Synthesis of Functional <i>m</i><i>eso</i>-Aryl Porphomonomethenes and Porphodimethenes:  Application to the Preparation of a Chiral Calix[4]phyrin Dimer

Reaction of 5,5-dimethyldipyrromethane (<b>1</b>) with electron-deficient aryl aldehydes in the presence of BF<sub>3</sub>−Et<sub>2</sub>O and NH<sub>4</sub>Cl in propionitrile constitutes efficient, easy access to unprecedented, functional porphomonomethenes together with the expected porphodimethenes (calix[4]phyrins). Alternatively, when the reaction was carried out in CH<sub>2</sub>Cl<sub>2</sub> in the presence of an acid and Florisil, the expected bis-arylcalix[4]phyrin was isolated in 41% yield, while no scrambled macrocycle was detected. After reduction of the nitro function, porphomonomethene <b>9</b> was efficiently condensed with the binaphthyl diacyl chloride (<b>10</b>) leading to the first chiral calix[4]phyrin dimer (<b>11</b>) that exhibits a moderate enantiorecognition toward the enantiomers of malic acid.