Abstract
For the synthesis of large oligosaccharides and biologically active oligosaccharide derivatives it is often desirable to use a block synthesis, that is to link an oligosaccharide residue to another or to a non-carbohydrate aglycon. It is sometimes difficult to prepare glycosyl halide derivatives of the oligosaccharides in good yields, and there is a need for glycosylating agents which can be prepared under mild conditions and in good yields.