33,902 research outputs found
Dialogical Skirmishes
No full textTan was guest editor for 'And Now China?', a special print edition of the Ctrl+P journal, which critically responded to the celebratory rhetoric’s of ‘China Now’ and other celebratory markers of China's global ascent in 2008. As well as the introductory article 'Dialogical Skirmishes', Tan also interviewed Hans Ulrich Obrist
Evidence for erbium-erbium energy migration in erbium(III) bis(perfluoro-p-tolyl)phosphinate
No full textCopyright 2008 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. This article appeared in Applied Physics Letters 92, 103303 (2008) and may be found at
Toward the Synthesis of (–)-TAN-2483B Lactam Analogues
No full textNatural products continue to be an abundant source of lead compounds for drug discovery and development. (–)-TAN-2483A and (–)-TAN-2483B, isolated from the culture of a filamentous fungus, incorporate an unusual furo[3,4-b]pyran-5-one scaffold. TAN-2483A was initially reported to inhibit the c-Src tyrosine kinase enzyme, a potential anticancer target, and parathyroid hormone-induced bone resorption. TAN-2483B, on the other hand, was not isolated in sufficient quantities for biological testing. The synthesis of TAN-2483B is therefore desirable from a drug discovery perspective. Several analogues of TAN-2483B that are functionalised at the propenyl sidechain have previously been synthesised in the Harvey group and have shown promising biological activity. For example, the (Z)-ethyl ester analogue showed micromolar inhibition of HL-60 cells and Bruton’s tyrosine kinase, a protein involved in B-cell maturation that is implicated in certain cancers. The lactone moiety of TAN-2483B and its sidechain analogues, however, appears to be unstable to nucleophilic attack.
The aim of this thesis was to investigate the viability of a synthetic route toward lactam analogues of TAN-2483B. It was proposed that substituting the lactone for a lactam would increase the stability of the compound in nucleophilic media. Moreover, the lactam nitrogen may provide a site for further functionalisation of the compound for future structure-activity relationship studies. Because installation of the (Z)-ethyl ester sidechain via Wittig conditions has previously been found to be more facile than installation of the (E)-propenyl sidechain found in the natural product, investigations into forming the lactam ring system were carried out on the ethyl ester advanced intermediates. Reductive amination of a ketone intermediate was envisaged to install the amine prior to a palladium-catalysed carbonylation/lactam formation step. The promising bioactivity of the (Z)-ethyl ester analogue was anticipated to be retained in the target lactam analogues.
It was found that the substrates of the proposed reductive amination, the advanced ketone intermediates, were incompatible with the tested conditions, presumably due to base sensitivity. Three by-products from the reductive amination experiments were isolated and tentatively characterised by NMR spectroscopy and HRMS. An alternative route toward lactam analogues of TAN-2483B, via intermediate amines accessed by the substitution of an activated alcohol, was briefly investigated with encouraging results.
Further optimisation of the synthetic route toward analogues of TAN-2483B was also achieved. Removal of a purification step enabled the more expedient two-step synthesis of a diol intermediate. The two-step transformation to (Z)- and (E)-ethyl ester intermediates, via sodium periodate-mediated diol cleavage and Wittig olefination, proceeded in the highest yield obtained to date. Investigations into the desilylation of a trimethylsilyl-protected acetylene were also conducted.
Although lactam analogues of TAN-2483B were not obtained in this study, progress was made toward their synthesis. The alternative route toward amines that was briefly explored here appears promising, and work is ongoing in the Harvey group to access lactam (and other) analogues of TAN-2483B, in addition to the natural product itself
Free thinking - running
No full textWe've been running for two million years give or take. Shahidha Bari and Laurence Scott explore contemporary running as solitary inspiration and communal activity with the Geographer and 1999 Scottish Hill Running Champion, Hayden Lorimer, the artists Kai Syng Tan and Angus Farquhar, and the literary scholar and bare-foot artiste, Vybarr Cregan-Reid. Conversation ranges from feeling empowered on city streets to teaming up with the wind to the horrid history of the treadmill and explore whether Running deserves better representation in the arts. Guests: Vybarr Cregan-Reid - author of Footnotes How Running Makes Us Human Angus Farquhar, Creative Director of NVA Public Art, author of a blog 'The Grim Runner' Hayden Lorimer Running Geographer Kai Syng Tan, Artist and curator of a biennial festival Run Run Run Producer: Jacqueline Smith
Neuro-futurism and re-imagining leadership: an A-Z towards collective liberation
No full textRe-Imagining Leadership with Neuro-Futurism: An A-Z Towards Collective Liberation (Kai Syng Tan, Palgrave Macmillan 2024) is a rip-roaring manifesto that introduces ‘neuro-futurism’ as a multi-faceted toolkit, and re-claims ways to think about and do ‘leadership’ as a diversified, beyond-colonial, neuro-queered and (co-)creative change- and future-making practice. Colliding mobilities, neuro-queering, the arts and culture, critical leadership studies, social justice, creative pedagogy, futurity and Daoist cosmology for the first time, the short, sweet and spicy hand-book celebrates the Dangerous, Demeaning and Dirty labour of Deviant/Defiant culture-workers often side-lined in (leadership) scholarship across 26 break-neck, fist-stomping chapters and 40 original images and maps. Instead of a trait or talent centred around individuals, hierarchy, organisations, positions, genes or luck, this book admonishes white-supremacist-cis-het-neuro-normative-capitalist-patriarchal forms of power and knowledge. Punchy, punching up and pulling no punches, and riffing on how ‘leadership’ originally refers to travelling, endurance and guidance, Re-Imagining Leadership with Neurop-Futurism is a call to arms, feet, sole-soul, to co-create tables/houses/worlds that profit (neuro-)divergent People, Planet, Poetry and Play. The deadline is 2050, so we’re running out of time. Are you ready for an extra-ordinary adventure? My book will be part of the Studies in Mobilities, Literature, and Culture series (editors: Aguiar Marian, Mathieson Charlotte, Pearce Lynne), the inaugural publication for which I wrote a chapter Running (in) Your City, which has been praised as ‘exciting’)
Synthesis of Highly Functionalised Furo[3,4-b]pyrans: Towards the Fungal Metabolite (−)-TAN-2483B
No full textCarbohydrate-derived cyclopropanes combine both the stereochemical wealth of carbohydrates and the reactivity of cyclopropanes. A diverse variety of reaction modes for these cyclopropyl carbohydrates can be harnessed for the synthesis of natural products and other targets.
The natural products (−)-TAN-2483A and (−)-TAN-2483B are fungal secondary metabolites displaying a variety of bioactivities such as inhibition of c-src kinase action and parathyroid hormone-induced bone resorption. This thesis described several synthetic approaches to the natural product (−)-TAN-2483B and analogues of (−)-TAN-2483B employing cyclopropane ring expansion.
The synthetic route to (−)-TAN-2483B began with the readily available substrate D-mannose. The pyran ring unsaturation of the natural product was established by a cyclopropanation-ring expansion sequence. A synthetic strategy via dichlorocyclopropane-based intermediates is described in chapter 2. This being unsuccessful, an alternative approach via 2-fomyl-glycal was developed in chapter 3. The chapter 2 and 3 provided a solid background for the achievement of the analogues synthesis illustrated in chapter 4 via dibromocyclopropane. Lewis acid-mediated alkynylation followed by Pdcatalysed carbonylative lactonisation was successfully utilised in the revelation of the furo[3,4-b]pyran ring skeleton. This route afforded analogues of TAN-2483B; the Z-and E-unsaturated ethyl esters 140 and 141 and hydroxy(−)-TAN-2483B 145. The total synthesis of (−)-TAN-2483B was not achieved due to unforeseen obstacles encountered in the deoxygenation of the side arm of 335 (Chapter 4) into the E-propenyl side arm of (−)-TAN-2483B
A Short Note on the Infinity Product Tan(z) Function.pdf
No full textWe present a novel derivation of the infinite product of the tangent function, tan(z), expressed in terms of trigonometric expressions including Euler’s Sinc function and Viète’s formula, along with their generalizations</p
A Short Note on the Infinity Product Tan (z) Function
No full textWe derive the infinite product of the tangent function, Tan(z), expressed in terms of trigonometric expressions such as Euler's Sinc function and Viète's formula, along with their generalizations. All the results presented in this work are novel.</p
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