The reactions were carried out by magnetic stirring at about 300–800 rpm; the reaction mixtures were heated using a silicon oil bath electrically regulated within ±2°C. The infrared spectra were taken with a Perkin–Elmer 1600 Fourier-transform infrared spectroscopy (FTIR) spectrophotometer and were sent to a Perkin–Elmer data manager (PEDM) installed on an IBM-PC computer. These spectra were standardized using the blank, flat, smooth, and abex functions of the PEDM software and were evaluated according to the intensities of the changing peak, by the logarithm of the relative absorbances as well as by areas. The transmittance was set ranging from 100% to 1.5%, with a completely horizontal baseline for each spectrum. Areas of standardized spectra were only compared to each other, and other reference bands were needed only for the infrared difference spectra (IDS). The 1H and 13C nuclear magnetic resonance (NMR) spectra were recorded at a Bruker 200 MHz spectrometer and then on a Bruker 400 MHz spectrometer.