名称:
                                Enhanced efficiency of recyclable C3-symmetric cinchonine-squaramides in the asymmetric Friedel–Crafts reaction of indoles with alkyl trifluoropyruvate
                             
                            
                                摘要:
                                The highly enantioselective Friedel-Crafts reaction of indoles with trifluoropyruvate catalyzed by a C-3-symmetric cinchonine-squaramide is reported. A wide variety of trifluoromethylated indole derivatives were obtained in high yields and with excellent enantioselectivities (99% and up to > 99% ee). Moreover the C-3 catalyst can be easily recovered and was used five times. (C) 2012 Elsevier Ltd. All rights reserved.
                             
                                                            
                                    DOI:
                                    10.1016/j.tetasy.2012.08.015