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1	Synthesis, structure and pyrolysis of stabilised phosphonium ylides containing saturated oxygen heterocycles Aitken, R.A., Karodia, Nazira, McCarron, H.B., Rouxel, C., Sahabo, Nina Carole, Slawin, A.M.Z. 05 January 2016 (has links) yes / A range of twelve stabilised phosphonium ylides containing tetrahydrofuran, tetrahydropyran or 2,2- dimethyl-1,3-dioxolane rings have been prepared and fully characterised, including one X-ray structure determination of each type. The X-ray structures confirm the PvC and CvO functions to be syn and all the compounds undergo thermal extrusion of Ph3PO to give the corresponding alkynes. In some cases there is also competing loss of Ph3P to give different carbene-derived products and evidence has been obtained for the generation of 2-phenyloxete in this way. Raising the pyrolysis temperature leads in several cases to new secondary reactions of the alkyne products involving a sequence of alkyne to vinylidene isomerisation, intramolecular CH insertion, and retro Diels Alder reaction.
2	Studies in cyclic ether synthesis : Part one: Domino cyclisations to cyclic ethers -- Part two: Synthetic studies towards neopeltolide Cadou, Romain F. January 2010 (has links) Tetrahydrofuran (THF) and tetrahydropyran (THP) rings are commonly found in a wide range of natural products and biologically active compounds. In total synthesis, the formation of THF/THP motifs is often the key step but existing methods often involve numerous steps and low overall efficiencies. Part one of this thesis details the development of a practical method for the synthesis of THF rings by the controlled mono-addition/cyclisation of organolithium species to C2-symmetric diepoxides (Scheme A-1). This method can also be applied to the synthesis of bis-THF rings from triepoxides and has potential applications in more complex cascade reactions. A similar cyclisation process providing THF rings from epoxyaldehydes is also described. Part two of this thesis details our efforts towards the synthesis of the marine macrolide neopeltolide. Wright and co-workers reported the isolation of neopeltolide 211 from a deep-water sponge of the family neopeltidae off the north coast of Jamaica. The structure, which was assigned by NMR and HRMS studies and reassigned by total synthesis, contains a 14-membered macrolactone, a 2,6-cis THP ring and an unsaturated oxazole side-chain. Chapter four describes the synthesis of the C2-C8 and C9-C16 fragments (Scheme A-2). Chapter five details our initial attempts in the coupling of subunits 268 and 320, as well as a revised synthetic strategy that allowed us to successfully couple C2-C9 alkyne 347 with C10-C16 aldehyde 348 and the preparation of an advanced intermediate 364 (Scheme A-3). 547.6
3	Synthesis with Perfect Atom Economy: Generation of Furan Derivatives by 1,3-Dipolar Cycloaddition of Acetylenedicarboxylates at Cyclooctynes Banert, Klaus, Bochmann, Sandra, Ihle, Andreas, Plefka, Oliver, Taubert, Florian, Walther, Tina, Korb, Marcus, Rüffer, Tobias, Lang, Heinrich 25 September 2014 (has links) (PDF) Cyclooctyne and cycloocten-5-yne undergo, at room temperature, a 1,3-dipolar cycloaddition with dialkyl acetylenedicarboxylates 1a,b to generate furan-derived short-lived intermediates 2, which can be trapped by two additional equivalents of 1a,b or alternatively by methanol, phenol, water or aldehydes to yield polycyclic products 3b–d, orthoesters 4a–c, ketones 5 or epoxides 6a,b, respectively. Treatment of bis(trimethylsilyl) acetylenedicarboxylate (1c) with cyclooctyne leads to the ketone 7 via retro-Brook rearrangement of the dipolar intermediate 2c. In all cases, the products are formed with perfect atom economy. Technische Universität Chemnitz Publikationsfonds Kaskadenreaktionen Cyclopropene Diels-Alder-Reaktionen dipolare Zwischenstufen Epoxide Orthoester Sauerstoffheterocyclen Reaktionsmechanismen Retro-Brook-Reaktionen gespannte Verbindungen cascade reactions cyclopropenes Diels-Alder reactions dipolar intermediates epoxides orthoesters oxygen heterocycles reaction mechanisms retro-Brook reactions strained compounds Technische Universität Chemnitz Publication funds ddc:540 Epoxide Ortho-Ester Sauerstoffheterocyclen
4	Synthesis with Perfect Atom Economy: Generation of Furan Derivatives by 1,3-Dipolar Cycloaddition of Acetylenedicarboxylates at Cyclooctynes Banert, Klaus, Bochmann, Sandra, Ihle, Andreas, Plefka, Oliver, Taubert, Florian, Walther, Tina, Korb, Marcus, Rüffer, Tobias, Lang, Heinrich 25 September 2014 (has links) Cyclooctyne and cycloocten-5-yne undergo, at room temperature, a 1,3-dipolar cycloaddition with dialkyl acetylenedicarboxylates 1a,b to generate furan-derived short-lived intermediates 2, which can be trapped by two additional equivalents of 1a,b or alternatively by methanol, phenol, water or aldehydes to yield polycyclic products 3b–d, orthoesters 4a–c, ketones 5 or epoxides 6a,b, respectively. Treatment of bis(trimethylsilyl) acetylenedicarboxylate (1c) with cyclooctyne leads to the ketone 7 via retro-Brook rearrangement of the dipolar intermediate 2c. In all cases, the products are formed with perfect atom economy. info:eu-repo/classification/ddc/540 ddc:540

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