Solvent-free synthesis and structural characterization of azolyl-substituted pyrimidines

Abstract

Base-catalyzed trimerization of N-cyanomethylazoles under pressure and in solvent-free conditions afforded 4-amino-2,6-bis(azol-1-ylmethyl)-5-(azol-1-yl)pyrimidines (1–3) in 33–67% yields. The structures of these compounds was determined by a combination of NMR techniques and X-ray crystallography. The 4-amino groups show a restricted rotation around the C–N bond; the free energy of activation for this process was determined by variable temperature experiments. In the crystal structure of the pyrazol-1-yl derivative, the amino group shows a distorted planar geometry in both independent molecules and acts as a double hydrogen bond donor towards two of the three pyrazole rings, forming ribbons of R₂²(10) rings.