N-Confused Phlorin-Prodigiosin Chimera: meso-Aryl Oxidation and π-Extension Triggered by Peripheral Coordination

Abstract

An N-confused phlorin isomer bearing a dipyrrin moiety at the α-position of the confused pyrrole ring (1) was synthesized. Pd^II and B^III coordination at the peripheral prodigiosin-like moiety of 1 afforded the corresponding complexes 2 and 3. Reflux of 2 in triethylamine (TEA) converted the meso-phenyl into the Pd^II -coordinating phenoxy group to afford 4. Under the same reaction conditions, TEA was linked to the α-position of the dipyrrin unit in 3 as an N,N-diethylaminovinyl group to afford 5. Furthermore, peripheral coordination of B^III in 3 and 5 improved the planarity of the phlorin macrocycle and thus facilitated the coordination of Ag^III at the inner cavity to afford 3-Ag and 5-Ag, respectively. These results provide an effective approach for developing unique porphyrinoids through peripheral coordination.

Keywords: conjugation; coordination chemistry; oxidation; palladium; porphyrinoids.