ABSTRACT
The popular CuAAC (Cu(I)-catalyzed azide-alkyne 1,3-dipolar cycloaddition), also referred to as the click reaction, has been adopted by carbohydrate chemists for the construction of neoglycoconjugates. Thus, the synthesis of alkynyl- and azide-sugar precursors through readily available and high-yielding methods has become an important topic. One option for the synthesis of neoglycoconjugates is to employ thiosugars as recognition elements, which are more flexible isosteric structures than the naturally occurring O-glycosides. The phthalimido group is a useful alternative for the preparation of hexosamine building blocks, as it prevents the participation of the NH group in many side reactions. A traditional alternative method to access thioglycosides involves the preparation of anomeric halides, conversion thereof to the corresponding isothiouronium salts, followed by reaction with a base in the presence of an electrophile.
