2.1 Materials and instruments

The specifications and sources of the chemicals used in this work are summarized in Table S1 . All reagents were used without further purification. NMR spectra was obtained on a Bruker DPX 400 MHz spectrometer with CDCl3 as internal standard solvent at ambient temperature. FT-IR spectra was carried out on Nicolet iS50 infrared spectrometer, with the spectral resolution and the number of scans of 4 cm-1 and 32, respectively. Conversion and selectivity of epoxides were determined by HPLC analysis. ESI-MS was used to characterize the molecular weight of the product at m/z.