768-66-1Relevant articles and documents
Contrasting reactivity of mono- versus Bis-2,2,6,6-tetramethylpiperidide lithium aluminates towards polydentate lewis bases: Co-complexation versus deprotonation
Campbell, Ross,Crosbie, Elaine,Kennedy, Alan R.,Mulvey, Robert E.,Naismith, Rachael A.,Robertson, Stuart D.
, p. 1189 - 1201 (2013)
Two closely related lithium alkylaluminium amides LiAl(TMP)2iBu2 and LiAl(TMP)iBu3 (TMP: 2,2,6,6-tetramethylpiperidide) have been compared in their reactivity towards six polydentate Lewis bases containing either N or O donor atoms or a mixed N,O donor set. Seven of the twelve potential organometallic products of these reactions, which were carried out in hexane solution, have been crystallographically characterised. Three of these structures, [Li(-Me2NCH2CHCH2CH2CHO)(-TMP)Al(iBu)2], [Li(-Me2NCH2CH2OCH2)(-TMP)Al(iBu)2], and [Li(-Me2NCH2CH2OCHCH2NMe2)(-TMP)Al(iBu)2] reveal that the bis-amide LiAl(TMP)2iBu2 deprotonates (aluminates) the multifunctional Lewis base selectively at the carbon atom adjacent to oxygen with the anion generated captured by the residue of the base. In contrast, the mono-amide LiAl(TMP)iBu3 in general fails to deprotonate the Lewis bases but instead forms co-complexes with them as evidenced by the molecular structures of [Me2NCH2CHCH2CH2CH2O·Li(-iBu)(-TMP)Al(iBu)2], [Me2NCH2CH2OMe·Li(- iBu)(-TMP)Al(iBu)2], and [MeOCH2CH2OMe·Li(-iBu)(-TMP)Al(iBu)2]. Providing an exception to this pattern, the mono-amide reagent deprotonates chiral R,R,-N,N,N′,N′-tetramethylcyclohexanediamine to afford [Li(-CH2NMeC6H10NMe2)2Al(iBu)2], the final complex to be crystallographically characterised. All new products have been spectroscopically characterised through 1H, 7 Li, and 13C NMR studies. Reaction mixtures have also been quenched with D2O and analysed by 2D NMR spectroscopy to ascertain the full metallation versus co-complexation picture taking place in solution.
Reactions of a stable phosphinyl radical with stable aminoxyl radicals
Ishida, Shintaro,Hirakawa, Fumiya,Iwamoto, Takeaki
, p. 94 - 96 (2015)
Reaction of stable phosphinyl radical 1a with AZADO gave aminoxyphosphine 3 as the primary product by selective radical coupling at 140 °C. Compound 3 decomposed to phosphorane 4, silyl phosphinate 5, and aminophosphine 6 at room temperature. The molecular structures of 4-6 were determined by X-ray structural analysis. The homolytic N-O bond cleavage of 3 and the subsequent silyl migration of the resulting phosphinoyl radical 7 would be key steps in the reaction.
A large-scale low-cost access to the lithium 2,2,6,6-tetramethylpiperidide precursor
Kampmann, Detlef,Stuhlmueller, Georg,Simon, Roger,Cottet, Fabrice,Leroux, Frederic,Schlosser, Manfred
, p. 1028 - 1029 (2005)
Wolff-Kishner-Huang reduction of the cheap 2,2,6,6-tetramethyl-4- piperidinone (2) provides the expensive 2,2,6,6-tetramethylpiperidine (1), the precursor to lithium 2,2,6,6-tetramethylpiperidide, in high yield. As specified in the detailed protocol, the reaction can be conveniently carried out on a >10 mol laboratory scale. Georg Thieme Verlag Stuttgart.
Copper-Catalyzed Cascade N-Dealkylation/N-Methyl Oxidation of Aromatic Amines by Using TEMPO and Oxygen as Oxidants
Li, Dianjun,Wang, Shihaozhi,Yang, Jiale,Yang, Jinhui
supporting information, p. 6768 - 6772 (2021/12/31)
A novel tandem N-dealkylation and N-methyl aerobic oxidation of tertiary aromatic amines to N-arylformamides using copper and TEMPO has been developed. This methodology suggested an alternative synthetic route from N-methylarylamines to N-arylformamides.
Catalytic CO2 hydrosilylation with [Mn(CO)5Br] under mild reaction conditions
García, Juventino J.,González, Tania
, (2021/06/07)
Carbon dioxide hydrosilylation with earth-abundant transition-metal catalysts is an attractive alternative for the design of greener and cost-effective synthetic strategies. Herein, simple [Mn(CO)5Br] is an efficient precatalyst in the hydrosilylation of carbon dioxide with Et3SiH under mild reaction conditions. Using THF as a solvent, triethylsilylformate Et3SiCH(O)O was obtained in 67% yield after 1 h at 50 °C and 4 bar of CO2 pressure. The selectivity of the reaction was tuned by changing the solvent to a mixture of THF and toluene producing bis(triethylsilyl)acetal (Et3SiO)2CH2 in 86% yield. The CO2 hydrosilylation was also effective at room temperature and atmospheric pressure using either THF or the mixture THF/toluene as the solvent resulting in high Et3SiH conversion (92%–99%) but with a decrease in the selectivity. Radical trapping experiments indicated the participation of radical species in the catalytic mechanism. To the best of our knowledge, this is the first report on CO2 hydrosilylation catalyzed by transition-metal radical intermediates.