In tandem: A divergent and enantioselectiveapproach to 2,3‐disubstitutedindolines was developed throughconsecutiveBrønstedacid/Pd‐complex‐promotedtandemreactions from simple 2‐substituted indoles and aldehydes in one operation to give up to 98 % ee (see scheme; R1=H, F, or Me; R2=alkyl; R3=aryl or alkyl). Three Brønstedacidpromoted steps and two Pd‐catalyzed hydrogenation steps were involved
串联:通过一次简单的2-取代的吲哚和醛类的连续Brønsted酸/ Pd-络合物促进的串联反应,开发了一种对2,3-二取代的二氢吲哚的发散和对映选择性的方法,使ee高达98% (参见方案) ; R 1= H,F或Me; R 2=烷基; R 3=芳基或烷基)。此过程涉及三个Brønsted酸促进步骤和两个Pd催化的氢化步骤。
Chiral 2,3-Disubstituted Indolines from Indoles and Aldehydes by Organocatalyzed Tandem Synthesis Involving Reduction by Trichlorosilane
作者:Lin Chen、Chao Wang、Li Zhou、Jian Sun
DOI:10.1002/adsc.201301133
日期:2014.7.7
The organocatalytic trichlorosilanereduction system has been successfully utilized to develop a multi‐step tandem approach for the easy preparation of chiral 2‐methyl‐3‐alkylindolines starting from simple 2‐methylindoles and aldehydes. A broad range of chiral 2‐methyl‐3‐alkylindoline products was obtained with high yields and enantioselectivities and excellent stereoselectivities by this approach
A series of 2-substituted 3-(toluenesulfonamidoalkyl)indoles was synthesized by application of (EtO)2POH or iodine as the catalyst, and was hydrogenated using chiral Pd catalyst, giving the 2,3-disubstituted indolines with up to 97% ee.