mixed oxide, Cr and Zr modified mixed oxide demonstrated more amount of basic sites and stronger base strength, which were responsible for the improvement of catalytic activity. As a result, both of the modified mixed oxide exhibited IP selectivity of more than 70% under atmospheric pressure.
- Liu, Yanxia,Sun, Kunpeng,Ma, Haowen,Xu, Xianlun,Wang, Xiaolai
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experimental part
p. 880 - 883
(2010/11/04)
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- Direct addition of supercritical alcohols, acetone or acetonitrile to the alkenes without catalysts
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The reactions of the alkenes with supercritical organic compounds under non-catalytic conditions were investigated. The H and CR2OH, CH2C{double bond, long}OCH3 or CH2C{triple bond, long}N of supercritical alcohols (CHR2OH), acetone (CH3C{double bond, long}OCH3) or acetonitrile (CH3C{triple bond, long}N) added to the C{double bond, long}C bonds of alkenes form C-C bonds between the α-carbons of the supercritical organic compounds and the sp2 carbons of the alkenes.
- Kamitanaka, Takashi,Hikida, Tatsuyoshi,Hayashi, Satoshi,Kishida, Nobuhiro,Matsuda, Tomoko,Harada, Tadao
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p. 8460 - 8463
(2008/03/13)
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- Titanium(IV) chloride induced reactions of ketones and C-acylimines with dimethylcyanamide
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The reactions of ketones (benzophenone, 4-methylbenzophenone, acetophenone, acetone, and 2,2,4,4-tetramethyl-3-pentanone) and C-acylimines with dimethylcyanamide in the presence of titanium(IV) chloride were investigated. Benzophenone and 4-methylbenzophenone react with dimethylcyanamide to give 4,4-disubstituted 2-dimethylamino-3-aza-1-oxa-1,3-butadienes 5 and 4,4-disubstituted 2-dimethylanuno-1-N,N-dimethylcarbamoyl-1,3-diaza-1,3-butadienes 9. Ketones with enolizable hydrogen atoms undergo aldol reactions under these conditions. C-Acylimines 11b-11e, derived from benzil and substituted anilines, undergo [2 + 2] cycloaddition to dimethylcyanamide with subsequent ring opening to 1-(N,N-dimethylcarbamoyl)-2,3,4-triaryl-1,4-diaza-1,3-butadienes 15. 1,2-Diphenyl-2-(isopropylimino)ethanone (11a) reacts with dimethylcyanamide to give 2-dimethylamino-1-isopropyl-4,4-diphenyl-2-imidazolin-5-one (23) in a hitherto unknown multistep reaction. The structure of 23 was confirmed by an X-ray analysis. VCH Verlagsgesellschaft mbH, 1996.
- Mazik, Monika,Boese, Roland,Sustmann, Reiner
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p. 1665 - 1671
(2007/10/03)
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- Conversion of Acetone over Modified Y Zeolites, SAPO-5 and AlPO4-5
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The effect of acidity on the reactions of acetone at 350 deg C was studied with large-pore AlPO4-5 and SAPO-5 phosphates and thermochemically modified Y zeolites, which contained Al in various concentration and distribution.It was shown that the catalytic activity of hydroxyls depends on their acid strength: it decreases in the sequence SiOHAl (bridging) > POH, AlnOH (Aln - non-sketal) > SiOH.In contrast to mediumpore HZSM-5 zeolite, which yields mainly aromatics and aliphatics (most abundant is isobutene), large-pore molecular sieves yield also mesityloxide and phorones, especially at low conversion levels.The formation of the latter compounds over Y zeolites is enhanced by the non-skeletal Al species, which also increase the deactivation rate and add carbonylate-like species into the deposit.The discussion considers also steric constraints imposed by the zeolite structure.
- Kubelkova, Heyrovsky,Cejka, Jiri,Novakova, Jana,Lercher, Johannes A.,Jahn, Elke
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p. 231 - 242
(2007/10/02)
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- 172. β-Cleavage of Bis(homoallylic) Potassium Alkoxides. Two-Step Preparation of Propenyl Ketones from Carboxylic Esters. Synthesis of ar-Turmerone, α-Damascone, β-Damascone, and β-Damascenone
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The transformation of 36 bis(homoallylic) alcohols VII to alkenones IX and X via β-cleavage of their potassium alkoxides VIIa in HMPA has been investigated (cf.Scheme 2).These studies have established an order of β-cleavage for 2-propenyl, 1-methyl-2-propenyl, 2-methyl-2-propenyl, 1,1-dimethyl-2-propenyl, and benzyl groups in alkoxides 49a-56a and have allowed a comparison between the β-cleavage reaction and the oxy-Cope rearrangement in alkoxides 74a-83a.As illustrative synthetic applications, a two-step preparation of propenyl ketones 15-42 from carboxylic esters is described, together with syntheses of ar-turmerone (48), α-damascone ((E)-71), β-damascone ((E)-109), and β-damascenone ((E)-111).
- Snowden, Roger L.,Linder, Simon M.,Muller, Bernard L.,Schulte, Karl H.
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p. 1858 - 1878
(2007/10/02)
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- NUCLEOPHILIC ADDITION TO 1,2,2,6,6-PENTAMETHYL-3,5-DIMETHYLENE-4-PIPERIDONE
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Like branched primary amines, unbranched mercaptans react with 1,2,2,6,6-pentamethyl-3,5-dimethylene-4-piperidone to give products of ring opening.On the basis of the data obtained, a reaction scheme that includes the intermediate formation of 3,7-diazabicyclononan-9-one seems less likely as compared with a scheme involving elimination from the monocyclic piperidine system.It is also shown that steric interaction of the vicinal substituents is one of the important factors that promote β elimination.
- Belostotskii, A. M.,Shapiro, A. B.
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p. 665 - 669
(2007/10/02)
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- The enthalpy of acetone
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Measurements of the specific enthalpy increment of acetone are reported; 206 measurements cover the range 373.2 to 623.2 K at pressures from 0.1 to 11.9 MPa.The overall accuracy is 0.6 per cent.The specific enthalpy of the saturated liquid and of the saturated vapour and the enthalpy of vaporization are derived from the measurements.Comparison with cubic equations of state shows that the Patel-Teja equation is the best of those tested.
- Yerlett, T. K.,Wormald, C. J.
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p. 371 - 380
(2007/10/02)
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