TY - JOUR
T1 - Ketyl Radicals Generated from Magnesium(I) Compounds
T2 - Useful Reagents for C−C Bond Forming Reactions
AU - Rosengarten, Christopher A.
AU - Yuvaraj, K.
AU - Lim, Li Feng
AU - Cox, Nicholas
AU - Jones, Cameron
N1 - Funding Information:
C.J. and N.C. thank the Australian Research Council for funding. Moreover, this material is based upon work supported by the Air Force Office of Scientific Research under award number FA2386‐21‐1‐4048. L.F.L. acknowledges the support of an Australian Government Research Training Program (RTP) International Scholarship. Dr. Jamie Hicks (ANU) is thanked for informative and helpful discussions. Part of this research was undertaken on the MX1 beam line at the Australian Synchrotron, Victoria, Australia. Open Access publishing facilitated by Monash University, as part of the Wiley ‐ Monash University agreement via the Council of Australian University Librarians.
Publisher Copyright:
© 2023 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.
PY - 2023/4/21
Y1 - 2023/4/21
N2 - The aryl ketones, 9-fluorenone (fluor), 9-xanthenone (xanth) and 9,10-anthraquinone (anth), were reacted with β-diketiminato dimagnesium(I) compounds, [{(ArNacnac)Mg}2] (ArNacnac=[HC(MeCNAr)2]−, Ar=mesityl (Mes) or 2,6-diisopropylphenyl (Dip)). This gave stable magnesium ketyl complexes which are monomeric, [(ArNacnac)(DMAP)Mg(fluor⋅)] (Ar=Mes or Dip, DMAP=4-dimethylaminopyridine) and [(MesNacnac)Mg(xanth⋅)(xanth)]; dimeric, [{(MesNacnac)Mg(μ-fluor⋅)}2], or tetrameric, [{(DipNacnac)Mg(μ-anth⋅)}4]. In contrast, di-2-pyridylketone (OCPy2) is doubly reduced with [{(XylNacnac)Mg}2] (Xyl=xylyl) to give a diamagnetic alkoxy/amido complex, [{(XylNacnac)Mg}2(μ-OCPy2)]. These complexes have been characterized by X-ray crystallography, and in three cases, EPR spectroscopy. Regioselective C−C hetero-coupling reactions between magnesium ketyls and phenanthroline (phen) have yielded the alkoxy compounds, [(MesNacnac)Mg(OCR2-2-phen)] (OCR2=xanth, OCPh2 or OC(Ph)(2-Me−Ph)). In addition, homo- C−C couplings of the enones, chalcone (chalc) and dibenziylideneactetone (DBA), using magnesium(I) reducing agents, have afforded dimagnesium enolates, [{(ArNacnac)(THF)Mg}2(μ-chalc2)] (Ar=Mes or Xyl) and [{(DipNacnac)(THF)Mg}2(μ-DBA2)]. A pinacol coupling reaction between [{(DipNacnac)Mg}2] and 2-adamantanone (OAd) yielded [{(DipNacnac)(OAd)Mg}2(μ-OAd2)], presumably via a ketyl intermediate. This study further highlights the utility magnesium(I) compounds have as selective reducing agents in organic transformations.
AB - The aryl ketones, 9-fluorenone (fluor), 9-xanthenone (xanth) and 9,10-anthraquinone (anth), were reacted with β-diketiminato dimagnesium(I) compounds, [{(ArNacnac)Mg}2] (ArNacnac=[HC(MeCNAr)2]−, Ar=mesityl (Mes) or 2,6-diisopropylphenyl (Dip)). This gave stable magnesium ketyl complexes which are monomeric, [(ArNacnac)(DMAP)Mg(fluor⋅)] (Ar=Mes or Dip, DMAP=4-dimethylaminopyridine) and [(MesNacnac)Mg(xanth⋅)(xanth)]; dimeric, [{(MesNacnac)Mg(μ-fluor⋅)}2], or tetrameric, [{(DipNacnac)Mg(μ-anth⋅)}4]. In contrast, di-2-pyridylketone (OCPy2) is doubly reduced with [{(XylNacnac)Mg}2] (Xyl=xylyl) to give a diamagnetic alkoxy/amido complex, [{(XylNacnac)Mg}2(μ-OCPy2)]. These complexes have been characterized by X-ray crystallography, and in three cases, EPR spectroscopy. Regioselective C−C hetero-coupling reactions between magnesium ketyls and phenanthroline (phen) have yielded the alkoxy compounds, [(MesNacnac)Mg(OCR2-2-phen)] (OCR2=xanth, OCPh2 or OC(Ph)(2-Me−Ph)). In addition, homo- C−C couplings of the enones, chalcone (chalc) and dibenziylideneactetone (DBA), using magnesium(I) reducing agents, have afforded dimagnesium enolates, [{(ArNacnac)(THF)Mg}2(μ-chalc2)] (Ar=Mes or Xyl) and [{(DipNacnac)(THF)Mg}2(μ-DBA2)]. A pinacol coupling reaction between [{(DipNacnac)Mg}2] and 2-adamantanone (OAd) yielded [{(DipNacnac)(OAd)Mg}2(μ-OAd2)], presumably via a ketyl intermediate. This study further highlights the utility magnesium(I) compounds have as selective reducing agents in organic transformations.
KW - C−C coupling
KW - ketyl
KW - low oxidation state
KW - magnesium(I)
KW - radical
UR - http://www.scopus.com/inward/record.url?scp=85150016792&partnerID=8YFLogxK
U2 - 10.1002/chem.202300135
DO - 10.1002/chem.202300135
M3 - Article
AN - SCOPUS:85150016792
SN - 1521-3765
VL - 29
JO - Chemistry - A European Journal
JF - Chemistry - A European Journal
IS - 23
M1 - e202300135
ER -