- Synthesis of bimetallic Zr(Ti)-naphthalendicarboxylate MOFs and their properties as Lewis acid catalysis
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Bimetallic Zr(Ti)-NDC based metal-organic frameworks (MOFs) have been prepared by incorporation of titanium(iv) into zirconium(iv)-NDC-MOFs (UiO family). The resulting materials maintain thermal (up to 500 °C), chemical and structural stability with respect to parent Zr-MOFs as can be deduced from XRD, N2 adsorption, FTIR and thermal analysis. The materials have been studied in Lewis acid catalyzed reactions, such as, domino Meerwein-Ponndorf-Verley (MPV) reduction-etherification of p-methoxybenzaldehyde with butanol, isomerization of α-pinene oxide and cyclization of citronellal.
- Rasero-Almansa, Antonia M.,Iglesias, Marta,Sánchez, Félix
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p. 106790 - 106797
(2016/11/23)
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- Ring-opening of epoxides promoted by organomolybdenum complexes of the type [(η5-C5H4R)Mo(CO)2(η3-C3H5)] and [(η5-C5H5)Mo(CO)3(CH2R)]
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The cyclopentadienyl molybdenum carbonyl complexes [(η5-C5H4R)Mo(CO)2(η3-C3H5)] and [(η5-C5H5)Mo(CO)3(CH2R)] (R = H, COOH) have been shown to promote acid-catalysed reactions in liquid phase, under moderate conditions. The catalytic alcoholysis of styrene oxide with ethanol at 35 °C gave 2-ethoxy-2-phenylethanol in 100% yield within 30 min for the dicarbonyl complexes and 3-6 h for the tricarbonyl complexes. Steady catalytic performances were observed in consecutive runs with the same catalytic solution, suggesting fairly good catalytic stability. In the second acid-catalysed reaction studied, the isomerization of α-pinene oxide at 55 °C gave campholenic aldehyde and trans-carveol in a total yield of up to 86% at 100% conversion. Chemoselectivity is shown to be solvent dependent.
- Bruno, Sofia M.,Gomes, Ana C.,Abrantes, Marta,Valente, Anabela A.,Pillinger, Martyn,Gon?alves, Isabel S.
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p. 179 - 183
(2015/10/19)
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- Application of an indenyl molybdenum dicarbonyl complex in the isomerisation of α-pinene oxide to campholenic aldehyde
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The complex [{(η5-Ind)Mo(CO)2(μ-Cl)} 2] (1) has been tested for the industrially relevant catalytic isomerisation of α-pinene oxide (PinOx) to campholenic aldehyde (CPA) in the liquid phase. PinOx conversion and CPA selectivity are strongly influenced by the solvent employed. Complete conversion of PinOx was achieved within 1 min at 55 °C or 30 min at 35 °C using 1,2-dichloroethane as solvent, giving CPA in 68% yield. Other products included trans-carveol, iso-pinocamphone and trans-pinocarveol. The stability of 1 under the reaction conditions used was investigated by using FT-IR spectroscopy and electrospray ionisation mass spectrometry (ESI-MS) to characterise recovered solids. In the presence of air/moisture 1 undergoes oxidative decarbonylation upon dissolution to give oxomolybdenum species that are proposed to include a tetranuclear oxomolybdenum(v) complex. Conversely, ESI-MS studies of 1 dissolved in dry acetonitrile show mononuclear species of the type [IndMo(CO)2(CH 3CN)n]+. The crystal structure of the ring-slipped dicarbonyl complex [(η3-Ind)Mo(CO) 2Cl(CH3CN)2] (2) (obtained after dissolution of 1 in acetonitrile) is reported. the Partner Organisations 2014.
- Bruno, Sofia M.,Gomes, Ana C.,Gamelas, Carla A.,Abrantes, Marta,Oliveira, M. Concei??o,Valente, Anabela A.,Almeida Paz, Filipe A.,Pillinger, Martyn,Rom?o, Carlos C.,Gon?alves, Isabel S.
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p. 3172 - 3180
(2014/07/07)
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- Aminium Salts Catalyzed Rearrangement of α-Pinene and β-Ionone Oxides
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β-ionone and α-pinene oxides 1,3 isomerize rapidly and selectively to 1-(1,2,2-trimethylcyclopent-1-yl)-pent-2-en-1,4-dione 2 and the industrially important 2,2,3-trimethyl-3-cyclopentene acetaldehyde 4, under the influence of catalytic amounts of aminium salts A, B.In order to find insights into the mechanism of our procedure, protic and Lewis acids-catalyzed rearrangements have also been reconsidered.
- Lopez, Luigi,Mele, Giuseppe,Fiandanese, Vito,Cardellicchio, Cosimo,Nacci, Angelo
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p. 9097 - 9106
(2007/10/02)
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- Studies on the Oxidation of cis- and trans-Pinane with Molecular Oxygen
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The pinanes are preferably attacked at the tertiary C-H bond in 2-position, but products of the oxidative attack at the secondary C-H-bonds in 3- and 4-position are also found.At 100 deg C cis-pinane is attacked more easily than trans-pinane (kcis : ktrans = 6.4), the relative rates of attack at the secondary C-H bonds in positions 3 and 4 with respect to the tertiary C-H bond in 2-position were also determined (in cis-pinane ksec : ktert = 0.027; in trans-pinane ksec : ktert = 0.20).After the attack at the 2-C-H bond the radical formed can either react with oxygen to form the corresponding cis- and trans-peroxy radicals and further to give cis- and trans-2-hydroperoxy pinane or fragmentate to the monocyclic radical derived from α-terpinene, giving as a final products α-terpinene hydroperoxide and the bicyclic 8-hydroperoxy 4,4,8-trimethyl 2,3-dioxabicyclononane.The corresponding alcohols were found after reduction with sodium sulphite.The oxidation at position 2 of the pinanes delivers not only the cis- and trans-hydroperoxide but also, as short-lived intermediates, the corresponding 2-pinanyloxy radicals.These radicals fragmentate forming a carbon radical with cyclobutane structure whose oxidation products were identified.Besides fragmentation of the 2-pinanyloxy radical also an intramolecular H-transfer from the methyl group in 9-position to the oxygen of the trans-pinanyloxy radical takes place leading to 9-hydroperoxy trans-pinane-2-ol.
- Brose, Thomas,Pritzkow, Wilhelm,Thomas, Gerda
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p. 403 - 409
(2007/10/02)
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- SYNTHESIS AND STEREOCHEMISTRY OF SECONDARY AMINES OF THE 2,6,6-TRIMETHYLBICYCLOHEPTANE SERIES
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1S,2S,3R-N-Alkyl-2,6,6-trimethylbicyclohept-3-ylamines were synthesized by the catalytic hydroamination of 1R,2R,3R-pinan-3-ol (isopinocampheol) with aliphatic nitriles.The absolute configuration of the obtained compounds was determined.The reaction takes place strictly stereospecifically through the epimarization of 1R,2R-pinan-3-one to 1S,2S-pinan-3-one.
- Kalechits, G. V.,Kozlov, N. G.,Vyalimyae, T. K.
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p. 2097 - 2101
(2007/10/02)
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- ORGANOBORANES FOR SYNTHESIS. 3. OXIDATION OF ORGANOBORANES WITH AQUEOUS CHROMIC ACID. A CONVENIENT SYNTHESIS OF KETONES FROM ALKENES VIA HYDROBORATION
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Organoboranes react with alkaline hydrogen peroxide to provide a wide variety of alcohols.These alcohols can be taken up in ether solvent and converted without isolation into the corresponding ketones by treatment with chromic acid.Organoboranes can also be oxidized directly with chromic acid to the corresponding ketones.The chromic acid oxidation of organoboranes provides a new, convenient procedure for the synthesis of α-substituted cycloalkanones via hydroboration.The conversion of organoboranes into ketones proceeds through the intermediate alcohol.Representative cycloalkanones and α-methylcycloalkanones have been prepared from the corresponding alkenes via hydroboration, followed by chromic acid oxidation.
- Brown, Herbert C.,Garg, Chandra P.
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p. 5511 - 5514
(2007/10/02)
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