A Practical Synthesis of Sugar-Derived Cyclic Nitrones: Powerful Synthons for the Synthesis of Iminosugars

Abstract

All reagents were used as received from commercial sources without further purification or prepared as described in the literature. Reactions were stirred using Teflon-coated magnetic stirring bars. Analytical TLC was performed with 0.20 mm silica gel 60F plates with 254 nm fluorescent indicator. TLC plates were visualized by ultraviolet light or by treatment with a spray of Pancaldi reagent {(NH 4) 6 MoO 4 , Ce(SO 4) 2 , H 2 SO 4 , H 2 O}. Chromatographic purification of products was carried out by flash column chromatography on silica gel (200-300 mesh). Infrared spectra were recorded on a JASCO FT/IR-480 plus Fourier transform spectrometer. NMR spectra were measured in CDCl 3 (with TMS as internal standard) or D 2 O on a Bruker AV300 (1 H at 300 MHz, 13 C at 75 MHz) or AV600 magnetic resonance spectrometer. Chemical shifts (δ) are reported in ppm, and coupling constants (J) are in Hz. The following abbreviations were used to explain the multiplicities: s = singlet, d = doublet, t = triplet, q = quartet, m = multiplet. Rotation values were recorded on AA10-R polarimeter at the wavelength of sodium D-line (589 nm) at 20°C. Melting points were determined using a FischereJohn melting point apparatus.