Reaction of α-chloroalkyl ketones with 1,3-dinitrobenzenes provides 2,4-dinitrobenzyl
ketones which when reduced with tin(II) chloride form 6-nitro derivatives of 1-hydroxyindoles.
An alternative approach is the condensation of 2,4- and 2,6-dinitrotoluenes with diethyl
oxalate or ethyl trifluoroacetate provides dinitrobenzyl ketones which leads after
reduction with tin(II) chloride to nitro derivatives of 1-hydroxyindol-2-carboxylates
or 1-hydroxy-2-(trifluoromethyl)indoles, respectively.
Key words
indoles - acylation - reduction - nucleophilic aromatic substitution - tin - ketones