Synthesis of Benzohydroxamic Acid Glucosides and Galactosides
Compounds 1 and 2 were prepared according to known procedure.9 2,2,2-TriuoroN-phenylacetimidoyl chloride was prepared following the procedure by Tamura et al.8 and was found stable up to 6 months at −18°C. Benzohydroxamic acid and molecular sieves (4Å) were purchased from Aldrich. All reactions were performed under N2 atmosphere. These reactions were monitored by TLC on precoated silica gel plates (Macherey-Nagel ALUGRAM® SIL G/UV254, 0.2 mm silica gel 60 Å). Spots were visualized under 254 nm UV light and/or charring with a solution of 3 g of phosphomolybdic acid in 100 mL of ethanol. Flash column chromatography was performed using Macherey-Nagel silica gel 60 (15-40 µm). 1H and 13C NMR were performed on an Avance 300 Bruker spectrometer. Chemical shifts are expressed in part per million (ppm) relative to TMS (δ = 0 ppm) and the coupling constants J in hertz (Hz). NMR multiplicities are reported as b = broad, s = singlet, d = doublet, t = triplet, q = quadruplet, and m = multiplet. Proton and carbon signals have been assigned through DEPT 135, 1H-1H correlation, and 1H-13C correlation experiments. Stereochemistry at the anomeric position for compounds 3 and 4 were determined by NOESY experiment and proved to be β-glycosides. Optical rotation was measured on a Schmidt + Haensch polartronic HH8 polarimeter.