Synthesis of 7-Substituted Indoles as Potential Ligand Precursors

Abstract

Some 7-(pyridin-2′'-yl)- and 7-(pyrazol-1′-yl)-indole-2-carboxylic esters (14)-(16) and the related acids (17) and (18) have been synthesized through the Fischer indole cyclizations of the ethyl pyruvate hydrazones (9)-(12), which were in turn derived from the ortho -functionalized anilines (5)-(8) by diazotization and coupling with ethyl 2-methyl-3-oxobutanoate (the Japp-Klingemann reaction).