An Efficient Synthesis of Porphyrins with Different meso Substituents that Avoids Scrambling in Aqueous Media. Issue 4 (21st November 2014)

• Record Type: Journal Article
• Authors: Nowak‐Król, Agnieszka; Plamont, Rémi; Canard, Gabriel; Edzang, Judicaelle Andeme; Gryko, Daniel T.; Balaban, Teodor Silviu
• Is Part Of: Chemistry. Volume 21:Issue 4(2015)
• Page Start: 1488
• Page End: 1498
• Publication Date: 2014-11-21
• Subjects: Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201403677
• Languages: English
• ISSNs: 0947-6539

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>We have developed new conditions that afford regioisomerically pure <italic>trans</italic>‐A<sub>2</sub>B<sub>2</sub>‐, A<sub>3</sub>B‐, and <italic>trans</italic>‐AB<sub>2</sub>C‐porphyrins bearing aryl and arylethynyl substituents. The porphyrins were prepared by the acid‐catalyzed condensation of dipyrromethanes with aldehydes followed by oxidation with <italic>p</italic>‐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<sub>2</sub>O 4:1, [DPM]=4 m<sc>M</sc>, [aldehyde]=4 m<sc>M</sc>, [HCl]=38 m<sc>M</sc>, 16 h; for arylethynyl aldehydes: THF/H<sub>2</sub>O 2:1, [DPM]=13 m<sc>M</sc>, [aldehyde]=13 m<sc>M</sc>, [HCl]=150 m<sc>M</sc>, 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 <italic>trans</italic>‐A<sub>2</sub>B<sub>2</sub>‐, A<sub>3</sub>B‐, and <italic>trans</italic>‐AB<sub>2</sub>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.</p> </abstract>