Formation of a sixteen-membered ring by condensation of N, N'-dimesityl-propane-1,3-diamine with triethyl orthoformate and ammonium tetrafluoroborate

Cyclocondensation of N,N'-dimesityl-propane-1,3-diamine with triethyl orthoformate and ammonium tetrafluoroborate gave as the major product macrocycle (2) under neat conditions and 1,3-dimesityl-3,4,5,6,-tetrahydro-pyrimidin-1-ium tetrafluoroborate with ethanol as the solvent. The structures of the two ring systems were confirmed by X-Ray diffraction analysis.