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EPR and preparative studies of 5-endo cyclizations of radicals derived from alkenyl NHC-boranes bearing tert-butyl ester substituents
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dc.contributor.author | Dai, Wen | |
dc.contributor.author | Curran, Dennis P. | |
dc.contributor.author | Walton, John C. | |
dc.date.accessioned | 2020-01-21T00:35:00Z | |
dc.date.available | 2020-01-21T00:35:00Z | |
dc.date.issued | 2019-02-15 | |
dc.identifier | 258002712 | |
dc.identifier | b56dd974-baff-428e-9811-49387ea92a62 | |
dc.identifier | 85061609832 | |
dc.identifier | 30663305 | |
dc.identifier | 000459367100043 | |
dc.identifier.citation | Dai , 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.8b03112 | en |
dc.identifier.issn | 0022-3263 | |
dc.identifier.other | ORCID: /0000-0003-2746-6276/work/56638867 | |
dc.identifier.uri | https://hdl.handle.net/10023/19319 | |
dc.description | J.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.abstract | Radical 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.extent | 10 | |
dc.format.extent | 749527 | |
dc.language.iso | eng | |
dc.relation.ispartof | The Journal of Organic Chemistry | en |
dc.subject | QD Chemistry | en |
dc.subject | Organic Chemistry | en |
dc.subject | NDAS | en |
dc.subject.lcc | QD | en |
dc.title | EPR and preparative studies of 5-endo cyclizations of radicals derived from alkenyl NHC-boranes bearing tert-butyl ester substituents | en |
dc.type | Journal article | en |
dc.contributor.institution | University of St Andrews. School of Chemistry | en |
dc.contributor.institution | University of St Andrews. EaSTCHEM | en |
dc.identifier.doi | https://doi.org/10.1021/acs.joc.8b03112 | |
dc.description.status | Peer reviewed | en |
dc.date.embargoedUntil | 2020-01-21 |
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