Crystallographic characterisation of organolithium and organomagnesium intermediates in reactions of aldehydes and ketones

Jennifer R. Lynch, Alan R. Kennedy, Jim Barker, Jacqueline Reid, Robert E. Mulvey

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4 Citations (Scopus)
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We report reactions of LiNacNac and NacNacMg(TMP) with common organic substrates (TMP=2,2,6,6-tetramethylpiperidide). Using bulky β-diketiminate compound NacNac (Me, Dipp), we have trapped metalated intermediates amenable to X-ray crystallographic study. LiNacNac and acetone produced the NacNac-free hexameric diacetone alkoxide [{LiO(MeC(=O)CH 2C(Me) 2} 6]; whereas pinacolone gave the simple monomeric donor–acceptor complex [Li{(MeCN-2,6- iPr 2C 6H 3) 2CH}{O=C(Me) tBu}]. Benzaldehyde produced dimeric [Li{(MeCN-2,6- iPr 2C 6H 3) 2CC(=O)Ph}{O=C(Ph)OCH 2Ph}] 2, where one benzaldehyde molecule has inserted in to the γ-carbon position of the NacNac ligand, with a molecule of benzyl benzoate derived from a Tishchenko reaction of the aldehyde acting as a terminal donor to lithium. Tetranuclear, mixed dimer [{LiO(MeCN-2,6- iPr 2C 6H 3) 2CH-CH(Ph)} 2{LiO(PhC(=O)} 2] containing the same modified NacNac ligand was the fortuitous product from repeating the reaction of LiNacNac and benzaldehyde in a solution presumably contaminated with benzoic acid. Combining NacNacMg(TMP) with pinacolone affords monomeric heteroleptic [Mg{(MeCN-2,6- iPr 2C 6H 3) 2CH}{OC( tBu)(Me)CH 2C(=O) tBu}] with an aldolate constituting the second anion. Completing the set is dimeric [Mg{(MeCN-2,6- iPr 2C 6H 3) 2CH}{O(C=CH 2)Ph} 2], where the enolate derived from acetophenone bridges the magnesium centres.

Original languageEnglish
Article numbere202200082
Number of pages15
JournalHelvetica Chimica Acta
Issue number9
Early online date16 Aug 2022
Publication statusPublished - Sept 2022


  • aldehydes
  • ketones
  • lithium
  • magnesium
  • metalation
  • structure elucidation
  • β-diketiminates


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