Single step incorporation of carboxylic acid groups in the lower rim of calix[4]arenes: a recyclable catalyst towards assembly of diverse five ring fused acridines

Abstract

This is the first report of an efficient protocol for the incorporation of the –COOH moiety in a single step at the lower rim of calixarene to produce a new calix[4]arene grafted tricarboxylic acid, calix 4a. Generation of this catalyst was confirmed by NMR and HRMS analyses. The efficacy of this compound as an organocatalyst was successfully extended towards the synthesis of an assembly of new diversely substituted five ring fused acridine derivatives.