R. R. Schmidt and co-workers have described the selective anomeric activation of O-protected hexopyranoses (glucose, galactose, mannose, glucosamine, galactosamine), hexofuranoses and pentopyranoses with trichloroacetonitrile in the presence of a base, as well as glycosylations under acid catalysis.
Under kinetic control with potassium carbonate as the base, β-trichloroacetimidates are formed selectively, whereas with sodium hydride, caesium carbonate or potassium hydroxide and in the presence of phase-transfer catalysts only α-trichloroacetimidates are obtained (thermodynamically controlled).
The trichloroacetimidates are reacted between −40 °C and room temperature with boron trifluoride etherate in dichloromethane with O-protected sugars. This method usually gives better results than the Koenigs–Knorr method using silver salts or the Helferich method which uses problematic mercury salts. Since an inversion occurs at the anomeric center, the reaction leads to β-O-glycosides (when using α-trichloroacetimidates). The trichloroacetimidate method often produces sterically uniform glycosides under mild reaction conditions in very good yields.
Thioacetic acid reacts with acetyl-protected α-galactosyl trichloroacetimidate even without additional acid catalysis to thioglycoside, from which (after cleavage of the protective groups) 1-thio-β--galactose is easily accessible, which is useful for the separation of racemates of amino acids.
Trichloroacetonitrile was an important fumigant in the first half of the 20th century, but today it has become obsolete for this application.