Synthesis of Functionalized Indoles with an α-Stereogenic Ketone Moiety Through an Enantioselective Friedel-Crafts Alkylation with (<i>E</i>)-1,4-Diaryl-2-butene-1,4-diones
作者:Gonzalo Blay、Isabel Fernández、Alicia Monleón、M. Carmen Muñoz、José R. Pedro、Carlos Vila
DOI:10.1002/adsc.200900357
日期:2009.10
temperature, with good yields and ee up to 94%. Hafnium(IV) was found to be a more effective Lewis acid than other frequently used metal ions such as titanium(IV) or zirconium(IV). Unlike the enantioselective Friedel–Crafts alkylation of indoles with α,β-unsaturated compounds where the stereogenic center is generated in the β-position to a carbonyl group, the Friedel–Crafts alkylation with 2-butene-1
基于BINOL的配体与叔丁醇ha的手性配合物在室温下催化具有(E)-1,4-二芳基-2-丁烯-1,4-二酮的吲哚的对映选择性Friedel-Crafts烷基化反应,具有良好的收率和ee高达94%。发现than(IV)比其他常用的金属离子,例如钛(IV)或锆(IV)更有效的路易斯酸。与α,β-不饱和化合物使吲哚的对映选择性Friedel-Crafts烷基化(立体位中心在羰基的β位产生)不同,此处所述的2-2-丁烯-1,4-二酮的Friedel-Crafts烷基化生成相对于羰基之一的α-立体异构中心。这可以看作是正常反应模式或能量颠倒的结果。带有(E的吲哚的对映选择性Friedel-Crafts烷基化还报道了使用锆(IV)-BINOL催化剂的)-4-氧代-4-苯基丁烯酸酯。该反应在酮羰基的β位的碳上区域选择性地发生,从而生成α-酯立体异构中心。