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Synthesis and characterization of salen ‐type ligands functionalized with pyrrole derivative pendant arms
Author(s) -
Andrade Mariana,
Sousa Carla,
Enrique Borges José,
Freire Cristina
Publication year - 2005
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.924
Subject(s) - chemistry , schiff base , acylation , pyrrole , imine , derivative (finance) , polymer chemistry , ligand (biochemistry) , carboxylic acid , medicinal chemistry , condensation reaction , organic chemistry , catalysis , biochemistry , receptor , financial economics , economics
Several salen ‐type ligands functionalized with two pyrrole derivative pendant arms were prepared. These Schiff base ligands, which differ in the imine bridge, were prepared by a multi‐step procedure that includes (i) synthesis of 3‐pyrrol‐1‐ylpropanoic acid, (ii) transformation of the latter compound into the mixed carboxylic–carbonic anhydride (MCCA) intermediate followed by reaction with 2,3‐dihydroxybenzaldehyde to give (3‐formyl‐2‐hydroxyphenyl) 3‐(pyrrol‐1‐yl)propanoate and finally (iii) Schiff condensation of the different 1,2‐diamines with (3‐formyl‐2‐hydroxyphenyl) 3‐(pyrrol‐1‐yl)propanoate. The key step in the Schiff base ligand preparation is the functionalization of the 2,3‐dihydroxybenzaldehyde at the C‐3 hydroxyl group without protection of the C‐2 hydroxyl group, by a regiospecific acylation of the ortho ‐hydroxyl group via esterification with the mixed carboxylic–carbonic anhydride of 3‐pyrrol‐1‐ylpropanoic acid. The compounds were characterized by elemental analyses, 1 H and 13 C NMR spectroscopy, mass spectrometry and FTIR and UV–visible spectrophotometry. Copyright © 2005 John Wiley & Sons, Ltd.