Pyridine‐Fused Bis(Norcorrole) through Hantzsch‐Type Cyclization: Enhancement of Antiaromaticity by an Aromatic Bridge. Issue 36 (31st July 2017) - Li, Xiaofang
Abstract: A non‐catalytic condensation of Ni II β‐aminonorcorrole with aryl aldehydes is shown to produce a family of pyrromethane dimers that undergo deaminative cyclization to yield pyridine‐fused bis(norcorrole)s comprising two antiaromatic macrocycles communicating by an aromatic moiety. The new compounds were characterized by spectroscopic, structural, and electrochemical methods supported by DFT calculations, all of which revealed unexpected antiaromaticity enhancement in the fused system. Abstract : Peculiar arithmetic : π Electrons are hard to sum up in the ambiguously conjugated pyridine‐fused bis(norcorrolatonickel). The juxtaposition of two antiaromatic porphyrinoid units with the aromatic pyridine centerpiece produces a system with enhanced antiaromaticity, which is favored over global aromatic conjugation.