Pyreniporphyrins: Porphyrin Analogues That Incorporate a Polycyclic Aromatic Hydrocarbon Subunit within the Macrocyclic Framework

5 years ago

Pyreniporphyrins: Porphyrin Analogues That Incorporate a Polycyclic Aromatic Hydrocarbon Subunit within the Macrocyclic Framework

Deyaa I. AbuSalim, Timothy D. Lash, Ruixiao Gao

The first examples of porphyrin analogues incorporating pyrene units are reported. Acid-catalyzed condensation of a pyrene dialdehyde with a tripyrrane, followed by oxidation with DDQ, afforded a polycyclic aromatic hydrocarbon (PAH)–porphyrin hybrid in 38% yield. Pyreniporphyrin proved to be devoid of global aromatic character, but upon protonation aromatic mono- and dicationic species were generated. In the proton NMR spectrum for the dication, the internal CH was shifted upfield to approximately +3 ppm. NICS calculations and ACID plots confirmed the diatropic nature of these structures. Pyreniporphyrin reacted with palladium(II) acetate to give excellent yields of a palladium(II) complex that showed weakly diatropic properties. Treatment of the pyrene dialdehyde with phenylmagnesium bromide generated a dicarbinol that reacted with excess pyrrole in the presence of boron trifluoride etherate to give a tripyrrane analogue. Lewis acid catalyzed ring closure with a thiophene dialcohol in 2% ethanol–dichloromethane afforded a tetraphenylthiapyreniporphyrin in 31% yield. This porphyrinoid was nonaromatic in the free-base form but showed significant diatropicity upon protonation. These results demonstrate that PAH–porphyrin hybrids are easily accessible, and this strategy may allow the incorporation of even larger aromatic subunits.

Publisher URL: http://dx.doi.org/10.1021/acs.joc.7b00829

DOI: 10.1021/acs.joc.7b00829