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Comparing and taming the reactivity of HWE and Wittig reagents with cyclic hemiacetals Carrillo Arregui, Jokin Costa i Arnau, Anna M. Sidera Portela, Mireia Vilarrasa i Llorens, Jaume Química orgànica Reactivitat (Química) Nomenclatura química Síntesi orgànica Organic chemistry Reactivity (Chemistry) Chemical nomenclature Organic synthesis A practical solution to the formation of mixtures of E/Z and open/cyclic isomers in the reaction of (2R,4S)-4-hydroxy-2-methylpentanal (as its hemiacetal, a lactol) with conjugated phosphoranes (stabilised Wittig reagents) and Horner-Wadsworth-Emmons reagents is disclosed. The HWE reaction has a strong bias to give oxolanes. On the other hand, stabilised Wittig reagents give unsaturated carboxyl derivatives of configuration E (major) and oxolanes (minor); the latter can be avoided by addition of CF3CH2OH or using morpholine amide phosphorane. 2013-09-03T11:22:53Z 2013-09-03T11:22:53Z 2011 2013-09-03T11:22:53Z info:eu-repo/semantics/article info:eu-repo/semantics/acceptedVersion 0040-4039 https://hdl.handle.net/2445/45524 598862 eng Versió postprint del document publicat a: http://dx.doi.org/10.1016/j.tetlet.2011.07.121 Tetrahedron Letters, 2011, vol. 52, num. 40, p. 5153-5156 http://dx.doi.org/10.1016/j.tetlet.2011.07.121 (c) Elsevier Ltd, 2011 info:eu-repo/semantics/openAccess 5 p. application/pdf Elsevier Ltd Articles publicats en revistes (Química Inorgànica i Orgànica)