Please use this identifier to cite or link to this item:
https://doi.org/10.1002/ajoc.201300169
DC Field | Value | |
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dc.title | Selective bromination of sp3 C-H bonds by organophotoredox catalysis | |
dc.contributor.author | Kee, C.W. | |
dc.contributor.author | Chan, K.M. | |
dc.contributor.author | Wong, M.W. | |
dc.contributor.author | Tan, C.-H. | |
dc.date.accessioned | 2014-10-16T08:39:50Z | |
dc.date.available | 2014-10-16T08:39:50Z | |
dc.date.issued | 2014 | |
dc.identifier.citation | Kee, C.W., Chan, K.M., Wong, M.W., Tan, C.-H. (2014). Selective bromination of sp3 C-H bonds by organophotoredox catalysis. Asian Journal of Organic Chemistry 3 (4) : 536-544. ScholarBank@NUS Repository. https://doi.org/10.1002/ajoc.201300169 | |
dc.identifier.issn | 21935807 | |
dc.identifier.uri | http://scholarbank.nus.edu.sg/handle/10635/94766 | |
dc.description.abstract | We report that bromination of aliphatic and benzylic sp3 C-H bonds can be achieved with visible light photoredox catalysis by using a low loading of EosinY disodium salt, an inexpensive organic dye, as a photoredox catalyst. The light source is a low-power household lamp and the reaction can be performed without the need of an inert atmosphere and anhydrous solvent. Easy-to-handle CBr4 is the source of bromine and morpholine is necessary for the reaction. Preliminary experimental and computational studies on the mechanism strongly suggest that an N-morpholino radical is responsible for the C-H activation step. This led us to propose that this is a radical relay reaction, in which a longer-lived morpholine radical is generated from a CBr3 radical, which is relatively more transient, by a thermodynamically favorable reaction. Additional evidence for the existence of such an N-radical was obtained from radical trapping experiments. The strong preference of this reaction for electron-rich hydrogen atoms, and the high sensitivity to the steric environment around the C-H bond enables bromination to occur on the relatively stronger C-H bond (as quantified by bond dissociation enthalpy) on the same molecule. The potential for utilizing this reaction to achieve mild and regioselective bromination of sp3 C-H bonds in complex molecules is exemplified by the bromination of (+)-sclareolide and acetate-protected estrone. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. | |
dc.description.uri | http://libproxy1.nus.edu.sg/login?url=http://dx.doi.org/10.1002/ajoc.201300169 | |
dc.source | Scopus | |
dc.subject | Bromination | |
dc.subject | C-H activation | |
dc.subject | Density functional calculations | |
dc.subject | Photoredox catalysis | |
dc.subject | Radical reactions | |
dc.type | Article | |
dc.contributor.department | CHEMISTRY | |
dc.description.doi | 10.1002/ajoc.201300169 | |
dc.description.sourcetitle | Asian Journal of Organic Chemistry | |
dc.description.volume | 3 | |
dc.description.issue | 4 | |
dc.description.page | 536-544 | |
dc.identifier.isiut | 000334789100034 | |
Appears in Collections: | Staff Publications |
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