Direct Synthesis of Chiral Porphyrin Macrocyclic Receptors via Regioselective Nitration

Nitration of tetraphenylporphyrin cage compound <b>1</b>, at −40 °C, leads to the regioselective formation of the chiral mononitro compound <b>2</b> (75% isolated yield) and, at −30 °C, to the achiral <i>syn</i>-dinitro-derivative <b>3</b> and the chiral <i>anti</i>-dinitro derivative <b>4</b> in a diastereomeric ratio of 5:2, which were separated by chromatography (46 and 20% yields, respectively). The structures of the compounds were confirmed by X-ray crystallography