Synthesis of Pentafluorophenylmethylamines via Silicon Mannich Reaction

Abstract

[reaction: see text] The three-component coupling of aldehydes, secondary amines, and methoxytris(pentafluorophenyl)silane, MeOSi(C(6)F(5))(3), affording pentafluorophenylmethylamines has been described. The generation of the five-coordinate silicate intermediate is believed to be the key feature responsible for the efficiency of the reaction.

Reactions of salicylaldehyde with tris(pentaf luorophenyl)silanes and secondary amines

“…As noted earlier, 5 unlike MeOSi(C 6 F 5 ) 3 , silanes hav ing only methyl and C 6 F 5 groups at the Si atom (com pounds with the general formula Me n Si(C 6 F 5 ) 4-n ; n = 1, 2, and 3) are inefficient reagents for three compo nent coupling with benzaldehyde and secondary amines. We assumed that introduction into an aldehyde molecule of an adjacent hydroxy group capable of binding to a silyl reagent can promote an alternative mechanism, which in turn would allow other C 6 F 5 containing silanes to be used.…”

Synthesis and structures of tris(pentafluorophenyl)silylamines

“…The key feature of these compounds is the high Lewis acidity of the silicon atom due to the presence of three electron withdrawing pentafluorophenyl substituents. In particu lar, ROSi(C 6 F 5 ) 3 3, 4 and MeSi(C 6 F 5 ) 3 6,7 proved to be con venient reagents in the transfer of the C 6 F 5 group to iminium carbocations. In addition, the crystal structures of O and C tris(pentafluorophenyl)silyl derivatives are characterized by interesting features, in particular, by the presence of stacking interactions involving the C 6 F 5 groups and very short Si-O and Si-C bonds.…”

“…Silanes, in which the (C 6 F 5 ) 3 Si fragment is bound to the oxygen 1-4 or car bon 5-7 atom, have received considerable attention. The key feature of these compounds is the high Lewis acidity of the silicon atom due to the presence of three electron withdrawing pentafluorophenyl substituents.…”

“…In addition, the crystal structures of O and C tris(pentafluorophenyl)silyl derivatives are characterized by interesting features, in particular, by the presence of stacking interactions involving the C 6 F 5 groups and very short Si-O and Si-C bonds. [1][2][3][4][5] In this connection, it was of interest to study analogous derivatives with the Si-N bond. Only one representative of tris(pentafluorophenyl)silylamines, Me 2 NSi(C 6 F 5 ) 3 , was mentioned in the literature, but it was synthesized with the use of strongly basic anionic reagents by the reaction of lithium dimethylamide with (C 6 F 5 ) 3 SiCl (1) or by the reaction of pentafluorophenyllithium with Cl 3 SiNMe 2 .…”

“…[1][2][3][4][5] In this connection, it was of interest to study analogous derivatives with the Si-N bond. Only one representative of tris(pentafluorophenyl)silylamines, Me 2 NSi(C 6 F 5 ) 3 , was mentioned in the literature, but it was synthesized with the use of strongly basic anionic reagents by the reaction of lithium dimethylamide with (C 6 F 5 ) 3 SiCl (1) or by the reaction of pentafluorophenyllithium with Cl 3 SiNMe 2 . 8 In the present study, we developed a simpler proce dure for the synthesis of compounds containing the (C 6 F 5 ) 3 Si-N fragment based on the reaction of neutral nitrogen containing precursors, such as amines and imi nes, with silylating reagents.…”