Base-promoted three-component cascade approach to unsymmetrical bis(indolyl)methanes
作者:Mohit L. Deb、Bhaskar Deka、Prakash J. Saikia、Pranjal K. Baruah
DOI:10.1016/j.tetlet.2017.04.032
日期:2017.5
base-catalyzed reaction of two different indoles with aldehydes under heating to produce unsymmetrical bis(indolyl)methanes (BIMs), in which one of the indole ring must be N-substituted. Mixture of EtOH-H2O is used as solvent. The reaction did not give symmetrical BIMs of N-substituted indoles or N–H indoles. However, traces of latter were formed in few cases, especially when electron-rich aldehydes were used
An efficient and expedient approach for the synthesis of unsymmetrical 3,3′-Bis-indolylmethanes via silica gel-mediated Friedel-Craftsalkylation of 3-indolylmethanols with diverse indoles is described. The synthetic utility of this transformation was demonstrated by reusing silica gel up to 10 times without apparent loss of reactivity .
Jnsymmetrical arylbis(3-indolyl)methanes have been synthesized via a Bronsted acid catalyzed Friedel-Crafts alkylation of α-(3-indolyl)benzylamines with N-methylindole. With 5 mol% of the catalyst, the reaction proceeds smoothly under mild conditions, affording the unsymmetrical triarylmethanes in excellent yields (up to 98%).