General informationAll chemicals and reagents were purchased from Merck (Darmstadt, Germany) or Aldrich (Missouri, United States), and used without purification. Melting points were measured on an Electrothermal 9100 (Staffordshire, United Kingdom) apparatus. 1 H and 13 C NMR spectra were recorded on a Bruker DRX-400 AVANCE (Massachusetts, United States) spectrometer at 400.13 and 100.61 MHz, respectively. Chemical shifts are given in parts per million (δ) relative to internal tetramethylsilane standard and coupling constants (J) are reported in hertz (Hz). IR spectra were recorded on a Bruker Tensor 27 (Massachusetts, United States) spectrometer. Mass spectra were determined on a Finnigan-Matt 8430 (Waltham, United States) mass spectrometer operating at an ionization potential of 70 eV. Elemental analyses were carried on a Perkin-Elmer 2400II CHNS/O Elemental Analyzer (Massachusetts, United States).
General procedure for the synthesis of compounds (5a-5j)A mixture of aromatic aldehydes 1 (1 mmol), aniline 2 (0.1 mL, 1 mmol), rhodanine-N-acetic acid 3 (0.2 g, 1 mmol) and alkyl isocyanides