Ambident reactivity of acetyl- and formyl-stabilized phosphonium ylides

Simple item page
dc.contributor.authorByrne, Peter A.
dc.contributor.authorKaraghiosoff, Konstantin
dc.contributor.authorMayr, Herbert
dc.contributor.funderAlexander von Humboldt-Stiftungen
dc.contributor.funderDeutsche Forschungsgemeinschaften
dc.date.accessioned2019-04-04T09:03:39Z
dc.date.available2019-04-04T09:03:39Z
dc.date.issued2016-07-08
dc.date.updated2019-03-26T17:12:07Z
dc.description.abstractThe kinetics and mechanism of the reactions of formyl-stabilized ylide Ph3P═CHCHO (1) and acetyl-stabilized ylide Ph3P═CHCOMe (2) with benzhydrylium ions (Ar2CH+, 3) were investigated by UV–vis and NMR spectroscopy. As ambident nucleophiles, ylides 1 and 2 can react at oxygen as well as at the α-carbon. For some reactions, it was possible to determine the second-order rate constant for O-attack as well as for C-attack and to derive the nucleophile-specific parameters N and sN according to the correlation lg k (20 °C) = sN(E + N) for both nucleophilic sites. Generally, O-attack of benzhydrylium ions is faster than C-attack. However, the initially formed benzhydryloxyvinylphosphonium ions can only be observed by NMR spectroscopy when benzhydryl cations with high Lewis acidity are employed. In other cases, rearrangement to the thermodynamically more stable products arising from C-attack occurs. The results derived from our investigations are employed to rationalize the behavior of ambident nucleophiles 1 and 2 in reactions with carbon-centered electrophiles in general. It is shown that the principle of hard and soft acids and bases (HSAB) and the related Klopman–Salem concept of charge and orbital control lead to incorrect predictions of regioselectivity. We also show that the rate of the Wittig reaction of ylide 2 with aldehyde 14 is significantly faster than the rate of either C- or O-attack calculated using lg k (20 °C) = sN(E + N), thus indicating that the oxaphosphetane is formed by a concerted [2 + 2] cycloaddition.en
dc.description.sponsorshipAlexander von Humboldt-Stiftung (Humboldt foundation, Humboldt Research Fellowship for Postdoctoral Researchers); Deutsche Forschungsgemeinschaft (SFB 749, Project B1)en
dc.description.statusPeer revieweden
dc.description.versionAccepted Versionen
dc.format.mimetypeapplication/pdfen
dc.identifier.citationByrne, P. A., Karaghiosoff, K. and Mayr, H. (2016) 'Ambident Reactivity of Acetyl- and Formyl-Stabilized Phosphonium Ylides', Journal of the American Chemical Society, 138(35), pp. 11272-11281. doi: 10.1021/jacs.6b06264en
dc.identifier.doi10.1021/jacs.6b06264en
dc.identifier.eissn1520-5126
dc.identifier.endpage11281en
dc.identifier.issn0002-7863
dc.identifier.journaltitleJournal of the American Chemical Societyen
dc.identifier.startpage11272en
dc.identifier.urihttps://hdl.handle.net/10468/7703
dc.identifier.volume138en
dc.language.isoenen
dc.publisherAmerican Chemical Society, ACSen
dc.relation.urihttp://pubs.acs.org/doi/abs/10.1021/jacs.6b06264
dc.rights© 2016 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/jacs.6b06264#en
dc.subjectPhosphonium ylideen
dc.subjectNucleophilicityen
dc.subjectReactivityen
dc.subjectAmbident nucleophileen
dc.subjectMarcus theoryen
dc.titleAmbident reactivity of acetyl- and formyl-stabilized phosphonium ylidesen
dc.typeArticle (peer-reviewed)en
Files
Original bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
JACS_2016,_accepted_article._Ambident_ylides.pdf
Size:
1.3 MB
Format:
Adobe Portable Document Format
Description:
Accepted version
Download
License bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
license.txt
Size:
2.71 KB
Format:
Item-specific license agreed upon to submission
Description:
Download
Collections
Chemistry - Journal Articles