Asymmetric Synthesis of Hydrocarbazoles Catalyzed by an Octahedral Chiral-at-Rhodium Lewis Acid
作者:Yong Huang、Liangliang Song、Lei Gong、Eric Meggers
DOI:10.1002/asia.201500764
日期:2015.12
bis‐cyclometalated chiral‐at‐metal rhodium complex catalyzes the Diels–Alder reaction between N‐Boc‐protected 3‐vinylindoles (Boc=tert‐butyloxycarbonyl) and β‐carboxylic ester‐substituted α,β‐unsaturated 2‐acyl imidazoles with good‐to‐excellent regioselectivity (up to 99:1) and excellent diastereoselectivity (>50:1 d.r.) as well as enantioselectivity (92–99 % ee) under optimized conditions. The rhodium catalyst
双环金属化的手性金属铑配合物催化N -Boc保护的3-乙烯基吲哚(Boc =叔-丁氧基羰基)与β-羧酸酯取代的α,β-不饱和2-酰基咪唑之间的Diels-Alder反应在最佳条件下,区域选择性很好(高达99:1),非对映选择性(> 50:1 dr)和对映选择性(92–99%ee)。铑催化剂起手性路易斯酸的作用,通过两点结合来活化2-酰基咪唑二烯亲和体,并否决了未催化反应的优选区域选择性。