An asymmetric Friedel–Craftsalkylation of indoles with nitroacrylates catalyzed by chiral (4R,5S)-DiPh-BOX (L1)–Cu(OTf)2 complex (10 mol %) has been developed. The reactions provide tryptophan nitro-precursors in moderate diastereoselectivities (anti/syn up to 72:28) and good to excellent enantioselectivities (up to 99% ee). The alkylation products could be easily reduced to optically active tryptophan
已开发出手性(4 R,5 S)-DiPh-BOX(L1)-Cu(OTf)2络合物(10 mol%)催化的吲哚与硝基丙烯酸酯的吲哚不对称弗里德-克拉夫茨烷基化反应。该反应以中等非对映选择性提供色氨酸硝基前体(抗/合成至72:28),对映选择性良好(至99%ee)。烷基化产物可以很容易地还原为具有Zn / H +的旋光色氨酸类似物。