Synthesis of type 2 Lewis antigens via novel regioselective glycosylation of an orthogonally protected lactosamine diol derivative

Abstract

The novel and efficient synthesis of type 2 Lewis antigens is reported in this study. The rationally designed lactosamine-3, 2′-diol derivative with an orthogonal set of protecting groups is efficiently glycosylated with a benzyl protected 1-thio-l-fucoside donor in a unique regioselective manner to produce Lewis x (Le[x]) and Lewis y (Le[y]) derivatives in good yields. These derivatives can be prepared not only exclusively but also synchronously by choosing the appropriate reaction temperature and donor–acceptor molar ratio. The Le[x] derivatives are easily converted into sulfated or non-sulfated Le[x] bearing a terminal azido functionalized oligo-(ethyleneoxide) linker; the Le[y] derivative having the same linker can also be prepared, all of which can be further used for the chemical modification of other compounds and materials.