School of Chemistry, Monash University, PO Box 23, Melbourne, VIC, 3800, Australia.
Research School of Chemistry, Australian National University, Acton, ACT, 2601, Australia.
Chemistry. 2023 Apr 21;29(23):e202300135. doi: 10.1002/chem.202300135. Epub 2023 Mar 16.
The aryl ketones, 9-fluorenone (fluor), 9-xanthenone (xanth) and 9,10-anthraquinone (anth), were reacted with β-diketiminato dimagnesium(I) compounds, [{( Nacnac)Mg} ] ( Nacnac=[HC(MeCNAr) ] , Ar=mesityl (Mes) or 2,6-diisopropylphenyl (Dip)). This gave stable magnesium ketyl complexes which are monomeric, [( Nacnac)(DMAP)Mg(fluor⋅)] (Ar=Mes or Dip, DMAP=4-dimethylaminopyridine) and [( Nacnac)Mg(xanth⋅)(xanth)]; dimeric, [{( Nacnac)Mg(μ-fluor⋅)} ], or tetrameric, [{( Nacnac)Mg(μ-anth⋅)} ]. In contrast, di-2-pyridylketone (OCPy ) is doubly reduced with [{( Nacnac)Mg} ] (Xyl=xylyl) to give a diamagnetic alkoxy/amido complex, [{( Nacnac)Mg} (μ-OCPy )]. 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, [( Nacnac)Mg(OCR -2-phen)] (OCR =xanth, OCPh 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, [{( Nacnac)(THF)Mg} (μ-chalc )] (Ar=Mes or Xyl) and [{( Nacnac)(THF)Mg} (μ-DBA )]. A pinacol coupling reaction between [{( Nacnac)Mg} ] and 2-adamantanone (OAd) yielded [{( Nacnac)(OAd)Mg} (μ-OAd )], presumably via a ketyl intermediate. This study further highlights the utility magnesium(I) compounds have as selective reducing agents in organic transformations.
芳基酮、9-芴酮（氟）、9-氧杂蒽酮（黄）和 9,10-蒽醌（蒽）与β-二酮亚胺二镁（I）化合物[{(Nacnac)Mg}]（Nacnac=[HC(MeCNAr)]，Ar=均三甲苯基（Mes）或 2,6-二异丙基苯基（Dip））反应。这得到了稳定的镁酮基配合物，它们是单体的[(Nacnac)(DMAP)Mg(fluor⋅)]（Ar=Mes 或 Dip，DMAP=4-二甲氨基吡啶）和[(Nacnac)Mg(xanth⋅)(xanth)]；二聚体的[{(Nacnac)Mg(μ-fluor⋅)}]，或四聚体的[{(Nacnac)Mg(μ-anth⋅)}]。相比之下，二吡啶酮（OCPy）与[{(Nacnac)Mg}]（Xyl=二甲苯）反应被双重还原得到顺磁性烷氧基/酰胺配合物[{(Nacnac)Mg}(μ-OCPy)]。这些配合物已通过 X 射线晶体学和三种情况下的电子顺磁共振波谱法进行了表征。镁酮基与菲咯啉（phen）之间的区域选择性 C-C 杂偶联反应生成了烷氧基化合物[(Nacnac)Mg(OCR-2-phen)]（OCR=xanth、OCPh 或 OC(Ph)(2-Me-Ph)）。此外，使用镁（I）还原剂，烯酮、查耳酮（chalc）和二苄基乙二酮（DBA）的同 C-C 偶联反应提供了二镁烯醇化物[{(Nacnac)(THF)Mg}（μ-chalc）]（Ar=Mes 或 Xyl）和[{(Nacnac)(THF)Mg}（μ-DBA）]。[{(Nacnac)Mg}]与 2-金刚烷酮（OAd）之间的频哪醇偶联反应生成[{(Nacnac)(OAd)Mg}（μ-OAd）]，可能是通过酮基中间体。这项研究进一步强调了镁（I）化合物作为有机转化中选择性还原剂的用途。
