126404-06-6Relevant articles and documents
On the Role of Lewis Acid Catalysts and Solvents in the Fischer Indole Synthesis
Prochazka, Michal P.,Carlson, Rolf
, p. 651 - 659 (2007/10/02)
The influence of the Lewis acid catalyst and solvent on the Fischer indole reaction has been studied with regard to the distribution of indole isomers in the reaction of phenylhydrazones derived from unsymmetrical ketones.Five ketones, ten solvents and twelve Lewis acids were studied.A multivariate experimental design based on the principal pproperties of the reactants was used to select test systems (substrate, Lewis acid, solvent).A total of 296 of different systems were studied, of which 162 afforded indoles.Analysis of how the properties of these systems are related to the distribution of isomeric indoles was done by PLS modeling.A three-components model was significant according to cross validation and described 87percent of the variance of the isomer distribution.The model showed that the structure of the phenylhydrazone has a dominant influence on isomer distribution; that solvent properties are only wealky involved; and that the properties of the Lewis acid catalyst does not exert any systematic influence on the regioselectivity of the Fischer indole reaction.
