Synthesis of functionalized chromene and spirochromenes using l -proline-melamine as highly efficient and recyclable homogeneous catalyst at room temperature
commercially cheap l-proline and melamine for the synthesis of chromenes and spirochromenes (spirooxindoles) via multicomponent reactions at room temperature. Systematic studies were conducted in order to achieve desired reactivity and recyclability of the catalyst using various α-amino acids and aromatic amines as donor-acceptor pairs. Among the screened combinations, l-proline and melamine (3:1 ratio;
Abstract In this research the synthesis of 1,1′-(butane-1,4-diyl)bis(1,4-diazabicyclo[2.2.2]octan-1-ium) hydroxide as an effective basicionicliquid containing dual basic functional groups is reported. After characterization using FT-IR, 1H NMR, 13C NMR and mass analyses, this reagent is efficiently used for promotion of the synthesis of spiro-4H-pyrans via one-pot three-component condensation through a