27889-20-9Relevant academic research and scientific papers
Synthesis of fluorosilylenolates, aminosilylenolates, -ethers, and aldol condensates
Büschen, Thomas,Dietz, Wibke,Klingebiel, Uwe,Noltemeyer, Mathias,Schwerdtfeger, Yvonne
experimental part, p. 1358 - 1370 (2008/10/09)
Depending on the reaction conditions, ketones react with n-BuLi, tert-BuLi or lithium diisopropylamide to give enolates or alcoholates. In the reaction of tert-butylmethylketone with n-BuLi followed by fluorosilanes, the fluorosilyl-enolates H2C=C(O-SiFRR′)CMe3 (1-4) and fluorosilylethers Me3C(CH3)(n-C4H 9)C-O-SiFRR′ (5-8) [R, R′ = Me (1, 5); F, CMe3 (2, 6); F, C6H5 (3, 7); F, CHMe2 (4, 8)] are formed. Using tert-butylmethylketone, n-BuLi and (Me3C) 2SiF2, isobutene and the fluorosilyl-enolate of acetaldehyde H2C=CH-O-SiF(CMe3)2 (9) are obtained. Diisopropylketone reacts with Me3CLi and fluorosilanes to give the fluorosilyl-enolates Me2C=C(O-SiFRR′)CHMe2 (10, 11) and -ethers, Me3C(Me2HC)2C-O- SiFRR′ (12, 13) [R, R′ = Me (10, 11); F, CMe3 (12, 13)] whereas only the silylethers R(Me)(C6H5)C-O-SiFRR′ [R, R′, R″ = n-C4H9, Me, Me (14); C 6H5, F, Me (15)] are generated in the reaction of H 3C(C6H5)C=O with lithium-alkyls and fluorosilanes. 1-Di(tert-butyl)fluorosiloxy-1-cyclohexene (16) is the product of the reaction of lithiated cyclohexanone and (Me3C) 2SiF2. A side reaction of the enolate formation is often a condensation releasing water. For that reason, acyclic and cyclic siloxanes may appear as by-products, e. g. disiloxane (17) using (Me3C) 2SiF2, cyclotrisiloxane (Me3C(C 6H5)Si-O)3 (18) using Me3(C 6H5)SiF2, or cyclotetrasiloxane (Me 3CSiF-O)4 (19) using Me3CSiF3 in these reactions. Attempts to prepare the enolate of cyclopentanone in the reaction with lithium diisopropylamide lead to the formation of 2,5-dicyclopentylidenepentanone (20). The 3,5,7-triphenyl-3-methyl-4,6- hexadienephenone (21) is an aldol condensate of Me(C6H 5)CO. Lithium-tert-butylmethylenolate reacts with fluorosilyl-enolates 1-3 or SiF4 to give bis(enolato)silanes, (H 2C=C(CMe3)O-)2SiRR′ [R, R′ = Me (22); F, CMe3 (23); F, C6H5 (24);] and the tris(enolato)silanes (H2C=C(CMe3)O-)3SiR [R = C6H5 (25); F (26)]. Aminosilyl-enolates H 2C=C(O-SiR′R″-NHR)CMe3 are obtained in reactions of fluorosilyl-enolates with lithium amide [27: R= CMe3, R′= Me, R″= Me; 28: R= C6H5, R′= F, R″= CMe3;]. Results of the crystal structure determinations of 17, the cis-isomer of 18, one trans-isomer of 19, the pentanone 20, and the hexadienephenone 21 are reported.
