Synthesis of a 1,2- cis -indoxyl galactoside as a chromogenic glycosidase substrate.

A synthetically challenging 1,2- cis -indoxyl galactoside, X-α-galactoside, was first prepared in this study using a cyclic ketone indoxyl acceptor and a glycosyl trichloroacetimidate donor to produce an enol glycoside and a 4,6- O -di- tert -butylsilylene-protected galactosyl donor to complete the synthesis. The target compound shows enzyme activity in the presence of α-galactosidase.