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dc.contributor.authorDai, Wen
dc.contributor.authorCurran, Dennis P.
dc.contributor.authorWalton, John C.
dc.date.accessioned2020-01-21T00:35:00Z
dc.date.available2020-01-21T00:35:00Z
dc.date.issued2019-02-15
dc.identifier258002712
dc.identifierb56dd974-baff-428e-9811-49387ea92a62
dc.identifier85061609832
dc.identifier30663305
dc.identifier000459367100043
dc.identifier.citationDai , W , Curran , D P & Walton , J C 2019 , ' EPR and preparative studies of 5- endo cyclizations of radicals derived from alkenyl NHC-boranes bearing tert -butyl ester substituents ' , The Journal of Organic Chemistry , vol. 84 , no. 4 , pp. 2102-2111 . https://doi.org/10.1021/acs.joc.8b03112en
dc.identifier.issn0022-3263
dc.identifier.otherORCID: /0000-0003-2746-6276/work/56638867
dc.identifier.urihttps://hdl.handle.net/10023/19319
dc.descriptionJ.C.W. thanks EaStCHEM for financial support, and D.P.C. thanks the US National Science Foundation. Computational support was provided through the EaStCHEM Research Computing Facility.en
dc.description.abstractRadical H atom abstraction from a set of N-heterocyclic carbene (NHC) complexes of alkenylboranes bearing two tert-butyl ester substituents was studied by EPR spectroscopy. The initial boraallyl radical intermediates rapidly ring closed onto the O atoms of their distal ester groups in 5-endo mode to yield 1,2-oxaborole radicals. Unexpectedly, two structural varieties of these radicals were identified from their EPR spectra. These proved to be two stable rotamers, in which the carbonyl group of the tert-butyl ester was oriented toward and away from the NHC ring. These rotamers were akin to the s-trans and s-cis rotamers of α,β-unsaturated carbonyl compounds. Their stability was attributed to the quasi-allylic interaction of their unpaired electrons with the carbonyl units of their adjacent ester groups. EPR spectroscopic evidence for two rotamers of the analogous methyl ester containing NHC-oxaborole radicals was also obtained. An improved synthetic procedure for preparing rare NHC-boralactones was developed involving treatment of the alkenyl NHC-boranes with AIBN and tert-dodecanethiol.
dc.format.extent10
dc.format.extent749527
dc.language.isoeng
dc.relation.ispartofThe Journal of Organic Chemistryen
dc.subjectQD Chemistryen
dc.subjectOrganic Chemistryen
dc.subjectNDASen
dc.subject.lccQDen
dc.titleEPR and preparative studies of 5-endo cyclizations of radicals derived from alkenyl NHC-boranes bearing tert-butyl ester substituentsen
dc.typeJournal articleen
dc.contributor.institutionUniversity of St Andrews. School of Chemistryen
dc.contributor.institutionUniversity of St Andrews. EaSTCHEMen
dc.identifier.doihttps://doi.org/10.1021/acs.joc.8b03112
dc.description.statusPeer revieweden
dc.date.embargoedUntil2020-01-21


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