The dual behaviour of β-vinylporphyrins in the presence of α,α′-dioxothiones

• Published in: New journal of chemistry 2023-11, Vol.47 (44), p.2266-2271
• Main Authors: Dias, Cristina J, Papi, Francesco, Denis, Maxime, Nativi, Cristina, Neves, M. Graça P. M. S, Faustino, M. Amparo F
• Format: Article
• Language: English
• Subjects: Cycloaddition; Diels-Alder reactions; Porphyrins
• ISSN: 1144-0546; 1369-9261
• DOI: 10.1039/d3nj02859c

α,α′-Dioxothiones are very reactive species and can participate in cycloaddition reactions with several compounds. Porphyrins bearing vinyl groups are interesting scaffolds for further functionalization namely by cycloaddition reactions; it is well known that porphyrins can react as either a 2π or 4π component in different cycloaddition approaches, such as hetero Diels-Alder reactions. This study reports for the first time the reactivity of a α,α′-dioxothione in the presence of 5,10,15,20-tetraphenylporphyrin bearing a vinyl group ( 2-VinylTPP ) and of its Zn( ii ) complex ( Zn-VinylTPP ). The results revealed that the reactivity of α,α′-dioxothione as a heterodienophile or as a heterodiene is dependent on the absence or on the presence of Zn( ii ) in the porphyrin inner core. Thus, the free base 2-VinylTPP reacted as a diene affording two diastereomeric chlorins ( 3a and 3b ) that are in a tautomeric equilibrium with porphyrin 4 , and Zn-VinylTPP reacted as a dienophile affording porphyrin 5 and different oxidized products. All the cycloadducts obtained were revealed to be emissive in the red region and be able to produce 1 O 2 . α,α′-Dioxothione react with meso -tetraarylporphyrins bearing vinyl functionalities as a heterodienophiles or as a heterodienes. The dual behaviour is dependent on the absence or on the presence of a metal ion on the porphyrin inner core.