Bromodeoxy Sugars from Epoxides: Methyl 5-O-Acetyl-3-bromo-3-deoxy-α-d-arabinofuranoside, Methyl 5-O-Acetyl-2-bromo-2-deoxy-β-d-xylofuranoside, and Methyl 5-O-Acetyl-3-bromo-3-deoxy-β-d-arabinofuranoside