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An Efficient Synthesis of Porphyrins with Different meso Substituents that Avoids Scrambling in Aqueous Media
Author(s) -
NowakKról Agnieszka,
Plamont Rémi,
Canard Gabriel,
Edzang Judicaelle Andeme,
Gryko Daniel T.,
Balaban Teodor Silviu
Publication year - 2015
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201403677
Subject(s) - chemistry , aldehyde , porphyrin , condensation , aqueous solution , aqueous medium , solvent , condensation reaction , singlet state , indigo , medicinal chemistry , catalysis , organic chemistry , art , physics , nuclear physics , visual arts , thermodynamics , excited state
We have developed new conditions that afford regioisomerically pure trans ‐A 2 B 2 ‐, A 3 B‐, and trans ‐AB 2 C‐porphyrins bearing aryl and arylethynyl substituents. The porphyrins were prepared by the acid‐catalyzed condensation of dipyrromethanes with aldehydes followed by oxidation with p ‐chloranil or 2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone (DDQ). Optimal conditions for the condensation were identified after examining various reaction parameters such as solvent composition, acid concentration, and reaction time. The conditions identified (for aromatic aldehydes: EtOH/H 2 O 4:1, [DPM]=4 m M , [aldehyde]=4 m M , [HCl]=38 m M , 16 h; for arylethynyl aldehydes: THF/H 2 O 2:1, [DPM]=13 m M , [aldehyde]=13 m M , [HCl]=150 m M , 3 h) resulted in the formation of porphyrins in yields of 9–38 % without detectable scrambling. This synthesis is compatible with diverse functionalities such as ester or nitrile. In total, 20 new trans ‐A 2 B 2 ‐, A 3 B‐, and trans ‐AB 2 C‐porphyrins were prepared. The scope and limitations of the two sets of reaction conditions have been explored. The methodological advantage of this approach is its straightforward access to building blocks and the formation of the porphyrin core in higher yields than by any other methodology and by using environmentally benign and nonhazardous chemicals.