Helferich method

The Helferich method may refer to:

1) Glycosylation of an alcohol using a glycosyl acetate as donor and a Lewis acid (eg a metal halide) as promoter [1].

2) Glycosylation of an alcohol using a glycosyl halide as a donor and a mercury salt as promoter (cf the Koenigs Knorr reaction, which uses silver salts as promoters) [2].

[1] B. Helferich, E. Schmitz-Hillebrecht, Ber. 66, 378 (1933). [2] B. Helferich, J. Zirner, Chem. Ber. 95, 2604 (1962).