Enantioselective Synthesis of Triarylmethanes by Chiral Imidodiphosphoric Acids Catalyzed Friedel–Crafts Reactions
摘要:
The first enantioselective synthesis of pyrrolyl-substituted triarylmethanes has been accomplished using a novel imidodiphosphoric acid catalyst, which is derived from two (R)BINOL frameworks with different 3,3'-substituents. This strategy was also expanded to the synthesis of bis(indolyl)-substituted triarylmethanes with high enantioselectivities, which could only be obtained with moderate ee values in previous reports. These two efficient Friedel-Crafts alkylation processes feature low catalyst loading, broad functional group compatibilities, and the potential to provide practical pathways for the synthesis of enantioenriched bioactive triarylmethanes.
Lewis Acid Catalyzed Intramolecular Direct Ene Reaction of Indoles
作者:Bo Han、You-Cai Xiao、Yuan Yao、Ying-Chun Chen
DOI:10.1002/anie.201005296
日期:2010.12.27
How to fuse heterocycles: The direct enamine–imine isomerization of indoles and subsequent intramolecular imino‐ene has been observed under Lewisacidcatalysis. This unique reaction occurred for indoles that contain a tethered olefin functionality, and led to fused indoline heterocycles with excellent diastereocontrol (see scheme).
The catalytic direct dehydrative coupling of an alkene with an alcohol is one of the most straightforward and green strategies for the formation of Csp2−Csp2 bonds. However, previously reported studies have only dealt with achiral reactions. Here, we describe chiral Brønsted acid‐catalyzed direct catalyticasymmetric dehydrative coupling reactions of 3‐vinylindoles and 3‐indolylmethanols. Various structurally