Intramolecular Alkylation of α-Diimine Ligands Giving AmidoImino and Diamido Scandium and Yttrium Complexes as Catalysts for Intramolecular Hydroamination/Cyclization

Treatment of alkyl complexes M(CH2SiMe3)3(THF)2 (1a: M = Sc; 1b: M = Y) with α-diimine ligands, N,N′-bis(2,6-dimethylphenyl)-1,4-diaza-1,3-butadiene (2a) and N,N′-bis(2,6-diisopropylphenyl)-1,4-diaza-1,3-butadiene (2b), afforded the corresponding amido−imino complexes M(CH2SiMe3)2(2,6-R2Ph-DAB-CH2SiMe3)(THF) (3a: M = Sc, R = Me; 3b: M = Sc, R = iPr; 4a: M = Y, R = Me; 4b: M = Y, R = iPr) by selective monoalkylation of one of two CN bonds of the ligands followed by intramolecular H migration, while in the reactions with a less bulky α-diimine ligand, N,N′-bis(4-methylphenyl)-1,4-diaza-1,3-butadiene (2c), complex 1a gave an diamido complex ScCH2SiMe3(4-MePh-DAB-(CH2SiMe3)2)(THF)2 (5c) as a product of the double alkylation. Upon heating a hexane solution of 3b, intramolecular activation of a CH bond of an isopropyl group of the ligand proceeded to give a scandium monoalkyl complex ScCH2SiMe3(CH2C2H4-6-iPrPh-2,6-iPr2Ph-DAB-CH2SiMe3)(THF) (6b). Among them, amidoimino complexes of yttrium became catalysts for intramolecular hydroamination/cyclization of 2,2-dimethyl-4-pentenylamine at room temperature.

将烷基配合物M(CH2SiMe3)3(THF)2（1a：M=钪（Sc）；1b：M=钇（Y））与α-二亚胺配体（α-diimine ligands）N,N'-双(2,6-二甲基苯基)-1,4-二氮杂-1,3-丁二烯（2a）以及N,N'-双(2,6-二异丙基苯基)-1,4-二氮杂-1,3-丁二烯（2b）进行反应，其中THF为四氢呋喃（tetrahydrofuran），可通过对配体两条C=N双键中的一条进行选择性单烷基化并伴随分子内氢迁移，得到相应的酰胺亚胺基配合物M(CH2SiMe3)2(2,6-R2Ph-DAB-CH2SiMe3)(THF)（3a：M=Sc，R=甲基（methyl, Me）；3b：M=Sc，R=异丙基（isopropyl, iPr）；4a：M=Y，R=Me；4b：M=Y，R=iPr）；而当使用位阻更小的α-二亚胺配体（α-diimine ligands）N,N'-双(4-甲基苯基)-1,4-二氮杂-1,3-丁二烯（2c）进行反应时，配合物1a则生成二酰胺基配合物ScCH2SiMe3(4-MePh-DAB-(CH2SiMe3)2)(THF)2（5c），该产物为双烷基化反应的结果；将3b的己烷溶液加热后，配体异丙基的C-H键发生分子内活化，得到钪单烷基配合物ScCH2SiMe3(CH2C2H4-6-iPrPh-2,6-iPr2Ph-DAB-CH2SiMe3)(THF)（6b）；其中，钇的酰胺亚胺基配合物可作为催化剂，在室温下催化2,2-二甲基-4-戊烯胺的分子内氢胺化/环化反应。