Unequivocal experimental evidence for a unified lithium salt-free Wittig reaction mechanism for all phosphonium ylide types: reactions with β-heteroatom-substituted aldehydes are consistently selective for cis-oxaphosphetane-derived products

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dc.contributor.authorByrne, Peter A.
dc.contributor.authorGilheany, Declan G.
dc.contributor.funderIrish Research Council for Science, Engineering and Technologyen
dc.contributor.funderUniversity College Dublinen
dc.date.accessioned2019-04-04T09:18:04Z
dc.date.available2019-04-04T09:18:04Z
dc.date.issued2012-05-07
dc.date.updated2019-03-26T17:23:45Z
dc.description.abstractThe true course of the lithium salt-free Wittig reaction has long been a contentious issue in organic chemistry. Herein we report an experimental effect that is common to the Wittig reactions of all of the three major phosphonium ylide classes (non-stabilized, semi-stabilized, and stabilized): there is consistently increased selectivity for cis-oxaphosphetane and its derived products (Z-alkene and erythro-β-hydroxyphosphonium salt) in reactions involving aldehydes bearing heteroatom substituents in the β-position. The effect operates with both benzaldehydes and aliphatic aldehydes and is shown not to operate in the absence of the heteroatom substituent on the aldehyde. The discovery of an effect that is common to reactions of all ylide types strongly argues for the operation of a common mechanism in all Li salt-free Wittig reactions. In addition, the results are shown to be most easily explained by the [2+2] cycloaddition mechanism proposed by Vedejs and co-workers as supplemented by Aggarwal, Harvey, and co-workers, thus providing strong confirmatory evidence in support of that mechanism. Notably, a cooperative effect of ortho-substituents in the case of semi-stabilized ylides is confirmed and is accommodated by the cycloaddition mechanism. The effect is also shown to operate in reactions of triphenylphosphine-derived ylides and has previously been observed for reactions under aqueous conditions, thus for the first time providing evidence that kinetic control is in operation in both of these cases.en
dc.description.sponsorshipIrish Research Council for Science, Engineering and Technology (EMBARK Scholarship); University College Dublin (President’s Research Fellowship)en
dc.description.statusPeer revieweden
dc.description.versionAccepted Versionen
dc.format.mimetypeapplication/pdfen
dc.identifier.citationByrne, P. A. and Gilheany, D. G. (2012) 'Unequivocal Experimental Evidence for a Unified Lithium Salt-Free Wittig Reaction Mechanism for All Phosphonium Ylide Types: Reactions with β-Heteroatom-Substituted Aldehydes Are Consistently Selective for cis-Oxaphosphetane-Derived Products', Journal of the American Chemical Society, 134(22), pp. 9225-9239. doi: 10.1021/ja300943zen
dc.identifier.doi10.1021/ja300943zen
dc.identifier.eissn1520-5126
dc.identifier.endpage9239en
dc.identifier.issn0002-7863
dc.identifier.journaltitleJournal of the American Chemical Societyen
dc.identifier.startpage9225en
dc.identifier.urihttps://hdl.handle.net/10468/7705
dc.identifier.volume134en
dc.language.isoenen
dc.publisherAmerican Chemical Society, ACSen
dc.relation.urihttp://pubs.acs.org/doi/abs/10.1021/ja300943z
dc.rights© 2012 American Chemical Society. This document is the Accepted Manuscript version of a Published Work that appeared in final form in Journal of the American Chemical Society, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://pubs.acs.org/doi/abs/10.1021/ja300943zen
dc.subjectAldehydesen
dc.subjectChemical reactionsen
dc.subjectOlefinsen
dc.subjectOrganic compoundsen
dc.subjectAliphatic aldehydesen
dc.subjectAqueous conditionen
dc.subjectCooperative effectsen
dc.subjectDerived productsen
dc.subjectErythroen
dc.subjectExperimental evidenceen
dc.subjectHeteroatom substituentsen
dc.subjectKinetic controlen
dc.subjectOrganic Chemistryen
dc.subjectWittig reactionen
dc.titleUnequivocal experimental evidence for a unified lithium salt-free Wittig reaction mechanism for all phosphonium ylide types: reactions with β-heteroatom-substituted aldehydes are consistently selective for cis-oxaphosphetane-derived productsen
dc.typeArticle (peer-reviewed)en
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