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 - 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
SN - 0947-6539
VL - 29
JO - Chemistry - A European Journal
JF - Chemistry - A European Journal
IS - 23
M1 - e202300135
ER -