Materials and methods Apparatus and analysis General procedure for
Reaction courses and the resulted products were monitored by thin-layer chromatography (TLC) on the self-made pre-coated BIBR 953 gel 60 F254 plates. Spots were detected by a UV lamp visualized at 254 nm and/or 365 nm. Melting points (°C, uncorrected) were determined on a XT4 MP apparatus (Taike Corp., Beijing, China). Sonication was performed in a Kunshan KQ 500E ultrasonic cleaner (Kun Shan Ultrasonic Instruments Co., Ltd., Jiangsu, China) with a frequency of 40 kHz, an ultrasonic power of 500 W and a heating power of 800 W. The size of the reactor is 530 mm length, 320 mm width and 380 mm depth. In the reactor, the size of the water bath is 500 mm length, 300 mm width and 150 mm depth. The reaction mixture was irradiated at 20–80 °C for appropriate time. The reaction flask was positioned in the maximum energy area in the cleaner with cycled water running to control the desired temperature of the water bath. The IR spectra were recorded on a Thermo iS10 IR spectrometer (KBr pellets) and 1H NMR spectra were recorded in CDCl3 or d6-DMSO on a Bruker DPX400 spectrometer with TMS and solvent signals allotted as internal standards. Splitting patterns are as follows: s, singlet; d, doublet; dd, double doublets; t, triplet; q, quartet; m, multiplet. Chemical shifts are reported in δ (ppm) and coupling constants are given in Hertz. ESI mass spectra were recorded on the Shimadzu LCMS-IT-TOF mass spectrometer. All reagents are A.R. grade and purchased from Aladdin Industrial Corporation.