Synthesis of cholesteryl-α-D-lactoside via generation and trapping of a stable ß-lactosyl iodide.

ABSTRACT

The generation of ß-lactosyl iodide was carried out under non-in situ-anomerization, metal free conditions by reacting commercially available ß-per-O-acetylated lactose with trimethylsilyl iodide (TMSI). The ß-iodide was surprisingly stable as evidenced by NMR spectroscopy. Introduction of octanol or cholesterol under microwave conditions gave high yields of α-linked glycoconjugates. Careful analysis of the reaction products and mechanistic considerations suggest an acid catalyzed rearrangement that provides α-linked glycosylation products with a free C2-hydroxyl. Accessibility to these compounds may further advance glycolipidomic profiling of immune modulating bacterial derived-glycans.