The reaction of dimethyl squarate with aminodeoxy sugars, aminodeoxy alditols, amino aldonic acids, and glycosyl amines under neutral conditions furnished the squaric amide esters, which were converted in more alkaline media (pH approximate to 8) into the asymmetric squaric diamides. The unprotected squaric acid amide esters are suitable for constructing a specific anchor (spacer, linker) function that favorably influences the watersolubility of the resulting drugs and glycoconjugates.