Synthesis of novel intermediates for cyanine dyes by the quaternization of N-heterocycles with acrylamide and N-alkyl acrylamides

The preparation of several novel important heterocyclic N-(2-carbamoyl-ethyl) quaternary salts by 1,4-addition of an appropriate N-heterocyclic base to acrylamide or N-alkyl acrylamides under different reaction conditions in the presence of hydrochloric, hydrobromic or perchloric acid is described. The products have an activated group at 2- or 4-position and are typical precursors of different types of cyanine dyes. The products were characterized by 1H NMR, IR spectra, HPLC-MS spectrometry and elemental analysis.