Synthesis, Chiroptical Properties, and Absolute Configuration Determination of Phenyl-4-pyridyl-2,5-dipyrimidinylmethane

Abstract

Phenyl-4-pyridyl-2,5-dipyrimidinylmethane (1) has been synthesized in five steps from 5-methylpyrimidine. The structural feature of 1 is the symmetry elements with respect to the 180° rotation of the aryl group along the central C−C bonds. Due to this structural feature, the compound 1 is expected the good crystallinity despite of the asymmetric molecular structure. The optical resolution of 1 was achieved by high performance liquid chromatography using chiral stationary phase (chiral HPLC). The circular dichroism (CD) spectra of the two fractions showed opposite signs. As expected, the X-ray crystallographic analysis was successfully performed for both the racemic and enantiomerically pure crystals of 1, with the nitrogen atoms being unambiguously assigned in both cases. It was concluded the first-eluted fraction in chiral HPLC was determined to be S configuration both by the CD calculation for reproducing the experimental CD spectrum and by the anomalous diffraction of X-ray crystallographic analysis of enantiomerically pure 1.