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Zn‐Mediated Synthesis of 3‐Substituted Indoles Using a Three‐Component Reaction Approach
Author(s) -
Anselmo Daniele,
EscuderoAdán Eduardo C.,
Martínez Belmonte Marta,
Kleij Arjan W.
Publication year - 2012
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201200150
Subject(s) - malononitrile , chemistry , reagent , catalysis , stoichiometry , indole test , lewis acids and bases , combinatorial chemistry , reaction conditions , organic chemistry
Abstract The synthesis of 3‐substituted indoles was investigated through a multicomponent reaction (MCR) approach by using aldehydes, indole and malononitrile as the reagents. The reaction was catalyzed by Lewis acidic Zn(salphen) complexes and their performance was compared with a number of other Zn II structures and M(salphen)s, which showed the Zn(salphen)s to be superior. However, the complex nature of this three‐component reaction (3‐CR) results in substantial byproduct formation that arises from the intermediate benzylidene malononitrile species. The 3‐CR was studied in detail that covered the influence of the base, solvent, reagent stoichiometry and also involved stability studies. The results led to a mechanistic proposal in which the benzylidene malononitrile intermediate plays a central role; it is one of the major species that is formed in most of the catalytic reactions studied. Furthermore, it provided a prelude for the in situ reaction with the malononitrile reagent, which most probably affords a complex mixture of N‐containing heterocycles.