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Developments in the hydrogenation of challenging substrates utilising transition metal complexesCarpenter, Ian January 2015 (has links)
This thesis describes the developments of new protocols for the hydrogenation of challenging substrates. Three specific substrates were highlighted for study after an initial review of the literature; benzofurans, esters and bulky ketones. Chapter 1 details a review of the hydrogenation of challenging unsaturated substrates, highlighting areas where development is still required. Chapter 2 describes studies on the hydrogenation of 2,3-benzofuran. While a benzofuran hydrogenation catalysts was optimised, severe conditions were required to facilitate the reaction, and not found to be applicable for more elaborate substrates. We therefore considered an alternative process of enantioselective hydrogenation of benzofuranyl ketones followed by heterogeneous hydrogenation. A good process for transfer hydrogenation of a range of these hitherto unstudied substrates was developed along with greater understanding. The hydrogenation of esters is another challenge in the catalytic reduction field, so was also selected for study, with the results described in Chapter 3. After screening a range of catalysts of types [RuCl₂ (diphosphine)(diamine)] and [RuCl₂ (PNX)(DMSO)], good catalysts were identified. Successful hydrogenation of a range of esters, under mild conditions was achieved using [RuCl₂ (1,3-bisdiphenylphosphinepropane)(2-aminomethylpyridine)] using high concentrations of base co-catalyst. [RuCl₂ ((2-(diphenylphosphanylbenzyl)ethane-1,2-diamine)(DMSO)] combined with 15-25 mol% of a basic co-catalyst have been shown to be active at near ambient conditions in the hydrogenation of aromatic esters. Chapter 4 related to studies where the activity of Ru, Ir and Rh complexes of the same tridentate ligand were tested in the hydrogenation of ketones that would be regarded as sluggish substrates. Highly active and selective catalysts for the hydrogenation of bulky acetophenone derivatives were found using iridium complexes of PNX ligands (formed in situ). The highest selectivity was obtained with acetophenone substrates containing iso-propyl and cyclohexyl substituents, or medicinally important piperdinyl groups. In the best cases over 90% e.e. was observed with high conversions and with only 0.1 mol% of catalyst.
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Ketone catalyzed diastereoselective and enantioselective epoxidation of olefins: catalyst design and syntheticapplication焦關勝, Jiao, Guansheng. January 2000 (has links)
published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy
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Studies on solution and solid phase biotransformationsMartins, Jose Alberto Ribeiro January 2000 (has links)
No description available.
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The parallel synthesis of natural product familiesCatterick, David January 1998 (has links)
No description available.
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NMR and neutron scattering investigations of molecular motion in the solid stateGreen, R. M. January 1988 (has links)
No description available.
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Design of new asymmetric copper(I)-catalysts for conjugate addition chemistryBennett, Malcolm William January 1999 (has links)
No description available.
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A synthetic approach to Câ†2 symmetric guanidine bases and the synthesis of model compounds of ptilomycalin AHoward-Jones, Andrew Glyn January 2000 (has links)
No description available.
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Synthesis of macrocyclic 1,3-diketones from metacyclophanes and their applications in organic synthesis.January 1994 (has links)
by Siu-leung Ng. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1994. / Includes bibliographical references (leaves 61-62). / Acknowledgments --- p.i / Content --- p.ii / List of Schemes --- p.iii / List of Tables --- p.iv / List of Spectra --- p.v / Abstract --- p.viii / Abbreviations --- p.x / Chapter I. --- Introduction --- p.1 / Chapter II. --- Literature survey / Chapter II.1. --- Ring expansion of cyclic enamines via a [2+2]cycloaddition --- p.4 / Chapter II.2. --- The Ito-Saegusa protocol --- p.6 / Chapter II.3. --- "The Suzuki-Watanabe-Noyori palladium(0)-catalyzed ring opening of cyclic α,β-epoxy ketones" --- p.7 / Chapter III. --- Synthetic plan --- p.9 / Chapter IV. --- Results and discussion / Chapter IV. 1. --- General routes to [n]metacyclophanes (24) and (n+2)- methoxy[n]metacyclophane 35 --- p.15 / Chapter IV.2. --- Birch reduction of 24 and 35 and ozonolvsis of 25 and 36 --- p.17 / Chapter IV.3. --- Synthetic applications / Chapter IV.3.1. --- Synthesis of heterocyclophanes --- p.27 / Chapter IV.3.2. --- Synthesis of exaltone (8) --- p.28 / Chapter V. --- Conclusion --- p.30 / Chapter VI. --- Experimental --- p.31 / Chapter VII. --- References --- p.61 / Chapter VIII. --- 1H and 13C NMR spectra of selected compounds --- p.63
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The mechanism of the normal Gricnard addition reaction with ketones and nitrilesArnott, Robert Charles 08 1900 (has links)
No description available.
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Investigations in dienamine chemistry.Simpson, Richard. January 1991 (has links)
Reaction of the pyrrolidine dienamines of ~1,8a-2-octalones with methyl vinyl
ketone is complex. In methanol as solvent, the reaction occurs primarily with
the linear dienamine isomer and results in annulation of the 8,8a-positions and,
to a lesser extent, the 1,2-positions to give the corresponding octahydro-1 Hbenzo[d]naphthalene-2,10(3H,111-1)-dione and 3,4,5,6,7,8,8a,9-ctahydrophenanthren-2(10H)-one respectively. In toluene the dienamines react mainly in their cross-conjugated form. Diels-Alder addition of methyl vinyl ketone occurs across the 3,8a-positions to give the corresponding 9-acetylperhydro-2,4aethanonaphthalen-3-one and annulation of the 2,3-positions gives the 4,4a,5,5a,6,7,8,9-octahydroanthracen-2(3H)-one.
The reaction of methyl vinyl ketone with the pyrrolidine dienamine of 4amethyl-
5-oxo-~ 1,8a-2-octalone is reported to give the aromatic product 3a, 7dimethyl-
2,3,3a,4,5,6-hexahydrophenalen-3,6-dionearisingfromp,o-annulation
and in a related investigation with dienamines derived from isophorone it was
reported that only products of Stork alkylation and Diels-Alder cycloaddition
were isolated, there being no evidence for the reaction of methyl vinyl ketone
with either the endo- or exocyclic o-positions of the dienamines.
In an attempt to ascertain the reason for the apparently random changes in the
regioselectivity of these related reactions some of this work was repeated and
the reaction of methyl vinyl ketone applied to two other dienamines derived
from 5,6,7,7a-tetrahydroindan-5-one and 4a,6-dimethyl-5-oxo-~1,8a-2-octalone.
The reactions proved to be more complex than reported and several
additional products have been isolated. Finally, reaction of phenyl vinyl ketone with dienamines derived from a1,8a_2-octalone was investigated. With the exception of the reaction of the 4amethyl dienamine, the main products isolated were those arising from addition of p.henyl vinyl ketone across the 3,8a-position to give the corresponding 9-benzoylperhydro-,4a-ethanonaphthalen-3-one. Reaction of the 4a-methyl dienamine with two equivalents of phenyl vinyl ketone gave a product tentatively assigned as the octahydrophenalenone. The mechanism of formation and spectral properties of the various products are discussed. / Thesis (Ph.D.)-University of Natal, 1991.
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